Perioperative Myocardial Infarction

Overview

Perioperative myocardial infarction (PMI) represents acute myocardial injury occurring within 30 days of surgery, resulting from myocardial ischemia with evidence of myocardial necrosis. It constitutes one of the most serious cardiovascular complications following noncardiac surgery, with significant implications for both short-term and long-term mortality. [1,2]

The entity encompasses both traditional Type 1 myocardial infarction (plaque rupture) and Type 2 infarction (supply-demand mismatch), with the latter predominating in the perioperative period due to surgical stress, hemodynamic fluctuations, anemia, and increased metabolic demands. [3] The majority of perioperative myocardial infarctions occur within the first 48 hours postoperatively and are frequently clinically silent, detected only through systematic troponin surveillance. [4]

Contemporary understanding distinguishes perioperative myocardial infarction from the broader category of Myocardial Injury after Noncardiac Surgery (MINS), with PMI requiring evidence of acute ischemia in addition to troponin elevation. [5] This distinction has profound therapeutic and prognostic implications, as PMI carries a 30-day mortality of 10-15% compared to 3-5% for isolated MINS. [6]

⚠️ Red Flag: Critical Safety Points:

• Most perioperative MIs are clinically silent (> 65%), requiring systematic troponin surveillance in high-risk patients
• Presentation without chest pain is the norm, not the exception
• 30-day mortality exceeds 10%, similar to non-surgical acute MI
• Withholding antiplatelet therapy without clear bleeding risk may increase MI incidence

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Epidemiology

Perioperative myocardial infarction affects approximately 1-5% of patients undergoing noncardiac surgery, with incidence varying substantially based on surgical population risk profile and diagnostic criteria employed. [7]

Risk Factors

Patient-Related Factors (Revised Cardiac Risk Index - RCRI): [12]

1. History of ischemic heart disease
2. History of cerebrovascular disease
3. History of congestive heart failure
4. Insulin-dependent diabetes mellitus
5. Preoperative serum creatinine > 2.0 mg/dL (177 μmol/L)
6. High-risk surgery (intraperitoneal, intrathoracic, or suprainguinal vascular)

RCRI Score Interpretation:

• 0 factors: 0.4% risk of major cardiac events
• 1 factor: 0.9% risk
• 2 factors: 6.6% risk
• ≥3 factors: > 11% risk

The RCRI remains the most validated preoperative risk prediction tool, though newer biomarker-based models incorporating NT-proBNP and high-sensitivity troponin demonstrate superior discrimination (C-statistic 0.75 vs 0.67). [13]

Surgical Factors:

• Emergency surgery (3-5× increased risk)
• Prolonged surgery (> 3 hours)
• Major blood loss (> 500 mL)
• Intraoperative hypotension (MAP less than 55-60 mmHg for > 10 minutes)

Demographic Patterns:

• Age > 65 years: 2-3× increased incidence
• Male sex: 1.3-1.5× increased risk
• No significant ethnic variation reported in adjusted analyses

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Aetiology & Pathophysiology

Causes

Perioperative myocardial infarction arises from distinct pathophysiological mechanisms compared to spontaneous MI:

Type 1 MI (Plaque Rupture) - 20-30% of cases:

• Atherosclerotic plaque rupture with acute thrombosis
• Triggered by:
  • Hemodynamic stress and tachycardia
  • Hypercoagulability (surgical trauma, inflammatory response)
  • Catecholamine surge
  • Prothrombotic state (increased fibrinogen, factor VIII, platelet activation)

Type 2 MI (Supply-Demand Mismatch) - 60-70% of cases:

• Myocardial oxygen supply-demand imbalance
• Causes:
  • Intraoperative hypotension (especially MAP less than 55 mmHg)
  • Tachycardia (reducing diastolic filling time)
  • Anemia (Hb less than 70-80 g/L)
  • Hypoxemia
  • Increased metabolic demands (pain, shivering, infection)
  • Coronary vasospasm

Type 4 MI (PCI-related) and Type 5 MI (CABG-related):

