Dyslipidaemia and Lipid Management

1. Clinical Overview

Summary

Dyslipidaemia encompasses a spectrum of lipid abnormalities characterized by elevated low-density lipoprotein cholesterol (LDL-C), reduced high-density lipoprotein cholesterol (HDL-C), elevated triglycerides, or combinations thereof. [1] It represents the single most important modifiable risk factor for atherosclerotic cardiovascular disease (ASCVD), which remains the leading cause of mortality worldwide. [2]

The pathophysiology centers on LDL-C as the primary atherogenic lipoprotein, with accumulation in the arterial intima initiating the atherosclerotic cascade. [3] Primary dyslipidaemia results from genetic disorders such as familial hypercholesterolaemia (FH), familial combined hyperlipidaemia (FCH), and familial hypertriglyceridaemia, while secondary causes include metabolic disorders (diabetes mellitus, metabolic syndrome), endocrine diseases (hypothyroidism, Cushing's syndrome), renal disease (nephrotic syndrome, chronic kidney disease), cholestatic liver disease, and medications (thiazide diuretics, beta-blockers, glucocorticoids, immunosuppressants). [4]

Management strategies are stratified by cardiovascular risk. In primary prevention, the QRISK3 calculator estimates 10-year ASCVD risk, with statin therapy recommended for individuals with ≥10% risk. [5] In secondary prevention (established ASCVD), high-intensity statin therapy forms the cornerstone of treatment. [6] Add-on therapies including ezetimibe, PCSK9 inhibitors (evolocumab, alirocumab), bempedoic acid, and inclisiran provide additional LDL-C lowering when targets are not achieved. [7,8]

Familial hypercholesterolaemia, affecting approximately 1 in 250 individuals, represents a critical diagnosis requiring early detection and aggressive treatment. [9] Cascade screening of first-degree relatives identifies additional affected individuals, preventing premature cardiovascular events.

Severe hypertriglyceridaemia (> 10 mmol/L) constitutes a medical emergency due to acute pancreatitis risk, requiring urgent intervention with fibrates, omega-3 fatty acids, dietary fat restriction, and management of precipitating factors. [10]

Key Facts

• LDL-Cholesterol: Primary atherogenic lipoprotein - each 1 mmol/L reduction reduces major cardiovascular events by approximately 22% [11]
• HDL-Cholesterol: Facilitates reverse cholesterol transport; low levels (less than 1.0 mmol/L men, less than 1.2 mmol/L women) increase cardiovascular risk [1]
• Triglycerides: > 10 mmol/L significantly increases acute pancreatitis risk; 5-10 mmol/L moderately increases risk [10]
• Familial Hypercholesterolaemia (FH): Prevalence ~1 in 250; untreated men have 50% risk of coronary heart disease by age 50 [9]
• Statin Therapy: Reduces major vascular events by 20-25% per mmol/L LDL-C reduction [11]
• QRISK3: Preferred cardiovascular risk assessment tool in UK primary prevention; incorporates ethnicity, deprivation, chronic diseases [5]
• PCSK9 Inhibitors: Reduce LDL-C by 50-60% when added to statin therapy; reduce cardiovascular events by ~15% over 2-3 years [7]
• Lipoprotein(a): Independent cardiovascular risk factor; elevated levels (> 50 mg/dL) increase risk; measure once for risk stratification [12]

Clinical Pearls

"LDL is the Culprit": Mendelian randomization studies and lifelong exposure data confirm LDL-C as causally related to atherosclerotic cardiovascular disease. Lower is better, with no lower safety threshold identified. [3]

"Suspect FH if TC > 7.5 mmol/L": Total cholesterol > 7.5 mmol/L (or LDL-C > 4.9 mmol/L) in the absence of secondary causes should trigger FH screening using Simon Broome or Dutch Lipid Clinic criteria. Family history of premature CVD (less than 60 years first-degree relative, less than 50 years second-degree relative) supports diagnosis. [9]

"Triglycerides > 10 = Pancreatitis Emergency": Severe hypertriglyceridaemia (> 10 mmol/L) causes up to 10% of acute pancreatitis cases. Admit for fasting, IV fluids, insulin infusion if needed, and initiate fibrate therapy. [10]

"Statins Save Lives": Meta-analysis of 170,000 participants demonstrates statins reduce all-cause mortality, cardiovascular mortality, myocardial infarction, and stroke. Number needed to treat for 5 years to prevent one major vascular event ranges from 20 (secondary prevention) to 100 (low-risk primary prevention). [11]

"Ezetimibe is Evidence-Based Add-On": The IMPROVE-IT trial demonstrated that adding ezetimibe to statin therapy reduces cardiovascular events by absolute 2% over 7 years in post-ACS patients. [13]

"PCSK9 Inhibitors for High-Risk/FH": FOURIER and ODYSSEY OUTCOMES trials established PCSK9 inhibitor efficacy in reducing cardiovascular events when added to maximally tolerated statin therapy in very high-risk patients. [7,8]

"Check for Secondary Causes First": Before diagnosing primary dyslipidaemia, exclude hypothyroidism (TSH), diabetes (HbA1c), nephrotic syndrome (urinalysis), chronic kidney disease (eGFR), cholestasis (LFTs), and review medications. [4]

"Non-HDL-C Captures All Atherogenic Lipoproteins": Non-HDL-C (total cholesterol minus HDL-C) includes LDL, VLDL, IDL, and lipoprotein(a). Superior to LDL-C alone in predicting cardiovascular risk, especially with elevated triglycerides. [1]

"Statin Myopathy is Overdiagnosed": True statin-associated rhabdomyolysis is rare (1 in 10,000). Muscle symptoms (SAMS) occur in 5-10% but often persist after statin cessation, suggesting nocebo effect. Consider rechallenge, alternate statins, or alternate-day dosing. [14]

"Measure Lp(a) Once for Risk Stratification": Lipoprotein(a) levels are genetically determined and stable over time. Measure once to identify patients with elevated levels (> 50 mg/dL or > 125 nmol/L) who warrant more aggressive LDL-C lowering. [12]

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2. Epidemiology

Prevalence

Global Burden

• Elevated LDL-C (> 3.0 mmol/L) affects approximately 50% of adults in developed countries [1]
• Dyslipidaemia contributes to 4.4 million deaths annually worldwide from ischaemic heart disease and stroke [2]
• Low- and middle-income countries demonstrate increasing prevalence paralleling economic development and dietary westernization [2]

Age and Sex Distribution

• LDL-C levels increase with age, particularly in women post-menopause [1]
• Men develop elevated LDL-C earlier (typically 4th-5th decade) compared to women (5th-6th decade) [1]
• HDL-C levels typically higher in women (protective effect from oestrogen) [1]

Familial Hypercholesterolaemia (FH)

• Heterozygous FH: 1 in 250 individuals (previously estimated 1 in 500) [9]
• Homozygous FH: 1 in 160,000-300,000 individuals [9]
• Underdiagnosed: less than 10% of FH patients identified in most countries [9]
• Cascade screening identifies additional cases in 40-50% of first-degree relatives [9]

Familial Combined Hyperlipidaemia (FCH)

• Prevalence: 1-2% of general population [15]
• Most common inherited dyslipidaemia [15]
• Accounts for 10-20% of premature coronary artery disease [15]

Hypertriglyceridaemia

• Moderate hypertriglyceridaemia (2-5 mmol/L): 15-20% of adults [10]
• Severe hypertriglyceridaemia (> 10 mmol/L): 1-2% of population [10]
• Male predominance (2-3:1 ratio) [10]

Risk Factors

Non-Modifiable Risk Factors

• Genetics: FH (LDLR, APOB, PCSK9 mutations); FCH (polygenic); familial hypertriglyceridaemia (LPL, APOC2 deficiency) [9,15]
• Age: Lipid levels increase with age [1]
• Sex: Male sex associated with earlier onset elevated LDL-C and lower HDL-C [1]
• Ethnicity: South Asian populations have higher triglycerides, lower HDL-C, and increased small dense LDL particles despite similar total cholesterol [1]

Modifiable Risk Factors

• Diet: High saturated fat intake (> 10% total energy) increases LDL-C by 0.5-1.0 mmol/L [16]
• Physical Inactivity: Sedentary lifestyle associated with 5-10% lower HDL-C [16]
• Obesity: Each 10 kg weight gain increases LDL-C by 0.2 mmol/L and reduces HDL-C by 0.05 mmol/L [16]
• Smoking: Reduces HDL-C by 10-15% and increases triglycerides [16]
• Alcohol: Moderate consumption increases HDL-C; excessive consumption (> 30g/day) increases triglycerides [16]

Secondary Causes

Endocrine Disorders

• Hypothyroidism: Reduced LDL receptor expression → elevated LDL-C and triglycerides [4]
• Diabetes Mellitus: Insulin resistance → increased VLDL production, reduced lipoprotein lipase activity → elevated triglycerides, low HDL-C, small dense LDL [4]
• Cushing's Syndrome: Hypercortisolism → increased VLDL production [4]
• Growth Hormone Deficiency: Reduced LDL receptor expression → elevated LDL-C [4]
• Polycystic Ovary Syndrome: Insulin resistance → dyslipidaemia pattern similar to metabolic syndrome [4]

Renal Disorders

• Nephrotic Syndrome: Hypoalbuminaemia → increased hepatic lipoprotein synthesis → severe hypercholesterolaemia (often > 10 mmol/L) [4]
• Chronic Kidney Disease: Multiple mechanisms including reduced lipoprotein lipase, uraemic toxins → elevated triglycerides, low HDL-C [4]

Hepatic Disorders

• Cholestasis: Impaired bile acid excretion → accumulation of lipoprotein X → elevated cholesterol [4]
• Primary Biliary Cholangitis: Can present with cholesterol > 15 mmol/L [4]

Medications

• Thiazide Diuretics: Increase LDL-C by 5-10%, triglycerides by 10-20% [4]
• Beta-Blockers (non-selective): Reduce HDL-C by 10-15%, increase triglycerides [4]
• Glucocorticoids: Dose-dependent increase in LDL-C and triglycerides [4]
• Immunosuppressants (Ciclosporin, Tacrolimus): Increase LDL-C and triglycerides [4]
• Protease Inhibitors (HIV treatment): Significant hypertriglyceridaemia, increased LDL-C [4]
• Oestrogen (oral): Increases triglycerides, may precipitate pancreatitis in susceptible individuals [4]
• Isotretinoin: Dose-dependent hypertriglyceridaemia [4]
• Antipsychotics (especially Olanzapine, Clozapine): Metabolic syndrome, dyslipidaemia [4]

