Coronary Artery Disease — Written Clinical Reasoning

SAQ 1 — Integrated Management of NSTEMI (20 marks, 30 minutes)

Prompt: Outline your immediate and integrated management plan for this patient, including acute pharmacotherapy, reperfusion strategy, secondary prevention, and comorbidity optimisation. Justify each decision with reference to evidence and risk stratification. [1]

Model Answer

Problem list (4 marks):

1. High-risk non-ST-elevation myocardial infarction (NSTEMI) — GRACE 165, dynamic ST depression, troponin rise/fall
2. Type 2 diabetes (HbA1c 72 mmol/mol) — under-optimised, high cardiovascular risk
3. Hyperlipidaemia — on sub-target statin dose (atorvastatin 40mg, not high-intensity)
4. Ongoing tobacco dependence (40 pack-years)
5. Hypertension (BP 150/90 on amlodipine)
6. Likely multivessel coronary disease — will require heart team assessment (diabetic) [1]

Immediate management — acute pharmacotherapy (6 marks): [1]

Reperfusion strategy (3 marks):

• This patient is high-risk NSTE-ACS (GRACE >140, troponin rise/fall, dynamic ST depression). He is NOT very-high-risk (no haemodynamic compromise, refractory angina, cardiac arrest, mechanical complications, or acute heart failure).
• Indication: coronary angiography within 24 hours, with PCI to the culprit lesion if indicated.
• If angiography reveals multivessel disease (likely given diabetes and extensive risk factors), involve the heart team for CABG vs PCI decision. As a diabetic with potential complex disease, CABG may be favoured (SYNTAX and FREEDOM evidence) [3].

Secondary prevention plan (4 marks): [1]

Comorbidity optimisation (2 marks):

• Diabetes: SGLT2 inhibitor addresses both glycaemic control and cardiovascular protection. Consider GLP-1 receptor agonist (semaglutide) for additional CV benefit and weight management. Continue metformin; review gliclazide (hypoglycaemia risk if adding SGLT2i).
• Blood pressure: Target below 130/80. ACE inhibitor + beta-blocker will help; titrate as outpatient.
• Renal function: Monitor with ACEi initiation and contrast exposure; acceptable creatinine rise up to 30%. [1]

Communication and follow-up (1 mark):

• Cardiac rehabilitation referral for structured exercise and education.
• Medication adherence counselling — explain that the 12-month DAPT is essential to prevent stent thrombosis.
• Advance care planning discussion appropriate at follow-up if LV dysfunction is confirmed.
• GP follow-up for cardiovascular risk factor optimisation. [1]

SAQ 2 — Investigation Interpretation (12 marks, 20 minutes)

Prompt: A 74-year-old woman presents with 1 hour of severe central chest pain radiating to the jaw and associated with diaphoresis. The ECG shows 2 mm ST elevation in leads II, III, and aVF, with 1 mm ST elevation in V1 and ST depression in I and aVL. Blood pressure is 100/65. Interpret the ECG, identify the culprit artery and territory, and outline the immediate management including reperfusion decisions. [1]

Model Answer

ECG interpretation (4 marks):

• ST elevation in II, III, aVF indicates an acute inferior STEMI.
• ST elevation in V1 in the context of inferior STEMI suggests right ventricular involvement — the culprit is a proximal right coronary artery (RCA) occlusion above the RV marginal branch.
• ST depression in I and aVL is reciprocal change, supporting the diagnosis of true STEMI rather than a mimic.
• Right-sided leads (V4R) should be recorded to confirm RV infarction (ST elevation in V4R is diagnostic). [1]

Culprit artery and territory (2 marks):

• Proximal RCA occlusion causing inferior and right ventricular infarction. The RV marginal branches arise from the proximal RCA; occlusion above their origin causes RV infarction, which has important management implications. [1]

Immediate management — specific to RV infarction (4 marks):

1. Reperfusion: This is a STEMI — activate the catheter lab for primary PCI (door-to-balloon ≤90 min). If PCI is not available within 120 minutes, fibrinolysis is indicated (no contraindications given).
2. Avoid nitrates and diuretics: RV infarction is preload-dependent. Nitrates reduce preload and can precipitate profound hypotension. If hypotension occurs, treat with IV fluid bolus (normal saline) to maintain RV filling.
3. Standard STEMI drug therapy: Aspirin 300 mg, ticagrelor 180 mg, heparin, atorvastatin 80 mg.
4. Atropine for bradycardia/heart block: The RCA supplies the AV node; inferior MI commonly causes bradycardia and AV block. Atropine 0.5 mg IV for symptomatic bradycardia; temporary pacing wire if high-grade AV block with instability. [1]

Prognostic considerations (2 marks):

• RV infarction increases in-hospital mortality compared to isolated inferior MI (due to cardiogenic shock risk).
• Monitor in a coronary care unit for bradyarrhythmias, AV block, and hypotension.
• Complete heart block in inferior MI is usually transient (AV node ischaemia) and resolves with reperfusion, unlike anterior MI heart block which often requires a permanent pacemaker. [1]