• Apply to cardiac surgery only
• Require specific diagnostic criteria (troponin elevation > 10× or 35× ULN respectively)

Pathophysiology

Exam Detail: Molecular Mechanisms:

1. Hemodynamic Stress Response:

   • Surgical stress activates hypothalamic-pituitary-adrenal (HPA) axis
   • Increased cortisol and catecholamines (epinephrine, norepinephrine)
   • Results in tachycardia, hypertension, increased myocardial work
   • Elevated heart rate-blood pressure product increases oxygen demand

2. Inflammatory Response:

   • Surgical tissue injury triggers systemic inflammatory response syndrome (SIRS)
   • Cytokine release (IL-6, IL-8, TNF-α) promotes plaque instability
   • C-reactive protein (CRP) elevation within 6-24 hours
   • Endothelial dysfunction and microvascular injury

3. Hypercoagulable State:

   • Increased procoagulant factors (fibrinogen, factor VIII, von Willebrand factor)
   • Enhanced platelet activation and aggregation
   • Reduced fibrinolysis (increased PAI-1)
   • Peak prothrombotic state at 24-72 hours postoperatively

4. Oxygen Supply-Demand Balance:

   • Critical coronary perfusion occurs during diastole
   • Coronary perfusion pressure = Diastolic BP - LVEDP
   • Tachycardia reduces diastolic time disproportionately
   • Anemia reduces oxygen-carrying capacity (DO₂ = CO × CaO₂)

5. Troponin Release Kinetics:

   • Myocyte injury releases cytoplasmic troponin (early peak, 3-6 hours)
   • Continued release from structurally bound troponin (sustained elevation, 7-14 days)
   • High-sensitivity assays detect smaller infarcts and earlier ischemia
   • Troponin I and T have similar diagnostic accuracy but different reference ranges

Critical Concept - The Fourth Universal Definition: The Fourth Universal Definition of MI (2018) classifies perioperative MI as occurring "during or within 30 days following surgery" and requires:

1. Detection of cardiac troponin elevation (> 99th percentile URL)
2. At least one of:
   • Symptoms of acute myocardial ischemia
   • New ischemic ECG changes
   • Development of pathological Q waves
   • Imaging evidence of new loss of viable myocardium or regional wall motion abnormality
   • Identification of coronary thrombus by angiography or autopsy

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Clinical Presentation

Symptoms

The cardinal feature of perioperative MI is its predominantly silent presentation, distinguishing it from spontaneous MI. Only 15-35% of patients report typical anginal symptoms. [4]

Typical Symptoms (when present):

• Chest pain or discomfort (only 15-35% of cases)
• Dyspnea (30-40%)
• Diaphoresis
• Nausea and vomiting

Atypical/Masked Presentations (common):

• Unexplained tachycardia
• Hypotension resistant to fluids
• New-onset arrhythmias (especially atrial fibrillation)
• Unexplained altered consciousness or delirium (especially elderly)
• Acute pulmonary edema
• Cardiac arrest

Reasons for Silent Presentation:

1. Residual anesthetic/analgesic effects masking pain
2. Competing surgical pain
3. Autonomic neuropathy (diabetes)
4. Altered sensorium (ICU sedation, delirium)
5. Predominantly Type 2 MI mechanism (gradual onset)

Signs

Cardiovascular Examination:

• Tachycardia (> 100 bpm) - present in 60-70%
• Hypotension (SBP less than 90 mmHg) - 30-40%
• Hypertension (HTN crisis) - 20-30%
• New cardiac murmur (papillary muscle dysfunction, VSD)
• Elevated jugular venous pressure
• S3 gallop (acute heart failure)
• Bilateral basal crackles (pulmonary edema)

Severity Indicators:

• Cardiogenic shock (SBP less than 90 mmHg, oliguria, altered consciousness)
• Acute pulmonary edema
• Mechanical complications (rare: less than 5%)
  • Acute mitral regurgitation (papillary muscle rupture)
  • Ventricular septal defect
  • Free wall rupture (usually fatal)

Clinical Pearl: High-Yield Examination Finding: In the postoperative setting, new-onset atrial fibrillation with rapid ventricular response should prompt immediate troponin measurement. Approximately 30-40% of postoperative AF cases are associated with myocardial injury or infarction, and AF itself increases myocardial oxygen demand.