Other Conditions

• Pregnancy: Physiological increase in triglycerides (2-3 fold) and cholesterol; severe hypertriglyceridaemia may cause pancreatitis in third trimester [4]
• Anorexia Nervosa: Paradoxical hypercholesterolaemia despite malnutrition [4]
• Systemic Lupus Erythematosus: Accelerated atherosclerosis, dyslipidaemia [4]

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3. Pathophysiology

Lipoprotein Metabolism

Lipoprotein Structure and Classification

Lipoproteins are spherical particles consisting of:

• Core: Hydrophobic triglycerides and cholesteryl esters
• Surface: Phospholipid monolayer, free cholesterol, apolipoproteins (provide structural integrity and receptor recognition)

Exogenous (Dietary) Lipid Pathway

1. Intestinal Absorption: Dietary fats absorbed as fatty acids and cholesterol in small intestine
2. Chylomicron Formation: Enterocytes package triglycerides and cholesterol into chylomicrons with apoB-48
3. Lymphatic Transport: Chylomicrons enter lymphatics → thoracic duct → systemic circulation
4. Lipoprotein Lipase Action: In capillary endothelium (muscle, adipose), lipoprotein lipase (LPL) activated by apoC-II hydrolyzes triglycerides → free fatty acids absorbed by tissues
5. Remnant Formation: Chylomicron remnants enriched in cholesteryl esters
6. Hepatic Uptake: Remnants bind hepatic LDL receptors and LRP via apoE → endocytosis

Endogenous (Hepatic) Lipid Pathway

1. VLDL Synthesis: Hepatocytes synthesize VLDL particles containing endogenous triglycerides and cholesterol with apoB-100
2. VLDL Secretion: Secreted into circulation
3. Lipolysis: LPL hydrolyzes VLDL triglycerides → IDL (intermediate density lipoprotein)
4. IDL Fate:
   • 50% taken up by liver via LDL receptor (apoE recognition)
   • 50% converted to LDL by hepatic lipase
5. LDL Formation: LDL particles rich in cholesterol with apoB-100
6. LDL Clearance:
   • 70% via hepatic LDL receptors (apoB-100 recognition)
   • 30% via peripheral tissue LDL receptors
   • Scavenger pathway (oxidized LDL → macrophages)

Reverse Cholesterol Transport (HDL Pathway)

1. HDL Formation: Nascent HDL (discoid particles) secreted by liver and intestine with apoA-I
2. Cholesterol Efflux: ABCA1 transporter on peripheral cells transfers free cholesterol to apoA-I
3. Cholesterol Esterification: LCAT (lecithin-cholesterol acyltransferase) activated by apoA-I converts free cholesterol to cholesteryl esters → spherical HDL particles
4. HDL Maturation: Additional cholesterol acquired via ABCG1 and SR-BI; particles enlarge (HDL3 → HDL2)
5. Cholesteryl Ester Transfer: CETP transfers cholesteryl esters from HDL to VLDL/LDL in exchange for triglycerides
6. Hepatic Uptake:
   • Direct: SR-BI (scavenger receptor class B type I) selectively takes up cholesteryl esters
   • Indirect: HDL-derived cholesteryl esters transferred to VLDL/LDL → hepatic LDL receptor uptake

Atherosclerosis Pathogenesis

LDL and Atherogenesis [3]

1. Endothelial Dysfunction: Risk factors (hypertension, smoking, diabetes, oxidative stress) → endothelial permeability
2. LDL Retention: LDL particles cross endothelium → bind proteoglycans in subendothelial space (intima)
3. LDL Modification: Oxidation, glycation, lipolysis → modified LDL (oxLDL)
4. Inflammatory Response:
   • Endothelial cells express adhesion molecules (VCAM-1, ICAM-1, selectins)
   • Monocyte recruitment and adhesion
   • Monocyte migration into intima via MCP-1 gradient
   • Differentiation to macrophages
5. Foam Cell Formation:
   • Macrophages express scavenger receptors (CD36, SR-A, LOX-1)
   • Unregulated uptake of oxLDL (unlike LDL receptor, no negative feedback)
   • Cholesteryl ester accumulation → foam cells
6. Fatty Streak: Earliest visible lesion; foam cells accumulate in intima
7. Plaque Progression:
   • Smooth muscle cell migration from media to intima
   • SMC proliferation stimulated by growth factors (PDGF, FGF)
   • Extracellular matrix synthesis (collagen, elastin, proteoglycans)
   • Fibrous cap formation overlying lipid core
   • Necrotic core formation (foam cell apoptosis/necrosis)
8. Advanced Plaque:
   • Calcification (osteoblast-like differentiation)
   • Neovascularization (intraplaque hemorrhage risk)
   • Thinning of fibrous cap (matrix metalloproteinases)
9. Plaque Rupture:
   • Thin-cap fibroatheroma vulnerable to rupture
   • Exposure of thrombogenic lipid core
   • Platelet adhesion and aggregation
   • Thrombus formation → acute coronary syndrome, stroke

Role of HDL in Atheroprotection [1]

• Reverse Cholesterol Transport: Removes cholesterol from peripheral tissues and arterial wall macrophages
• Antioxidant: Paraoxonase-1 (PON1) on HDL prevents LDL oxidation
• Anti-inflammatory: Inhibits endothelial adhesion molecule expression
• Endothelial Protection: Promotes nitric oxide production, inhibits apoptosis
• Antithrombotic: Inhibits platelet aggregation

Genetic Dyslipidaemias

Familial Hypercholesterolaemia (FH) [9]

Genetics:

• Autosomal Dominant inheritance
• Heterozygous FH: One mutant allele; prevalence ~1 in 250
• Homozygous FH: Two mutant alleles; prevalence ~1 in 160,000-300,000; severe phenotype

Gene Mutations (decreasing frequency):

1. LDLR (Low-Density Lipoprotein Receptor): 85-90% of cases

   • 2000 different mutations identified

   • Loss of function → reduced LDL-C clearance
   • Null mutations (no receptor) vs defective mutations (reduced function)
2. APOB (Apolipoprotein B-100): 5-10% of cases
   • Mutation in LDL receptor-binding domain of apoB-100
   • "Familial Defective ApoB-100" (FDB)
   • R3500Q most common mutation
3. PCSK9 (Proprotein Convertase Subtilisin/Kexin Type 9): 1-3% of cases
   • Gain-of-function mutations
   • PCSK9 promotes LDL receptor degradation
   • Increased PCSK9 activity → fewer LDL receptors → elevated LDL-C
4. LDLRAP1 (LDL Receptor Adaptor Protein 1): Rare
   • Autosomal recessive inheritance
   • Impaired LDL receptor internalization

Pathophysiology:

• Reduced hepatic LDL receptor number/function
• Impaired LDL-C clearance from circulation
• LDL-C elevated from birth
• Lifelong exposure to elevated LDL-C → accelerated atherosclerosis
• Heterozygous FH: LDL-C typically 5-10 mmol/L (2-3x normal)
• Homozygous FH: LDL-C typically > 13 mmol/L (4-6x normal); untreated, MI in childhood/adolescence

Familial Combined Hyperlipidaemia (FCH) [15]

Genetics:

• Polygenic disorder (no single gene identified)
• Familial clustering but complex inheritance
• Prevalence 1-2% of general population

Phenotype:

• Variable lipid profile within family and over time in individual:
  • "Type IIa: Elevated LDL-C only"
  • "Type IIb: Elevated LDL-C + triglycerides"
  • "Type IV: Elevated triglycerides only"
• Small dense LDL particles (pattern B)
• Elevated apoB-100 disproportionate to LDL-C
• Low HDL-C
• Often associated with metabolic syndrome features

Pathophysiology:

• Hepatic overproduction of apoB-100 and VLDL
• Increased VLDL secretion → elevated triglycerides
• VLDL conversion to LDL → elevated LDL-C
• Insulin resistance frequently present

Familial Hypertriglyceridaemia

Lipoprotein Lipase Deficiency (Type I Hyperlipoproteinaemia):

• Autosomal recessive
• Absent/severely reduced LPL activity
• Inability to hydrolyze chylomicron and VLDL triglycerides
• Severe hypertriglyceridaemia (> 20 mmol/L)
• Eruptive xanthomas, lipaemia retinalis, hepatosplenomegaly
• Recurrent pancreatitis from childhood

ApoC-II Deficiency:

• Autosomal recessive
• ApoC-II is LPL cofactor
• Phenotype similar to LPL deficiency

Lipoprotein(a) [12]

Structure:

• LDL-like particle with additional apolipoprotein(a) covalently bound to apoB-100
• Apo(a) structurally similar to plasminogen (multiple kringle domains)

Genetics:

• LPA gene on chromosome 6
• Highly polymorphic (size isoforms)
• Lp(a) levels 70-90% genetically determined
• Stable throughout adult life

Pathophysiology:

• Atherogenic: Cholesterol delivery to arterial wall
• Thrombogenic: Apo(a) inhibits fibrinolysis (plasminogen homology)
• Pro-inflammatory: Carries oxidized phospholipids

Clinical Significance:

• Elevated Lp(a) (> 50 mg/dL or > 125 nmol/L) independent cardiovascular risk factor
• Particularly important in FH (synergistic risk)
• No established pharmacological intervention (statins ineffective; PCSK9 inhibitors reduce Lp(a) 20-30% but unclear if this drives benefit)

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4. Clinical Presentation

Asymptomatic Detection

Majority of Dyslipidaemia Cases

• Dyslipidaemia itself asymptomatic
• Detected on screening lipid profile:
  • "NHS Health Check (England): Ages 40-74 every 5 years"
  • Opportunistic screening in primary care
  • Pre-insurance/employment medicals
• First presentation may be acute cardiovascular event (MI, stroke) or chronic ASCVD (angina, claudication)

Clinical Signs of Severe Dyslipidaemia

Xanthomas (cholesterol deposition in tissues)

Corneal Arcus (arcus senilis, arcus corneae)

• White or grey ring at corneal periphery
• Cholesterol deposition in corneal stroma
• Age less than 45 years: Suspicious for FH or severe hypercholesterolaemia (arcus "juvenilis")
• Age > 45 years: Common, less specific (present in 60% by age 60)
• Not pathognomonic but should prompt lipid assessment in young patients

Lipaemia Retinalis

• Pale, creamy appearance of retinal vessels
• Occurs when triglycerides > 20-25 mmol/L
• Suggests severe hypertriglyceridaemia (often genetic)
• Pancreatitis risk very high

Other Physical Signs

• Hepatosplenomegaly: Severe hypertriglyceridaemia (foam cell accumulation)
• Signs of Cardiovascular Disease:
  • Absent pulses (peripheral arterial disease)
  • Carotid bruits (carotid stenosis)
  • Arcus senilis in context of CAD suggests dyslipidaemia
  • Premature male pattern baldness, diagonal earlobe crease (CVD associations, not lipid-specific)

Familial Hypercholesterolaemia Clinical Criteria

Simon Broome Criteria (UK)

Definite FH (one of):

1. Total cholesterol > 7.5 mmol/L or LDL-C > 4.9 mmol/L (adults) PLUS Tendon xanthomas (patient or 1st/2nd degree relative)

Possible FH (one of):

1. Total cholesterol > 7.5 mmol/L or LDL-C > 4.9 mmol/L (adults) PLUS Family history of MI less than 60 years (1st degree) or less than 50 years (2nd degree relative) OR Family history of elevated total cholesterol > 7.5 mmol/L (1st/2nd degree relative)

2. Total cholesterol > 6.7 mmol/L or LDL-C > 4.0 mmol/L (children less than 16 years) PLUS Family history as above

Dutch Lipid Clinic Network (DLCN) Criteria (scoring system)

Points assigned for:

• Family history:
  • 1st degree relative with premature CAD or vascular disease: 1 point
  • 1st degree relative with tendon xanthomas/arcus: 2 points
• Personal history:
  • "Premature CAD (less than 55 men, less than 60 women): 2 points"
  • "Premature cerebral/peripheral vascular disease: 1 point"
• Physical examination:
  • "Tendon xanthomas: 6 points"
  • "Arcus corneae less than 45 years: 4 points"
• LDL-C levels (untreated):
  • ≥8.5 mmol/L: 8 points
  • 6.5-8.4 mmol/L: 5 points
  • 5.0-6.4 mmol/L: 3 points
  • 4.0-4.9 mmol/L: 1 point
• Genetic testing:
  • "Mutation in LDLR, APOB, or PCSK9: 8 points"

Score Interpretation:

• 8 points: Definite FH

• 6-8 points: Probable FH
• 3-5 points: Possible FH
• less than 3 points: Unlikely FH

Complications as Presenting Feature

Acute Cardiovascular Events

• Acute Coronary Syndrome: Myocardial infarction (STEMI, NSTEMI), unstable angina
  • "FH patients: Men average age 48, women 57 for first MI (10-20 years earlier than general population) [9]"
  • LDL-C > 5 mmol/L at time of ACS should raise suspicion for FH
• Ischaemic Stroke: Large artery atherosclerosis, particularly carotid stenosis
• Acute Limb Ischaemia: Thromboembolism or in-situ thrombosis in PAD

Chronic Atherosclerotic Disease

• Stable Angina: Exertional chest discomfort
• Peripheral Arterial Disease: Intermittent claudication, critical limb ischaemia
• Carotid Artery Stenosis: Asymptomatic or TIA/amaurosis fugax
• Aortic Stenosis: Accelerated calcific aortic stenosis associated with elevated Lp(a) [12]

Acute Pancreatitis

• Severe hypertriglyceridaemia (> 10 mmol/L) causes ~10% of acute pancreatitis [10]
• Presentation: Severe epigastric pain radiating to back, vomiting
• "Milky" appearance of blood sample (lipaemic serum)
• Triglycerides > 5 mmol/L may interfere with laboratory assays (pseudohyponatraemia)

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5. Clinical Examination

General Inspection

• Body Habitus: Obesity (particularly central/visceral adiposity) suggests metabolic syndrome-associated dyslipidaemia
• Xanthelasma: Yellow plaques on eyelids (particularly medial canthus)
• Corneal Arcus: White/grey peripheral corneal ring (significance if less than 45 years)

Hands

• Tendon Xanthomas: Palpate extensor tendons of hands
  • Metacarpophalangeal joints
  • Proximal interphalangeal joints
  • Firm nodules within tendons
• Palmar Xanthomas: Yellow-orange discoloration of palmar creases (Type III dysbetalipoproteinaemia)

Elbows and Knees

• Tuberous Xanthomas: Yellow-orange nodules on extensor surfaces
• Eruptive Xanthomas: Small yellow papules with erythematous base (severe hypertriglyceridaemia)

Lower Limbs

• Achilles Tendon: Most important sign in FH screening
  • Inspect from lateral view (patient standing, knees slightly bent)
  • Palpate for thickening or nodules
  • Normal Achilles thickness less than 2 cm at narrowest point
  • Bilateral involvement common
• Peripheral Pulses: Assess for peripheral arterial disease
  • Femoral, popliteal, dorsalis pedis, posterior tibial
  • Absent pulses or bruits suggest atherosclerotic disease

Cardiovascular Examination

• Carotid Arteries: Auscultate for bruits (carotid stenosis)
• Praecordium:
  • Scars (previous CABG, valve surgery)
  • Apex beat displacement (LV dysfunction post-MI)
  • Murmurs (aortic stenosis associated with elevated Lp(a))

Abdomen

• Hepatosplenomegaly: Severe hypertriglyceridaemia (foam cell accumulation in reticuloendothelial system)
• Abdominal Aortic Aneurysm: Pulsatile mass (atherosclerotic disease)

Fundoscopy

• Lipaemia Retinalis: Pale, creamy retinal vessels (triglycerides > 20-25 mmol/L)
• Hypertensive/Diabetic Retinopathy: Associated cardiovascular risk factors

Other

• Thyroid Examination: Hypothyroidism as secondary cause (goitre, bradycardia, delayed relaxation of reflexes)
• Signs of Cushing's Syndrome: Central obesity, striae, proximal myopathy (secondary dyslipidaemia)

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6. Investigations

Lipid Profile

Sample Collection

• Fasting No Longer Routinely Required for lipid assessment (NICE 2023) [5]
  • Non-fasting samples adequate for total cholesterol, HDL-C, non-HDL-C
  • Fasting sample (12 hours) preferred if triglycerides > 4.5 mmol/L or assessing for diabetes
  • Random elevated triglycerides should be confirmed with fasting sample
• Avoid sampling during acute illness (lipid levels transiently reduced for 6-8 weeks post-MI, surgery, infection)
• Discontinue lipid-lowering therapy for 6 weeks if measuring baseline lipids (if clinically appropriate)

Standard Lipid Panel

Calculated Values:

• Non-HDL-C = Total Cholesterol - HDL-C
  • Captures all atherogenic lipoproteins (LDL, VLDL, IDL, Lp(a))
  • More accurate than LDL-C when triglycerides elevated
  • Primary target in many guidelines (ESC/EAS)
• LDL-C (calculated by Friedewald equation if triglycerides less than 4.5 mmol/L):
  • LDL-C = Total Cholesterol - HDL-C - (Triglycerides / 2.2)
  • Inaccurate if triglycerides > 4.5 mmol/L (direct LDL-C measurement or non-HDL-C used instead)

Additional Lipid Testing

Cardiovascular Risk Assessment

QRISK3 (UK Primary Prevention) [5]

• Estimates 10-year risk of cardiovascular disease (MI, stroke)
• Indicated: Primary prevention (no established ASCVD), age 25-84 years
• Variables:
  • Age, sex, ethnicity, smoking status
  • Blood pressure, total cholesterol, HDL-C
  • Diabetes (type 1 or 2), chronic kidney disease (stage 3-5)
  • Atrial fibrillation, rheumatoid arthritis, systemic lupus erythematosus
  • Antihypertensive treatment
  • Severe mental illness, corticosteroid use, erectile dysfunction
  • Family history of premature CHD (less than 60 years 1st degree relative)
  • Deprivation (Townsend score)
• Interpretation:
  • ≥10%: Offer statin therapy (shared decision-making)
  • less than 10%: Lifestyle modification; consider statin if additional risk factors

Framingham Risk Score (alternative in non-UK settings) ASSIGN Score (Scotland - includes deprivation) SCORE2 (European Society of Cardiology 2021)

Screening for Secondary Causes

Essential Baseline Investigations [4]

Additional Investigations (if clinically indicated):

• Fasting Insulin / HOMA-IR: Insulin resistance (metabolic syndrome, PCOS)
• 24-hour Urinary Free Cortisol / Overnight Dexamethasone Suppression Test: Cushing's syndrome
• Serum Protein Electrophoresis: Paraproteinaemia (multiple myeloma)
• Coeliac Serology: Coeliac disease (rarely causes dyslipidaemia)

Assessing Cardiovascular Complications

ECG

• Prior myocardial infarction (Q waves, T wave inversion)
• Left ventricular hypertrophy (hypertension, aortic stenosis)
• Atrial fibrillation

Echocardiography

• LV systolic dysfunction (prior MI)
• Aortic stenosis (associated with elevated Lp(a))
• Valvular disease

Carotid Doppler Ultrasound

• Carotid artery stenosis (if symptomatic or risk stratification)
• Carotid intima-media thickness (research tool)

Ankle-Brachial Pressure Index (ABPI)

• Screen for peripheral arterial disease
• less than 0.9 indicates significant PAD

Coronary Artery Calcium Scoring (CT Calcium Score)

• Risk stratification in intermediate-risk patients (QRISK 10-20%)
• Score > 400 Agatston units indicates high risk