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Differential Diagnosis

Critical to distinguish from other causes of troponin elevation and postoperative deterioration:

Most Critical Distinction: MINS vs PMI

MINS (Myocardial Injury after Noncardiac Surgery) is defined as troponin elevation > 99th percentile within 30 days of surgery, thought to be due to myocardial ischemia, but without fulfilling criteria for MI (i.e., lacks additional ischemic features). [5]

• MINS is more common (8-19% incidence with high-sensitivity troponin screening)
• MINS still carries significant mortality (3-5% at 30 days)
• MINS may benefit from cardiology consultation and medical optimization
• PMI requires troponin elevation PLUS ischemic evidence (symptoms, ECG, imaging)

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Investigations

First-Line Investigations

1. High-Sensitivity Cardiac Troponin (hs-cTn)

The cornerstone diagnostic test. Recommended measurement strategy: [14]

• Baseline: Preoperative measurement in high-risk patients (RCRI ≥1, age > 65, vascular surgery)
• Postoperative screening:
  • Day 1 (6-12 hours postoperatively)
  • Day 2 (24-48 hours postoperatively)
  • Day 3 if high-risk features or earlier elevation

Interpretation Thresholds:

Key Interpretation Challenges:

Exam Detail: Troponin Elevation in Context:

1. Magnitude of Elevation:

   • Minor elevation (1-3× URL): Common postoperatively, may represent Type 2 injury
   • Moderate elevation (3-10× URL): Significant myocardial injury, investigate for ischemia
   • Severe elevation (> 10× URL): High likelihood of Type 1 MI or large Type 2 infarct

2. Kinetics:

   • Acute MI: Rise and/or fall pattern (peak 12-24 hours, normalize by 7-14 days)
   • Chronic elevation: Stable elevated troponin (seen in CKD, heart failure)
   • Distinguish using serial measurements 3-6 hours apart (> 20% change suggests acute)

3. Assay-Specific Thresholds:

   • High-sensitivity TnT (Roche): 99th percentile = 14 ng/L
   • High-sensitivity TnI (Abbott): 99th percentile = 26 ng/L (men), 16 ng/L (women)
   • Always use local laboratory reference ranges

4. Confounding Factors:

   • CKD: Chronically elevated baseline, use dynamic changes
   • Heart failure: Elevated at baseline, look for acute rise
   • Age: 99th percentile increases with age
   • Sex: Women have lower 99th percentile values

2. 12-Lead Electrocardiogram (ECG)

Perform immediately when PMI suspected and serially (daily for 3 days in high-risk patients).

Diagnostic ECG Changes:

• STEMI pattern: ST elevation ≥1 mm in ≥2 contiguous leads (immediate catheterization)
• NSTEMI pattern:
  • New ST depression ≥0.5 mm
  • T wave inversion ≥1 mm in ≥2 contiguous leads
  • New Q waves (≥30 ms wide, ≥1 mm deep, or > 25% of QRS amplitude)
• Arrhythmias: New AF, VT, heart block

Limitations:

• ECG is normal in 30-40% of perioperative MI cases
• Pre-existing abnormalities (LBBB, LVH, old MI) complicate interpretation
• Non-specific changes common postoperatively (electrolyte shifts, hypothermia)

3. Transthoracic Echocardiography (TTE)

Indicated urgently when:

• Hemodynamic instability
• Suspected mechanical complication
• Significant troponin elevation with unclear etiology

Key Findings:

• Regional wall motion abnormalities (RWMA) in coronary territory
• Reduced left ventricular ejection fraction (LVEF)
• Mechanical complications (mitral regurgitation, VSD)
• Right ventricular dysfunction (suggests PE rather than PMI)