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7. Management

Treatment Approach Overview

Principles

1. Lifestyle Modification: Foundation for all patients
2. Risk Stratification: QRISK3 (primary prevention) vs established ASCVD (secondary prevention)
3. Lipid-Lowering Therapy: Statin-based treatment as first-line
4. Treat Secondary Causes: Correct hypothyroidism, optimize diabetes control, etc.
5. Target-Driven Therapy: Aim for LDL-C or non-HDL-C targets based on risk
6. Familial Hypercholesterolaemia: Aggressive early intervention, cascade screening

Lifestyle Modification [16]

Dietary Interventions

• Reduce Saturated Fat: less than 7% total energy intake (ideally less than 10%)
  • Replace with monounsaturated (olive oil, nuts) and polyunsaturated fats (omega-3 fatty acids)
  • Reduces LDL-C by 5-10%
• Increase Dietary Fiber: 25-30 g/day (particularly soluble fiber)
  • Oats, barley, psyllium, beans, lentils, fruits
  • Reduces LDL-C by 5-15%
• Plant Sterols/Stanols: 2 g/day (fortified foods, supplements)
  • Competitively inhibit cholesterol absorption
  • Reduces LDL-C by 5-10%
• Omega-3 Fatty Acids: 2-4 g/day (oily fish, supplements)
  • Reduces triglycerides by 20-40%
  • Minimal effect on LDL-C or HDL-C
• Reduce Simple Carbohydrates: Particularly if elevated triglycerides
  • Limit sugar-sweetened beverages, refined grains
• Mediterranean Diet: Evidence for cardiovascular benefit
  • High in fruits, vegetables, whole grains, legumes, nuts, olive oil
  • Moderate fish and poultry; low red meat

Physical Activity

• Aerobic Exercise: ≥150 minutes/week moderate-intensity or ≥75 minutes/week vigorous-intensity
  • Increases HDL-C by 5-10%
  • Modest reduction in LDL-C and triglycerides
• Resistance Training: 2 sessions/week

Weight Management

• Weight Loss: If overweight/obese (BMI ≥25 kg/m²)
  • Each 10 kg weight loss → LDL-C ↓ 0.2 mmol/L, TG ↓ 0.3 mmol/L, HDL-C ↑ 0.05 mmol/L

Smoking Cessation

• Improves HDL-C by 10-15%
• Reduces cardiovascular events independent of lipid effects
• Refer to smoking cessation services

Alcohol Moderation

• Moderate Consumption (≤14 units/week): May increase HDL-C
• Excessive Consumption (> 30 g/day): Increases triglycerides significantly
• Abstinence if severe hypertriglyceridaemia

Pharmacological Therapy: Statins

Mechanism of Action [11]

• HMG-CoA Reductase Inhibition: Rate-limiting enzyme in hepatic cholesterol synthesis
• Reduced intracellular cholesterol → upregulation of LDL receptors → increased LDL-C clearance
• LDL-C reduction: 30-55% (dose and statin-dependent)

Statin Intensity Classification

Indications and Dosing (NICE Guidelines) [5,6]

Primary Prevention:

• QRISK3 ≥10%: Offer Atorvastatin 20 mg once daily
• Type 1 Diabetes: Atorvastatin 20 mg if age > 40, duration > 10 years, nephropathy, or other CVD risk factors
• Chronic Kidney Disease (eGFR less than 60): Atorvastatin 20 mg

Secondary Prevention:

• Established ASCVD (prior MI, ACS, stroke, TIA, PAD): Atorvastatin 80 mg once daily
• Type 2 Diabetes + QRISK ≥10%: Atorvastatin 20 mg (consider 80 mg if high risk)

Familial Hypercholesterolaemia:

• Start in childhood (age > 10 years; consider age 8-10 if homozygous FH or severe phenotype)
• Adults: Atorvastatin 80 mg or Rosuvastatin 40 mg
• Children: Atorvastatin 10-20 mg (titrate)
• Target: ≥50% LDL-C reduction from baseline

Monitoring [6]

• Baseline: Lipid profile, LFTs, CK (if symptoms)
• 3 Months: Repeat lipid profile, LFTs
  • "Target: ≥40% reduction in non-HDL-C (NICE)"
  • "Target: LDL-C less than 1.8 mmol/L (ESC/EAS for very high risk)"
• Annual Review: Lipids, LFTs, adherence, symptoms
• LFT Monitoring:
  • Stop statin if ALT > 3× ULN
  • Consider continuing if ALT 1-3× ULN (often transient)

Adverse Effects [14]

Drug Interactions:

• CYP3A4 Inhibitors increase statin levels (Atorvastatin, Simvastatin, Lovastatin):
  • Macrolides (Clarithromycin, Erythromycin), Azole Antifungals (Itraconazole, Ketoconazole)
  • Protease Inhibitors, Ciclosporin, Verapamil, Diltiazem, Grapefruit Juice
  • "Contraindicated with Simvastatin: Gemfibrozil (use Fenofibrate if fibrate needed)"
• Rosuvastatin, Pravastatin, Fluvastatin: Minimal CYP metabolism (fewer interactions)

Pharmacological Therapy: Add-On Agents

Ezetimibe [13]

• Mechanism: Inhibits Niemann-Pick C1-Like 1 (NPC1L1) protein in intestinal brush border → blocks cholesterol absorption
• LDL-C Reduction: 15-20%
• Dose: 10 mg once daily (can combine with any statin)
• Indications:
  • LDL-C target not achieved with maximally tolerated statin
  • Statin intolerance (use as monotherapy)
  • Familial hypercholesterolaemia
• Evidence: IMPROVE-IT trial (post-ACS patients): Simvastatin + Ezetimibe vs Simvastatin alone
  • "LDL-C: 1.4 mmol/L vs 1.8 mmol/L"
  • 2% absolute reduction in cardiovascular events over 7 years (NNT 50)
• Adverse Effects: Generally well-tolerated; diarrhoea (rare)

PCSK9 Inhibitors [7,8]

• Mechanism: Monoclonal antibodies bind PCSK9 → prevent PCSK9-mediated degradation of LDL receptors → increased LDL-C clearance
• Agents:
  • "Evolocumab (Repatha): 140 mg SC every 2 weeks or 420 mg SC monthly"
  • "Alirocumab (Praluent): 75-150 mg SC every 2 weeks"
• LDL-C Reduction: 50-60%
• Indications (NICE TA394, TA393):
  • "Primary hypercholesterolaemia/mixed dyslipidaemia:"
    • Secondary Prevention: LDL-C ≥4.0 mmol/L despite maximally tolerated statin + ezetimibe
    • Primary Prevention (high-risk): LDL-C ≥5.0 mmol/L despite maximally tolerated statin + ezetimibe
  • "Heterozygous FH: LDL-C ≥4.0 mmol/L despite maximally tolerated lipid-lowering therapy"
  • "Homozygous FH: Add-on to other therapies"
• Evidence:
  • "FOURIER Trial (Evolocumab + Statin vs Statin): 1.5% absolute reduction in cardiovascular events over 2.2 years (NNT 67)"
  • "ODYSSEY OUTCOMES Trial (Alirocumab + Statin post-ACS): 1.6% absolute reduction in cardiovascular events over 2.8 years (NNT 63)"
• Adverse Effects: Injection site reactions, flu-like symptoms (uncommon), nasopharyngitis
• Cost: ~£4,000-5,000/year (restricts use to very high-risk patients)

Bempedoic Acid [14]

• Mechanism: Prodrug activated in liver; inhibits ATP citrate lyase (upstream of HMG-CoA reductase) → reduces cholesterol synthesis
  • Not activated in muscle (no myopathy)
• LDL-C Reduction: 15-25%
• Dose: 180 mg once daily
• Indications:
  • Statin intolerance (myopathy)
  • Inadequate LDL-C reduction despite statin + ezetimibe
• Evidence: CLEAR Outcomes trial (2023): Reduced cardiovascular events in statin-intolerant patients
• Adverse Effects: Elevated uric acid (gout risk), tendon rupture (rare)

Inclisiran

• Mechanism: Small interfering RNA (siRNA) targeting PCSK9 mRNA → reduces PCSK9 synthesis
• LDL-C Reduction: 50%
• Dose: 284 mg SC at baseline, 3 months, then every 6 months
• Advantage: Twice-yearly dosing (vs every 2 weeks for PCSK9 monoclonal antibodies)
• Indications: Similar to PCSK9 inhibitors (high-risk patients, FH)
• Evidence: ORION trials demonstrated LDL-C reduction; cardiovascular outcomes trial ongoing

Pharmacological Therapy: Hypertriglyceridaemia

Fibrates [10]

• Mechanism: PPAR-α agonists → increase lipoprotein lipase, reduce VLDL production
• Effects: Triglycerides ↓ 30-50%, HDL-C ↑ 10-20%, LDL-C ↑ 5-10% (may increase small dense LDL)
• Agents:
  • "Fenofibrate: 160 mg once daily (safer with statins than Gemfibrozil)"
  • "Bezafibrate: 400 mg once daily (modified release)"
• Indications:
  • Severe hypertriglyceridaemia (> 10 mmol/L) to reduce pancreatitis risk
  • Moderate hypertriglyceridaemia (> 5 mmol/L) with low HDL-C
  • Mixed dyslipidaemia despite statin therapy
• Evidence: Cardiovascular outcomes inconsistent
  • "FIELD, ACCORD Lipid trials: No significant reduction in primary endpoint"
  • Possible benefit in subgroup with high TG + low HDL-C
• Adverse Effects: Myopathy (especially with statin), GI upset, elevated creatinine (reversible), cholelithiasis
• Monitoring: LFTs, CK (especially with concomitant statin), eGFR

Omega-3 Fatty Acids (Icosapent Ethyl, Omega-3 Carboxylic Acids)

• Mechanism: Reduce hepatic VLDL synthesis
• TG Reduction: 20-40% (dose 2-4 g/day)
• Indications:
  • Severe hypertriglyceridaemia (adjunct to fibrate)
  • Hypertriglyceridaemia with cardiovascular disease
• Evidence:
  • "REDUCE-IT Trial (Icosapent Ethyl 4 g/day in patients with TG 1.5-5.6 mmol/L on statin): 5% absolute reduction in cardiovascular events"
  • Mechanism unclear (TG reduction alone vs pleiotropic anti-inflammatory effects)
• Adverse Effects: Fishy aftertaste, GI upset, increased bleeding risk (minor), atrial fibrillation (REDUCE-IT)

Management of Severe Hypertriglyceridaemia (> 10 mmol/L) [10]

1. Admit if Symptomatic (pancreatitis risk)
2. Fasting: Reduce chylomicron load
3. IV Fluids: Hydration
4. Insulin Infusion (if diabetes or very severe TG > 20 mmol/L): Activates lipoprotein lipase
5. Initiate Fibrate: Fenofibrate 160 mg once daily
6. Omega-3 Fatty Acids: 2-4 g/day
7. Identify and Treat Precipitants:
   • Uncontrolled diabetes (optimize glycaemic control)
   • Alcohol excess (abstinence)
   • Medications (stop oestrogen, isotretinoin, thiazides if possible)
   • Hypothyroidism (levothyroxine)
8. Long-Term:
   • Very low-fat diet (less than 15% total energy from fat)
   • Medium-chain triglycerides (absorbed directly, bypass chylomicron pathway)
   • Plasmapheresis if refractory

Treatment Targets

NICE Guidelines (UK) [5,6]

• Primary Target: ≥40% reduction in non-HDL-C from baseline
• No absolute LDL-C target specified (atorvastatin dose fixed)

ESC/EAS Guidelines (Europe) [1]

Management Algorithm

┌─────────────────────────────────────────────────────────────────┐
│                   DYSLIPIDAEMIA MANAGEMENT                        │
├─────────────────────────────────────────────────────────────────┤
│                                                                   │
│  STEP 1: ASSESS & CLASSIFY                                        │
│  ├─ Lipid profile (TC, LDL-C, HDL-C, TG, non-HDL-C)              │
│  ├─ Screen for secondary causes (TSH, glucose, eGFR, urinalysis) │
│  ├─ Assess for FH (Simon Broome/DLCN criteria)                   │
│  └─ Cardiovascular risk assessment:                               │
│     - Primary prevention: QRISK3                                  │
│     - Secondary prevention: Established ASCVD                     │
│                                                                   │
│  STEP 2: LIFESTYLE MODIFICATION (All patients, indefinite)        │
│  ├─ Diet: ↓ saturated fat, ↑ fibre, plant sterols                │
│  ├─ Exercise: ≥150 min/week moderate aerobic activity            │
│  ├─ Weight loss if BMI ≥25 kg/m²                                 │
│  ├─ Smoking cessation                                             │
│  └─ Alcohol moderation (especially if elevated TG)                │
│                                                                   │
│  STEP 3: STATIN THERAPY                                           │
│                                                                   │
│  PRIMARY PREVENTION (QRISK ≥10%):                                 │
│  └─ Atorvastatin 20 mg once daily                                │
│                                                                   │
│  SECONDARY PREVENTION (Established ASCVD):                        │
│  └─ Atorvastatin 80 mg once daily                                │
│                                                                   │
│  FAMILIAL HYPERCHOLESTEROLAEMIA:                                  │
│  └─ Atorvastatin 80 mg or Rosuvastatin 40 mg                     │
│                                                                   │
│  STEP 4: MONITOR AT 3 MONTHS                                      │
│  ├─ Lipid profile, LFTs                                           │
│  ├─ Assess adherence, side effects                                │
│  └─ Target: ≥40% reduction in non-HDL-C (NICE)                   │
│            OR LDL-C less than 1.4-2.6 mmol/L (ESC/EAS, risk-dependent)    │
│                                                                   │
│  STEP 5: IF TARGET NOT ACHIEVED                                   │
│  ├─ Check adherence                                               │
│  ├─ Optimize lifestyle                                            │
│  ├─ Increase statin dose (if tolerated)                           │
│  └─ ADD EZETIMIBE 10 mg                                           │
│                                                                   │
│  STEP 6: IF STILL NOT AT TARGET (Very High Risk/FH)               │
│  └─ ADD PCSK9 INHIBITOR or INCLISIRAN                             │
│     (Evolocumab, Alirocumab, Inclisiran)                          │
│                                                                   │
│  STEP 7: STATIN INTOLERANCE                                       │
│  ├─ Rechallenge after washout                                     │
│  ├─ Try alternate statin or lower dose                            │
│  ├─ Alternate-day dosing                                          │
│  ├─ Ezetimibe monotherapy (LDL ↓ 20%)                            │
│  └─ Bempedoic acid + Ezetimibe (LDL ↓ 35-40%)                    │
│                                                                   │
│  SEVERE HYPERTRIGLYCERIDAEMIA (> 10 mmol/L):                       │
│  ├─ Admit if symptomatic (pancreatitis risk)                      │
│  ├─ Identify precipitants (alcohol, DM, meds)                     │
│  ├─ Very low-fat diet (less than 15% energy from fat)                      │
│  ├─ FENOFIBRATE 160 mg                                            │
│  ├─ Omega-3 fatty acids 2-4 g/day                                 │
│  └─ Insulin infusion if very severe (> 20 mmol/L)                  │
│                                                                   │
└─────────────────────────────────────────────────────────────────┘

Special Populations

Familial Hypercholesterolaemia [9]

• Start statin in childhood (age > 10, or 8-10 if severe)
• High-intensity statin (Atorvastatin 80 mg or Rosuvastatin 40 mg)
• Add Ezetimibe if LDL-C ≥4.0 mmol/L on maximally tolerated statin
• Add PCSK9 inhibitor if LDL-C ≥3.5 mmol/L despite statin + ezetimibe
• Homozygous FH: Lipoprotein apheresis every 1-2 weeks (LDL-C reduction 50-70%)
• Cascade Screening: Test all first-degree relatives (50% risk if heterozygous parent)

Chronic Kidney Disease

• Statin + Ezetimibe reduces cardiovascular events in CKD (SHARP trial)
• Atorvastatin 20 mg if eGFR less than 60 mL/min/1.73m²
• Avoid statins in dialysis patients (limited benefit in AURORA, 4D trials)
• Dose-adjust statins in severe CKD (rosuvastatin, atorvastatin)

Diabetes Mellitus

• Type 1 DM: Statin if age > 40, duration > 10 years, nephropathy, or other CVD risk factors
• Type 2 DM: QRISK-based or if age > 40
• Target LDL-C less than 1.8 mmol/L (high risk)

Elderly (> 75 years)

• Continue statin if already on treatment
• Primary prevention: Shared decision-making (limited trial data in very elderly)
• Start lower dose; titrate as tolerated

Pregnancy and Breastfeeding

• Contraindications: Statins, ezetimibe, fibrates (teratogenic)
• Stop 3 months before conception if planned pregnancy
• Continue lifestyle measures, bile acid sequestrants (if essential)
• LDL apheresis for homozygous FH

---

8. Complications

Complications of Dyslipidaemia

Atherosclerotic Cardiovascular Disease [2,3]

• Coronary Artery Disease: Angina, myocardial infarction, heart failure, sudden cardiac death
  • Risk proportional to LDL-C exposure (duration × magnitude)
  • "FH patients: 50% untreated men have CHD by age 50, women by age 60 [9]"
• Cerebrovascular Disease: Ischaemic stroke, transient ischaemic attack, vascular dementia
  • 20-25% reduction in stroke with statin therapy [11]
• Peripheral Arterial Disease: Intermittent claudication, critical limb ischaemia, amputation
• Aortic Disease: Aortic stenosis (Lp(a) association), abdominal aortic aneurysm

Acute Pancreatitis [10]

• Severe hypertriglyceridaemia (> 10 mmol/L) causes ~10% of acute pancreatitis cases
• Mechanism: Toxic free fatty acids from lipoprotein lipase-mediated TG hydrolysis in pancreas
• Mortality 10-30% in severe pancreatitis
• Recurrent episodes if hypertriglyceridaemia not controlled

Xanthomatous Complications

• Tendon xanthomas: Achilles tendon rupture (rare)
• Eruptive xanthomas: Pruritus
• Palmar xanthomas: Cosmetic

Complications of Lipid-Lowering Therapy

Statin-Related [14]

• Statin-Associated Muscle Symptoms (SAMS): 5-10% (often nocebo)
• Myopathy: CK > 10× ULN (0.1%)
• Rhabdomyolysis: CK > 40× ULN, myoglobinuria, acute kidney injury (1 in 10,000)
• Hepatotoxicity: ALT > 3× ULN (1-3%); usually transient
• New-Onset Diabetes: 9% over 4 years (absolute risk increase 0.2%/year)
  • Benefits outweigh risk in all but lowest-risk patients
• Intracranial Haemorrhage: Possible association with very low LDL-C (less than 1.3 mmol/L); controversial

Ezetimibe

• Minimal side effects (diarrhoea rare)

PCSK9 Inhibitors [7,8]

• Injection site reactions (3-5%)
• Nasopharyngitis, flu-like symptoms
• No safety concerns with very low LDL-C (less than 0.5 mmol/L) in trials

Fibrates [10]

• Myopathy (increased with concomitant statin)
• Cholelithiasis (cholesterol gallstones)
• Elevated creatinine (reversible)
• Drug interactions (warfarin potentiation)

Bempedoic Acid

• Hyperuricaemia (gout risk)
• Tendon rupture (rare)

---

9. Prognosis & Outcomes

Natural History of Untreated Dyslipidaemia

Familial Hypercholesterolaemia [9]

• Heterozygous FH (untreated):
  • "Men: 50% risk of coronary heart disease by age 50"
  • "Women: 30% risk of coronary heart disease by age 60"
  • 10-20 year earlier cardiovascular events compared to general population
• Homozygous FH (untreated):
  • Myocardial infarction in childhood/adolescence (often before age 20)
  • Death by age 30 if untreated
  • Aortic stenosis develops in 2nd-3rd decade

Polygenic Hypercholesterolaemia

• Gradual increase in cardiovascular risk proportional to LDL-C level and duration
• Each 1 mmol/L increase in LDL-C → 20-25% increase in cardiovascular events [11]

Severe Hypertriglyceridaemia

• Recurrent acute pancreatitis (high mortality each episode)
• Chronic pancreatitis (if recurrent)
• Diabetes mellitus (pancreatic insufficiency)

Outcomes with Treatment

Statin Therapy [11]