Second-Line Investigations

4. Coronary Angiography

Indications for Emergency Angiography (less than 2 hours):

• STEMI pattern on ECG
• Cardiogenic shock
• Electrical instability (VT/VF)

Indications for Urgent Angiography (less than 24 hours):

• High-risk NSTEMI (GRACE score > 140)
• Recurrent ischemia despite medical therapy
• Hemodynamic instability

Perioperative-Specific Considerations:

• Bleeding risk from dual antiplatelet therapy (DAPT)
• Recent surgery may preclude immediate PCI
• Multidisciplinary decision (cardiology, surgery, anesthesia)
• Radial access preferred to reduce bleeding risk

5. Cardiac Magnetic Resonance Imaging (CMR)

• Useful for distinguishing Type 1 vs Type 2 MI
• Identifies microvascular obstruction (poor prognosis)
• Late gadolinium enhancement confirms infarction
• Not suitable for acute/unstable patients

6. Additional Laboratory Tests

• Complete blood count: Anemia exacerbates ischemia (target Hb > 80-90 g/L in ACS)
• Renal function: Guides contrast use, medication dosing
• Electrolytes: Hypokalemia and hypomagnesemia increase arrhythmia risk
• Coagulation profile: Baseline before anticoagulation/antiplatelet therapy
• BNP/NT-proBNP: Elevated in heart failure, prognostic value
• Arterial blood gas: Assess oxygenation, acid-base status

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Diagnostic Criteria

Fourth Universal Definition of MI - Perioperative MI Criteria

Diagnosis requires:

1. Elevated cardiac troponin (> 99th percentile upper reference limit)

PLUS at least one of the following:

2. Symptoms of acute myocardial ischemia
3. New ischemic ECG changes:
   • New ST-segment or T-wave changes
   • New left bundle branch block
4. Development of pathological Q waves
5. Imaging evidence of new loss of viable myocardium or new regional wall motion abnormality in a pattern consistent with an ischemic etiology
6. Identification of a coronary thrombus by angiography or autopsy

Classification by Type:

• Type 1: Spontaneous MI due to atherosclerotic plaque rupture, ulceration, fissuring, erosion, or dissection
• Type 2: MI secondary to ischemic imbalance (most common perioperatively)
• Type 3: Cardiac death before biomarkers obtained
• Type 4a: PCI-related MI (troponin > 5× URL)
• Type 4b: Stent thrombosis
• Type 5: CABG-related MI (troponin > 10× URL + new Q waves or LBBB or angiographic occlusion or imaging loss of viable myocardium)

Exam Detail: Key Diagnostic Controversies:

1. Isolated Troponin Elevation (MINS):

   • Troponin elevation alone without ischemic features does NOT meet MI criteria
   • However, MINS still carries significant mortality and requires investigation
   • Some experts advocate treating MINS similarly to Type 2 MI

2. Troponin Threshold for Perioperative MI:

   • Fourth Universal Definition uses 99th percentile as threshold
   • Some propose higher thresholds for postoperative setting (e.g., 3× or 5× URL)
   • 2022 ESC Guidelines recommend using absolute troponin rise > 5× URL to distinguish MI from isolated injury in certain contexts

3. ECG Changes in the Context of Anesthesia:

   • General anesthesia and surgical stress can cause transient ECG changes
   • ST depression less than 1 mm may be non-specific
   • Serial ECGs crucial to identify evolving changes

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Risk Stratification

Revised Cardiac Risk Index (RCRI)

The most widely validated preoperative cardiac risk prediction tool. [12]

Six Independent Predictors (1 point each):

1. High-risk surgery (intraperitoneal, intrathoracic, suprainguinal vascular)
2. History of ischemic heart disease
3. History of congestive heart failure
4. History of cerebrovascular disease
5. Insulin therapy for diabetes mellitus
6. Preoperative serum creatinine > 2.0 mg/dL (> 177 μmol/L)

Risk of Major Cardiac Complications:

Limitations of RCRI:

• Developed before high-sensitivity troponin era
• Does not include functional capacity
• Poor discrimination in vascular surgery populations (C-statistic 0.67)

Enhanced Risk Prediction with Biomarkers

NT-proBNP:

• Preoperative NT-proBNP > 300 pg/mL independently predicts MACE
• Improves discrimination over RCRI alone (C-statistic 0.75 vs 0.67) [13]
• Cutoffs:
  • less than 100 pg/mL: Low risk
  • 100-300 pg/mL: Intermediate risk

  • 300 pg/mL: High risk

Functional Capacity:

• less than 4 METs: High-risk (unable to climb two flights of stairs or walk up a hill)
• 4-10 METs: Intermediate risk

• 10 METs: Low risk (can participate in strenuous sports)

Surgical Risk Stratification

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Management

Acute Management (Initial 0-24 Hours)

⚠️ Red Flag: Immediate Actions for Suspected PMI:

1. Call for help: Senior anesthesia, cardiology, ICU
2. ABCDE approach: Ensure airway, breathing, circulation stable
3. High-flow oxygen: Target SpO₂ 94-98% (if hypoxemic)
4. 12-lead ECG: Immediate, repeat if STEMI suspected
5. Troponin measurement: Urgent high-sensitivity troponin
6. IV access and monitoring: Continuous ECG, arterial line if unstable
7. Pain relief: Morphine 2-5 mg IV (reduces sympathetic drive)

STEMI in Perioperative Setting:

Indication for Primary PCI (if less than 12 hours from symptom onset):

• Persistent ST elevation
• Hemodynamic instability
• Electrical instability

Challenges:

• Recent surgery increases bleeding risk
• Antiplatelet/anticoagulation therapy contraindicated if active bleeding or very recent surgery (especially neurosurgery, ophthalmic, spinal)
• Multidisciplinary discussion required (surgeon, cardiologist, anesthesiologist)

Fibrinolysis:

• Generally contraindicated in perioperative period due to bleeding risk
• Absolute contraindications: Surgery within 3 weeks, active bleeding, intracranial pathology

NSTEMI/Type 2 MI in Perioperative Setting:

Medical Management

1. Antiplatelet Therapy

Evidence Debate: Aspirin:

Evidence:

• Aspirin reduces cardiovascular events in established CAD (secondary prevention)
• POISE-2 trial (2014): Aspirin initiated perioperatively did NOT reduce death or MI, but INCREASED major bleeding (RR 1.23) [15]
• However, aspirin continuation (not initiation) in patients on chronic therapy is recommended

Recommendations (2022 ESC Guidelines): [1]

• Continue aspirin perioperatively in patients on long-term therapy (unless very high bleeding risk surgery: intracranial, spinal canal, posterior eye chamber)
• Do NOT initiate aspirin de novo perioperatively for primary prevention
• Restart aspirin as soon as hemostasis achieved (ideally within 24-48 hours)

Beta-Blocker Controversy:

The POISE Trial (2008):

• Largest RCT of perioperative beta-blockade (8,351 patients)
• Metoprolol reduced MI rate (RR 0.73, p=0.0017)
• BUT increased stroke (RR 2.17, p=0.0053) and total mortality (RR 1.33, p=0.0317)
• Increased hypotension and bradycardia

Current Evidence-Based Approach: [16]

Key Principles:

• Never start high-dose beta-blocker on day of surgery
• Titrate to heart rate 60-70 bpm, avoid bradycardia
• Start at least 24-48 hours preoperatively (ideally 7-30 days)
• Monitor for hypotension and bradycardia

2. Anticoagulation

Unfractionated Heparin (UFH):

• Preferred in acute phase due to short half-life and reversibility
• Loading dose: 60-70 units/kg IV bolus (max 5000 units)
• Maintenance: 12-15 units/kg/hr, titrate to aPTT 1.5-2.5× control
• Can be stopped 4-6 hours before surgery, reversed with protamine

Low-Molecular-Weight Heparin (LMWH):