• Cardiovascular Event Reduction:
  • 22% reduction in major vascular events per 1 mmol/L LDL-C reduction
  • Consistent across primary and secondary prevention
  • Benefit proportional to absolute LDL-C reduction (not % reduction)
• Mortality Reduction:
  • 10% reduction in all-cause mortality per 1 mmol/L LDL-C reduction
  • Cardiovascular mortality reduced 20%
• Time to Benefit:
  • "Secondary prevention: Benefit evident within 6-12 months"
  • "Primary prevention: Benefit evident within 2 years"
  • Benefit increases over time (cumulative risk reduction)
• Number Needed to Treat (5 years):
  • "Secondary prevention: NNT 20 to prevent 1 major vascular event"
  • "High-risk primary prevention (QRISK > 20%): NNT 40"
  • "Moderate-risk primary prevention (QRISK 10-20%): NNT 100"

Intensive LDL-C Lowering (Statin + Ezetimibe + PCSK9 Inhibitor) [7,8,13]

• LDL-C can be reduced to less than 1.0 mmol/L
• Further 15-20% relative risk reduction in cardiovascular events beyond high-dose statin
• Absolute benefit proportional to baseline risk (greatest in very high-risk patients)
• No safety concerns with LDL-C less than 0.5 mmol/L (seen in neonates, hunter-gatherer populations)

Familial Hypercholesterolaemia with Treatment [9]

• Early initiation of statin therapy (childhood) normalizes life expectancy if LDL-C targets achieved
• Each year of delay in treatment initiation increases cardiovascular risk
• Cascade screening and early treatment of relatives prevents premature CVD

Severe Hypertriglyceridaemia [10]

• Fibrate therapy reduces pancreatitis risk
• Cardiovascular benefit of fibrates less clear (inconsistent trial results)
• Icosapent ethyl reduces cardiovascular events in high-risk patients with elevated TG

Prognostic Factors

Poor Prognosis (Higher Cardiovascular Risk)

• LDL-C > 5.0 mmol/L
• Homozygous FH (null mutations worse than defective mutations)
• Elevated Lipoprotein(a) > 50 mg/dL [12]
• Additional cardiovascular risk factors (diabetes, hypertension, smoking, family history)
• Established ASCVD (secondary prevention)
• Poor adherence to lipid-lowering therapy

Good Prognosis

• Early detection and treatment (especially FH in childhood)
• Achievement of LDL-C targets
• High HDL-C (protective, though HDL-raising therapies have not shown benefit in trials)
• Adherence to lifestyle and pharmacological interventions

---

10. Examination Focus (MRCP PACES / Clinical Viva)

Case Presentation Pearls

Scenario: "This 42-year-old man has been referred with total cholesterol of 9.2 mmol/L. Please examine his cardiovascular system."

Approach:

1. Greet patient, confirm age (young patient + high cholesterol = suspect FH)
2. General Inspection:
   • Xanthelasma (eyelids)
   • Corneal arcus (if less than 45 years, highly suggestive of FH)
3. Hands:
   • Palpate extensor tendons (MCP, PIP joints) for tendon xanthomas
   • Check palmar creases (palmar xanthomas = Type III dysbetalipoproteinaemia)
4. Arms:
   • Tuberous xanthomas (elbows)
   • Peripheral pulses (radial, brachial - assess for PAD)
5. Lower Limbs:
   • Achilles tendon (lateral view - most important sign):
     • Inspect for thickening
     • Palpate for nodules or xanthomas
   • Peripheral pulses (femoral, popliteal, DP, PT)
   • Assess for PAD (hair loss, skin changes, ulcers)
6. Cardiovascular Examination:
   • Carotid bruits (carotid stenosis)
   • Praecordium (scars, apex displacement, murmurs)
7. Abdomen (if time):
   • Hepatosplenomegaly (severe hypertriglyceridaemia)

Presentation:

"This is Mr. X, a 42-year-old gentleman. On general inspection, I note bilateral xanthelasma and corneal arcus. Examination of the hands reveals tendon xanthomas over the extensor tendons of the fingers. Most significantly, there are bilateral Achilles tendon xanthomas, palpable as firm nodules. Peripheral pulses are present and equal. Cardiovascular examination is otherwise unremarkable, with no carotid bruits or cardiac murmurs. There is no hepatosplenomegaly."

"My findings are consistent with Familial Hypercholesterolaemia. I would like to proceed by:"

• "Taking a focused history to assess for premature cardiovascular disease in the patient or family members"
• "Reviewing lipid profile and calculating Dutch Lipid Clinic Network (DLCN) score"
• "Arranging genetic testing (LDLR, APOB, PCSK9 mutations)"
• "Initiating high-intensity statin therapy (Atorvastatin 80 mg) with target LDL-C reduction ≥50%"
• "Cascade screening of first-degree relatives"
• "Assessing for established cardiovascular disease (ECG, consider stress testing or CT calcium score)"

Viva Questions and Model Answers

Q1: What are the diagnostic criteria for Familial Hypercholesterolaemia?

A1: "There are two main clinical criteria used in the UK:"

"Simon Broome Criteria:"

• "Definite FH requires total cholesterol > 7.5 mmol/L or LDL-C > 4.9 mmol/L in adults, plus tendon xanthomas in the patient or a first- or second-degree relative."
• "Possible FH requires the same cholesterol levels plus either a family history of MI before age 60 in a first-degree relative or before 50 in a second-degree relative, or a family history of total cholesterol > 7.5 mmol/L."

"Dutch Lipid Clinic Network (DLCN) uses a point-based system incorporating:"

• "Family history of premature CVD or hypercholesterolaemia"
• "Personal history of premature CVD"
• "Physical examination findings (tendon xanthomas 6 points, arcus less than 45 years 4 points)"
• "LDL-C levels (8 points for ≥8.5 mmol/L)"
• "Genetic testing (8 points if mutation found)"
• "A score > 8 indicates definite FH, 6-8 probable FH, 3-5 possible FH."

"Additionally, genetic testing for LDLR, APOB, and PCSK9 mutations confirms diagnosis and enables cascade screening of relatives."

---

Q2: How would you manage a patient with newly diagnosed FH?

A2: "Management of FH requires a comprehensive, lifelong approach:"

"1. Confirm Diagnosis:"

• "Review lipid profile (ideally pre-treatment)"
• "Calculate DLCN score"
• "Arrange genetic testing (LDLR, APOB, PCSK9)"

"2. Risk Stratification:"

• "Assess for established ASCVD (history, ECG, consider stress test or CT calcium score)"
• "Screen for additional cardiovascular risk factors (diabetes, hypertension, smoking)"
• "Check Lipoprotein(a) - elevated Lp(a) increases risk further in FH"

"3. Initiate High-Intensity Statin:"

• "Start Atorvastatin 80 mg or Rosuvastatin 40 mg"
• "Target: ≥50% reduction in LDL-C from baseline"
• "If child (age > 10), start Atorvastatin 10-20 mg and titrate"

"4. Lifestyle Modification:"

• "Dietary advice: reduce saturated fat less than 7% total energy, increase soluble fibre, plant sterols 2 g/day"
• "Regular aerobic exercise, smoking cessation, weight management"

"5. Add-On Therapy if Targets Not Met (LDL-C ≥4.0 mmol/L despite maximally tolerated statin):"

• "Add Ezetimibe 10 mg"
• "If still not at target (LDL-C ≥3.5 mmol/L): Add PCSK9 inhibitor (Evolocumab, Alirocumab) or Inclisiran"

"6. Cascade Screening:"

• "Test all first-degree relatives (50% will have FH if parent heterozygous)"
• "Genetic testing enables predictive testing in children and relatives"

"7. Long-Term Monitoring:"

• "Lipid profile and LFTs at 3 months, then annually"
• "Assess adherence, side effects"
• "Screen for cardiovascular disease (BP, ECG, consider periodic imaging)"

---

Q3: A patient on high-dose atorvastatin complains of muscle aches. How would you approach this?

A3: "Statin-associated muscle symptoms (SAMS) are common (~5-10%) but often multifactorial. My approach would be:"

"1. Assess Severity:"

• "Mild myalgia (aches, stiffness) without weakness?"
• "Or true myopathy (weakness, reduced function)?"
• "Timing: Related to statin initiation/dose increase?"

"2. Investigations:"

• "Creatine Kinase (CK): Crucial to differentiate myalgia (CK normal) from myopathy (CK > 10× ULN) or rhabdomyolysis (CK > 40× ULN)"
• "Exclude other causes: TSH (hypothyroidism), vitamin D (deficiency common), eGFR (renal impairment)"
• "Review concomitant medications (drug interactions: CYP3A4 inhibitors with atorvastatin)"

"3. Management Based on CK:"

• "CK normal (less than 5× ULN): Reassure, exclude other causes, consider rechallenge after 2-week washout (symptoms may be nocebo)"
• "CK 5-10× ULN, mild symptoms: Reduce statin dose or switch to alternate statin (e.g., rosuvastatin, pravastatin)"
• "CK > 10× ULN (myopathy): Stop statin immediately, recheck CK weekly until normalizes"
• "CK > 40× ULN (rhabdomyolysis): Stop statin, admit, IV fluids, monitor renal function, urine for myoglobinuria"

"4. Re-Introduction Strategies (if CK normalizes):"

• "Lower dose of same statin"
• "Alternate statin (different metabolism: rosuvastatin, pravastatin have fewer CYP interactions)"
• "Alternate-day dosing (atorvastatin has long half-life)"
• "If intolerant to all statins: Ezetimibe monotherapy (LDL-C ↓ 20%) or Bempedoic acid + Ezetimibe (LDL-C ↓ 35-40%)"

"5. Continue Treatment:"

• "Emphasize cardiovascular benefit far outweighs myalgia risk"
• "True rhabdomyolysis is very rare (1 in 10,000)"
• "Most muscle symptoms resolve or improve with dose adjustment or alternate statin"

---

Q4: What is the evidence for PCSK9 inhibitors?

A4: "PCSK9 inhibitors are monoclonal antibodies that reduce LDL-C by 50-60% by preventing PCSK9-mediated degradation of LDL receptors. Two landmark trials established their cardiovascular benefit:"

"FOURIER Trial (2017):"

• "27,564 patients with ASCVD on statin therapy randomized to Evolocumab vs placebo"
• "Median follow-up 2.2 years"
• "LDL-C reduced from 2.4 mmol/L to 0.78 mmol/L"
• "Results: 15% relative risk reduction in primary composite endpoint (CV death, MI, stroke, hospitalization for unstable angina, coronary revascularization)"
• "1.5% absolute risk reduction (NNT 67 over 2.2 years)"
• "No increase in adverse events, including neurocognitive effects despite very low LDL-C"

"ODYSSEY OUTCOMES Trial (2018):"

• "18,924 patients post-ACS (1-12 months) on high-intensity statin randomized to Alirocumab vs placebo"
• "Median follow-up 2.8 years"
• "LDL-C reduced from 2.4 mmol/L to 1.3 mmol/L (vs 2.9 mmol/L placebo)"
• "Results: 15% relative risk reduction in composite endpoint (CV death, MI, stroke, unstable angina)"
• "1.6% absolute risk reduction (NNT 63 over 2.8 years)"
• "Mortality benefit in subgroup with baseline LDL-C ≥2.6 mmol/L"

"Clinical Implications:"

• "PCSK9 inhibitors reduce cardiovascular events when added to maximally tolerated statin therapy"
• "Benefit proportional to baseline risk (greatest in very high-risk patients: post-ACS, FH, recurrent events)"
• "NICE restricts use due to cost (~£4,000-5,000/year): approved for LDL-C ≥4.0 mmol/L (secondary prevention) or ≥5.0 mmol/L (high-risk primary prevention) despite statin + ezetimibe"
• "Inclisiran (siRNA targeting PCSK9) offers similar efficacy with twice-yearly dosing (improved adherence)"

---

Q5: Explain the pathophysiology of atherosclerosis in relation to LDL cholesterol.

A5: "Atherosclerosis is a chronic inflammatory disease of the arterial wall driven by LDL cholesterol accumulation:"

"1. Endothelial Dysfunction:"

• "Cardiovascular risk factors (hypertension, smoking, diabetes, dyslipidaemia) → endothelial injury and increased permeability"

"2. LDL Retention:"

• "Circulating LDL particles cross the endothelium into the subendothelial space (intima)"
• "LDL binds to proteoglycans in the extracellular matrix, becoming trapped"

"3. LDL Modification:"

• "Trapped LDL undergoes oxidation, glycation, and enzymatic modification → oxidized LDL (oxLDL)"

"4. Inflammatory Response:"

• "OxLDL activates endothelial cells → expression of adhesion molecules (VCAM-1, ICAM-1)"
• "Monocyte recruitment, adhesion, and migration into intima"
• "Monocyte differentiation to macrophages"

"5. Foam Cell Formation:"

• "Macrophages express scavenger receptors (CD36, SR-A, LOX-1) which recognize and internalize oxLDL"
• "Unlike LDL receptors, scavenger receptors lack negative feedback → unregulated uptake"
• "Cholesteryl ester accumulation → lipid-laden macrophages = foam cells"

"6. Fatty Streak:"

• "Earliest visible lesion: subendothelial accumulation of foam cells"

"7. Plaque Progression:"

• "Smooth muscle cell migration from media to intima, proliferation, and extracellular matrix synthesis"
• "Fibrous cap formation (collagen, elastin) overlying a lipid-rich necrotic core (from foam cell death)"
• "Calcification, neovascularization"

"8. Plaque Rupture:"

• "Thin-cap fibroatheroma vulnerable to rupture (matrix metalloproteinases degrade collagen)"
• "Rupture exposes thrombogenic necrotic core → platelet activation, thrombus formation"
• "Acute clinical events: Myocardial infarction, stroke, acute limb ischaemia"

"Causal Role of LDL:"

• "Mendelian randomization studies and genetic evidence (FH, PCSK9 mutations) confirm LDL-C as causally related to atherosclerosis"
• "Lifelong LDL-C lowering (genetic or pharmacological) reduces cardiovascular events proportional to absolute LDL-C reduction"
• "'Lower is better' principle: No lower threshold for LDL-C safety identified"

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Q6: A 28-year-old woman with total cholesterol of 11 mmol/L is planning pregnancy. How would you manage her dyslipidaemia?

A6: "This scenario likely represents Familial Hypercholesterolaemia in a woman of reproductive age. Management must balance cardiovascular risk reduction with teratogenicity concerns:"

"Pre-Conception Phase (Current):"

1. "Confirm FH diagnosis: DLCN criteria, genetic testing (LDLR, APOB, PCSK9)"
2. "Risk stratification: Assess for existing ASCVD (ECG, consider stress test or CT calcium score), check Lp(a)"
3. "Optimize lipid lowering NOW (before pregnancy):"
   • "High-intensity statin (Atorvastatin 80 mg or Rosuvastatin 40 mg) + Ezetimibe"
   • "Target ≥50% LDL-C reduction"
   • "Consider PCSK9 inhibitor if very high risk and LDL-C remains elevated"
4. "Lifestyle modification: Diet, exercise, weight optimization"

"Planning for Pregnancy:"

1. "Stop teratogenic medications 3 months before conception:"
   • "Discontinue statin, ezetimibe, fibrates (all contraindicated in pregnancy)"
   • "PCSK9 inhibitors: Limited data, generally avoid"
2. "Continue safe therapy:"
   • "Bile acid sequestrants (Colesevelam) are safe (not absorbed systemically) but poorly tolerated (constipation, bloating)"
   • "Lifestyle measures (dietary modification, exercise)"
3. "Pre-pregnancy counseling:"
   • "Explain lipid-lowering therapy interruption during pregnancy and breastfeeding (~2 years off treatment)"
   • "Small increase in cardiovascular risk during this period, but absolute risk low at age 28"
   • "Reassure: Most FH women tolerate pregnancy well without acute events"

"During Pregnancy:"

• "Monitor lipids (expect physiological increase in cholesterol and triglycerides)"
• "Maintain lifestyle measures"
• "If homozygous FH or very high-risk (prior MI): Consider LDL apheresis (every 2 weeks) - safe in pregnancy"

"Postpartum:"

• "Avoid statins if breastfeeding (excreted in breast milk)"
• "Resume statins after cessation of breastfeeding (typically 6-12 months postpartum)"
• "Restart high-intensity statin + ezetimibe"
• "Repeat lipid profile 3 months after restarting therapy"

"Long-Term:"

• "Cascade screening: Test child at age > 2 years (genetic testing if parental mutation known, otherwise lipid profile at age 5-10)"
• "Emphasize importance of lifelong lipid management to prevent premature cardiovascular disease"

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11. Patient/Layperson Explanation

What is Dyslipidaemia?

Dyslipidaemia means you have abnormal levels of fats (lipids) in your blood. The most important type is cholesterol. Think of cholesterol as a waxy substance that travels through your bloodstream. Your body needs some cholesterol for normal function, but too much of the wrong type can cause problems.

There are different types of cholesterol:

• LDL cholesterol ("bad cholesterol"): This is the harmful type. High levels cause fatty deposits to build up inside your arteries, narrowing them and making it harder for blood to flow. Over time, this can lead to heart attacks and strokes.
• HDL cholesterol ("good cholesterol"): This is protective. It helps remove excess cholesterol from your arteries and takes it back to your liver for disposal.
• Triglycerides: Another type of fat in your blood. Very high levels (especially above 10 mmol/L) can cause inflammation of your pancreas, which is very painful and potentially dangerous.

What Causes High Cholesterol?

There are several reasons why cholesterol levels might be high:

1. Diet: Eating too much saturated fat (found in butter, cheese, fatty meat, pastries, cakes) raises LDL cholesterol.
2. Lack of exercise: Being inactive lowers your good (HDL) cholesterol and can raise triglycerides.
3. Being overweight: Excess weight, especially around your waist, worsens cholesterol levels.
4. Genetics: Some people inherit genes that cause very high cholesterol from birth. This is called Familial Hypercholesterolaemia (FH). About 1 in 250 people have FH, but most don't know it. If you have FH, your cholesterol might be 8, 9, or even 10+ mmol/L without treatment.
5. Other medical conditions: Conditions like an underactive thyroid (hypothyroidism), diabetes, or kidney disease can raise cholesterol.
6. Age and sex: Cholesterol tends to rise as you get older. Before menopause, women usually have lower cholesterol than men.

How Do I Know If I Have High Cholesterol?

High cholesterol has no symptoms. You can't feel it. The only way to know is through a blood test.

Your doctor will measure:

• Total cholesterol: Should be below 5 mmol/L
• LDL cholesterol: Should be below 3 mmol/L (lower if you're high risk)
• HDL cholesterol: Should be above 1 mmol/L (men) or 1.2 mmol/L (women)
• Triglycerides: Should be below 1.7 mmol/L

If your cholesterol is very high (e.g., total cholesterol > 7.5 mmol/L), especially if you're young or have a family history of early heart disease, your doctor may suspect Familial Hypercholesterolaemia. They might check for physical signs like:

• Tendon xanthomas: Small lumps in the tendons of your hands or Achilles tendon (back of ankle)
• Xanthelasma: Yellow patches on your eyelids
• Corneal arcus: A white or grey ring around the edge of your eye

How is High Cholesterol Treated?

1. Lifestyle Changes (Everyone)

These are the foundation of treatment and can lower your cholesterol by 10-20%:

• Healthy diet:
  • Reduce saturated fat (fatty meat, butter, cheese, cakes, pastries)
  • Eat more fibre (oats, beans, lentils, fruits, vegetables)
  • Include healthy fats (olive oil, nuts, oily fish like salmon and mackerel)
  • Add plant sterols (found in fortified spreads and yogurts) - 2g per day can lower cholesterol by 10%
• Exercise regularly: At least 150 minutes per week (e.g., 30 minutes walking, 5 days a week)
• Lose weight if overweight: Even 5-10% weight loss helps
• Stop smoking: Smoking lowers good (HDL) cholesterol and damages your arteries
• Limit alcohol: Too much alcohol raises triglycerides

2. Medication

If lifestyle changes aren't enough, or if your risk of heart disease or stroke is high, your doctor will prescribe medication:

Statins (most common):

• Examples: Atorvastatin, Simvastatin, Rosuvastatin
• How they work: Stop your liver from making as much cholesterol, so your body removes more cholesterol from your blood
• How effective: Lower LDL cholesterol by 30-55% (depending on type and dose)
• Benefits: Reduce your risk of heart attack and stroke by 20-35%
• How to take: One tablet each evening (your liver makes most cholesterol at night)
• Are statins safe? Yes, for most people. Side effects are uncommon:
  • "Muscle aches: Affect 5-10% of people. Usually mild. Serious muscle damage is very rare (1 in 10,000)."
  • "Liver changes: Very rare. Your doctor will check blood tests."
  • "Diabetes: Slight increase in diabetes risk, but the heart benefits far outweigh this small risk."
  • Many people worry about side effects they've read about online. In studies where people didn't know if they were taking a statin or a fake pill (placebo), both groups reported similar rates of side effects. This means many symptoms blamed on statins are actually due to other causes or the "nocebo effect" (expecting side effects makes you more likely to feel them).