• Enoxaparin 1 mg/kg SC twice daily (treatment dose)
• Longer half-life, more difficult to reverse
• Hold ≥24 hours before neuraxial anesthesia or high-bleeding-risk procedures

Fondaparinux:

• Alternative if heparin-induced thrombocytopenia (HIT) suspected
• 2.5 mg SC daily
• Cannot be reversed (caution perioperatively)

3. Statin Therapy

• Continue statins perioperatively (associated with reduced cardiac events)
• High-intensity statin (Atorvastatin 80 mg or Rosuvastatin 40 mg) preferred
• Pleiotropic effects: Anti-inflammatory, plaque stabilization, endothelial function

4. ACE Inhibitor/ARB

• Controversy regarding continuation day of surgery
• Generally hold on morning of surgery to reduce intraoperative hypotension
• Restart postoperatively once hemodynamically stable

5. Blood Pressure Management

Target MAP ≥65 mmHg (some evidence suggests ≥70-75 mmHg in CAD patients)

Hypotension:

• Fluids if hypovolemic
• Vasopressors if fluid-unresponsive: Norepinephrine preferred (maintains coronary perfusion)
• Avoid prolonged hypotension (MAP less than 55 mmHg associated with myocardial injury)

Hypertension:

• Control severe hypertension (SBP > 180 mmHg) to reduce myocardial work
• IV labetalol, GTN, or nicardipine
• Avoid excessive reduction causing ischemia

6. Heart Rate Control

• Target HR 50-70 bpm in ACS
• Beta-blockers first-line (metoprolol, esmolol)
• Rate-limiting calcium channel blockers if beta-blocker contraindicated (diltiazem, verapamil)

7. Oxygen and Hemoglobin Optimization

• Oxygen: Maintain SpO₂ 94-98% (avoid hyperoxia and hypoxia)
• Anemia correction:
  • Transfusion threshold Hb less than 80 g/L in stable patients with CAD
  • Higher threshold (Hb less than 90-100 g/L) may be appropriate in acute MI or ongoing ischemia
  • Restrictive strategy generally preferred (avoid overtransfusion)

Interventional Management

Indications for Coronary Angiography:

Immediate (less than 2 hours):

• STEMI
• Cardiogenic shock
• Electrical instability (VT/VF)

Urgent (within 24 hours):

• High-risk NSTEMI (GRACE score > 140)
• Ongoing ischemia despite medical therapy
• Hemodynamic instability

Delayed/Elective:

• Stable post-MI with evidence of significant CAD on non-invasive testing

PCI Considerations in Perioperative Setting:

Challenges:

1. Bleeding risk: Recent surgery increases bleeding risk from DAPT and access site
2. Stent thrombosis risk: Premature discontinuation of DAPT
3. Timing of subsequent surgery: Need to delay surgery if stent placed

Perioperative Stent Management:

Radial vs Femoral Access:

• Radial access preferred perioperatively (lower bleeding risk)
• Femoral access if radial not feasible or patient unstable

Postoperative Care

1. ICU/HDU Monitoring

Indications for higher level of care:

• Hemodynamic instability requiring vasopressors/inotropes
• Respiratory failure
• Arrhythmias requiring monitoring
• Troponin > 10× URL
• Cardiogenic shock
• Post-PCI monitoring

Monitoring:

• Continuous ECG telemetry (≥48-72 hours)
• Invasive blood pressure monitoring if unstable
• Serial troponin (daily for 3 days)
• Serial ECGs (daily for 3 days)
• Echocardiography (assess LVEF, regional wall motion)

2. Cardiac Rehabilitation

• Risk factor modification
• Supervised exercise program
• Dietary counseling
• Psychological support
• Medication adherence

3. Secondary Prevention

Lifelong Medication (unless contraindicated):