Ezetimibe:

• Added to statin if cholesterol still too high
• Blocks cholesterol absorption from your gut
• Lowers cholesterol by an extra 15-20%

PCSK9 Inhibitors (e.g., Evolocumab, Alirocumab):

• Given as an injection every 2 weeks or monthly
• Used if cholesterol remains very high despite statins and ezetimibe, or if you can't tolerate statins
• Very powerful: Lower cholesterol by 50-60%
• Expensive (£4,000-5,000 per year), so only used in very high-risk patients

Fibrates (for very high triglycerides):

• Used if triglycerides are very high (> 10 mmol/L) to prevent pancreas inflammation

3. How Long Do I Need Treatment?

• Most people need lifelong treatment.
• High cholesterol is usually a chronic condition (especially if genetic).
• Stopping medication causes cholesterol to rise again, increasing your heart attack and stroke risk.
• Think of it like wearing glasses: They work while you use them, but if you stop, the problem returns.

What Happens If I Don't Treat High Cholesterol?

Over many years, untreated high cholesterol causes fatty deposits (called plaques) to build up inside your arteries. This process is called atherosclerosis or "hardening of the arteries."

These plaques:

• Narrow your arteries, reducing blood flow
• Can rupture (burst), causing a blood clot to form
• Lead to serious problems:
  • "Heart attack: Blocked artery in the heart"
  • "Stroke: Blocked artery in the brain"
  • "Peripheral arterial disease: Blocked arteries in your legs (causing pain when walking)"

If you have Familial Hypercholesterolaemia and don't get treatment:

• Men have a 50% chance of a heart attack by age 50
• Women have a 30% chance of a heart attack by age 60
• This is 10-20 years earlier than the general population

With treatment, people with FH can live a normal, healthy life.

What About My Family?

If you have Familial Hypercholesterolaemia, there's a 50% chance each of your children and siblings also have it (it's inherited from one parent).

Your doctor will recommend "cascade screening":

• Your close family members (parents, siblings, children) should have their cholesterol checked
• If a genetic test finds the specific mutation causing your FH, relatives can have a simple genetic test
• Finding and treating FH early in relatives prevents heart attacks and strokes

Key Takeaways

1. High cholesterol has no symptoms - you need a blood test to know you have it.
2. High LDL ("bad") cholesterol causes heart attacks and strokes over time.
3. Lifestyle changes (diet, exercise, weight loss, not smoking) help lower cholesterol.
4. Statins are very effective and safe for most people - they reduce your risk of heart attack and stroke by 20-35%.
5. Treatment is usually lifelong.
6. If you have Familial Hypercholesterolaemia, your family should be tested too.

The good news: With treatment, you can lower your cholesterol, protect your heart and blood vessels, and reduce your risk of serious problems. The earlier you start treatment, the better the results.

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12. Evidence & Guidelines

Key Guidelines

1. NICE CG181: Cardiovascular Disease: Risk Assessment and Reduction, Including Lipid Modification. Updated 2023.

   • NICE CG181

2. NICE NG238: Cardiovascular Disease Prevention. 2023.

   • NICE NG238

3. NICE CG71: Familial Hypercholesterolaemia: Identification and Management. 2019.

   • NICE CG71

4. ESC/EAS Guidelines: 2019 ESC/EAS Guidelines for the Management of Dyslipidaemias. European Heart Journal 2020; 41(1):111-188.

   • DOI: 10.1093/eurheartj/ehz455

5. ACC/AHA Guideline: 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Blood Cholesterol. Circulation 2019; 139(25):e1082-e1143.

   • DOI: 10.1161/CIR.0000000000000625

Key Evidence

Statin Therapy

[1] Mach F, et al. 2019 ESC/EAS Guidelines for the management of dyslipidaemias: lipid modification to reduce cardiovascular risk. Eur Heart J. 2020;41(1):111-188. PMID: 31504418. DOI: 10.1093/eurheartj/ehz455

[2] Roth GA, et al. Global Burden of Cardiovascular Diseases and Risk Factors, 1990-2019. J Am Coll Cardiol. 2020;76(25):2982-3021. PMID: 33309175. DOI: 10.1016/j.jacc.2020.11.010

[3] Ference BA, et al. Low-density lipoproteins cause atherosclerotic cardiovascular disease. 1. Evidence from genetic, epidemiologic, and clinical studies. A consensus statement from the European Atherosclerosis Society Consensus Panel. Eur Heart J. 2017;38(32):2459-2472. PMID: 28444290. DOI: 10.1093/eurheartj/ehx144

[4] Jellinger PS, et al. American Association of Clinical Endocrinologists and American College of Endocrinology Guidelines for Management of Dyslipidemia and Prevention of Cardiovascular Disease. Endocr Pract. 2017;23(Suppl 2):1-87. PMID: 28437620. DOI: 10.4158/EP171764.APPGL

[5] Hippisley-Cox J, et al. Development and validation of QRISK3 risk prediction algorithms to estimate future risk of cardiovascular disease: prospective cohort study. BMJ. 2017;357:j2099. PMID: 28536104. DOI: 10.1136/bmj.j2099

[6] National Institute for Health and Care Excellence (NICE). Cardiovascular disease: risk assessment and reduction, including lipid modification. Clinical guideline [CG181]. 2014, updated 2023.

[7] Sabatine MS, et al. (FOURIER Trial). Evolocumab and Clinical Outcomes in Patients with Cardiovascular Disease. N Engl J Med. 2017;376(18):1713-1722. PMID: 28304224. DOI: 10.1056/NEJMoa1615664

[8] Schwartz GG, et al. (ODYSSEY OUTCOMES Trial). Alirocumab and Cardiovascular Outcomes after Acute Coronary Syndrome. N Engl J Med. 2018;379(22):2097-2107. PMID: 30403574. DOI: 10.1056/NEJMoa1801174

[9] Nordestgaard BG, et al. Familial hypercholesterolaemia is underdiagnosed and undertreated in the general population: guidance for clinicians to prevent coronary heart disease. Eur Heart J. 2013;34(45):3478-90. PMID: 23956253. DOI: 10.1093/eurheartj/eht273

[10] Berglund L, et al. Evaluation and Treatment of Hypertriglyceridemia: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2012;97(9):2969-2989. PMID: 22962670. DOI: 10.1210/jc.2011-3213

[11] Cholesterol Treatment Trialists' (CTT) Collaboration. Efficacy and safety of more intensive lowering of LDL cholesterol: a meta-analysis of data from 170,000 participants in 26 randomised trials. Lancet. 2010;376(9753):1670-1681. PMID: 21067804. DOI: 10.1016/S0140-6736(10)61350-5

[12] Tsimikas S. A Test in Context: Lipoprotein(a): Diagnosis, Prognosis, Controversies, and Emerging Therapies. J Am Coll Cardiol. 2017;69(6):692-711. PMID: 28183512. DOI: 10.1016/j.jacc.2016.11.042

[13] Cannon CP, et al. (IMPROVE-IT Trial). Ezetimibe Added to Statin Therapy after Acute Coronary Syndromes. N Engl J Med. 2015;372(25):2387-2397. PMID: 26039521. DOI: 10.1056/NEJMoa1410489

[14] Stroes ES, et al. Statin-associated muscle symptoms: impact on statin therapy—European Atherosclerosis Society Consensus Panel Statement on Assessment, Aetiology and Management. Eur Heart J. 2015;36(17):1012-1022. PMID: 25694464. DOI: 10.1093/eurheartj/ehv043

[15] Sniderman AD, et al. Familial combined hyperlipidemia: a pathophysiologic and genetic perspective. Curr Opin Lipidol. 2002;13(1):25-30. PMID: 11790960. DOI: 10.1097/00041433-200202000-00005

[16] Eckel RH, et al. 2013 AHA/ACC Guideline on Lifestyle Management to Reduce Cardiovascular Risk. Circulation. 2014;129(25 Suppl 2):S76-99. PMID: 24222015. DOI: 10.1161/01.cir.0000437740.48606.d1

Additional Key Trials (Referenced in Text)

[17] Nissen SE, et al. (ACCELERATE Trial). Effects of a Potent and Selective PPAR-α Agonist in Patients With Atherogenic Dyslipidemia or Hypertriglyceridemia: Two Randomized Controlled Trials. JAMA. 2007;297(12):1362-1373. PMID: 17384436. DOI: 10.1001/jama.297.12.1362

[18] Bhatt DL, et al. (REDUCE-IT Trial). Cardiovascular Risk Reduction with Icosapent Ethyl for Hypertriglyceridemia. N Engl J Med. 2019;380(1):11-22. PMID: 30415628. DOI: 10.1056/NEJMoa1812792

[19] Nissen SE, et al. (CLEAR Outcomes Trial). Bempedoic Acid and Cardiovascular Outcomes in Statin-Intolerant Patients. N Engl J Med. 2023;388(15):1353-1364. PMID: 36876740. DOI: 10.1056/NEJMoa2215024

[20] Ray KK, et al. (ORION-10 and ORION-11 Trials). Two Phase 3 Trials of Inclisiran in Patients with Elevated LDL Cholesterol. N Engl J Med. 2020;382(16):1507-1519. PMID: 32187462. DOI: 10.1056/NEJMoa1912387

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13. Summary Tables

Lipoprotein Classes

Genetic Dyslipidaemias

Statin Comparison

Treatment Targets by Risk Category (ESC/EAS 2019)

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