• Aspirin 75-100 mg daily
• P2Y12 inhibitor (if stent placed): Clopidogrel 75 mg, Ticagrelor 90 mg BD, or Prasugrel 10 mg for 6-12 months
• High-intensity statin: Atorvastatin 80 mg or Rosuvastatin 20-40 mg
• ACE inhibitor (if LVEF less than 40% or anterior MI or diabetes or hypertension): Ramipril target 10 mg or Lisinopril 10 mg
• Beta-blocker (if LVEF less than 40% or heart failure): Bisoprolol, carvedilol, or metoprolol
• Mineralocorticoid receptor antagonist (if LVEF less than 40% and HF symptoms): Spironolactone 25-50 mg or eplerenone 25-50 mg

Risk Factor Modification:

• Smoking cessation (most important modifiable risk factor)
• Blood pressure target less than 130/80 mmHg
• LDL cholesterol target less than 1.4 mmol/L (less than 55 mg/dL)
• HbA1c target less than 7% in diabetes
• Weight loss if BMI > 25 kg/m²
• Regular physical activity (150 min/week moderate-intensity)

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Prevention Strategies

Preoperative Optimization

1. Cardiac Risk Assessment (All Patients ≥65 years or RCRI ≥1)

2022 ESC Guidelines Approach: [1]

Step 1: Assess Urgency

• Emergency surgery → Proceed to surgery (cannot delay for optimization)
• Urgent surgery (within days) → Limited time for assessment
• Elective surgery → Full risk stratification

Step 2: Assess Clinical Risk (RCRI)

• Low risk (0-1 factors) + good functional capacity (≥4 METs) → Proceed to surgery
• Intermediate-high risk (≥2 factors) OR poor functional capacity → Further assessment

Step 3: Biomarker Screening

• Measure NT-proBNP or BNP in intermediate-high risk patients
• NT-proBNP > 300 pg/mL or BNP > 92 pg/mL → High risk, consider further testing

Step 4: Functional Testing (if results will change management)

• Stress echocardiography or myocardial perfusion imaging
• Extensive inducible ischemia (> 3 segments) → Consider coronary angiography
• Limited ischemia → Optimize medical therapy and proceed

2. Troponin Surveillance

Indications for Postoperative Troponin Measurement: [14]

All patients with:

• Age ≥65 years
• RCRI ≥1
• BNP > 92 pg/mL or NT-proBNP > 300 pg/mL
• Vascular surgery
• Emergency surgery

Protocol:

• Baseline preoperative troponin (if possible)
• Day 1 postoperative (6-12 hours)
• Day 2 postoperative (24-48 hours)
• Day 3 if previous elevation or high suspicion

Reduces missed diagnoses by 60-70% (most PMI are silent)

3. Medication Management

Continue Perioperatively:

• Aspirin (unless very high bleeding risk surgery)
• Statins
• Beta-blockers (if already on therapy)
• ACE inhibitors/ARBs (debate; many hold on day of surgery)

Initiate if Not Already On:

• Statin therapy (at least 2 weeks preoperatively if possible)
• Beta-blocker (only if ≥3 RCRI factors, start ≥7 days preoperatively, titrate gradually)

4. Anemia Correction

• Preoperative Hb optimization (target ≥100 g/L if possible)
• Iron supplementation (IV iron if less than 2 weeks until surgery)
• Erythropoietin-stimulating agents in selected patients
• Treat underlying causes (B12/folate deficiency, GI bleeding)

Intraoperative Management

1. Hemodynamic Optimization

Avoid Hypotension:

• Maintain MAP ≥65 mmHg (some advocate ≥75 mmHg in high-risk patients)
• Episodes of MAP less than 55 mmHg strongly associated with MINS/PMI
• Use vasopressors (phenylephrine, norepinephrine) to maintain perfusion pressure

Heart Rate Control:

• Avoid tachycardia (HR > 100 bpm increases myocardial oxygen demand)
• Ensure adequate anesthetic depth and analgesia
• Beta-blockade if persistent tachycardia despite above measures

2. Anesthetic Technique

Regional vs General Anesthesia:

• No definitive evidence that regional anesthesia reduces cardiac events
• Regional techniques may reduce pain and stress response
• Choose technique based on surgical requirements and patient factors

Goal-Directed Fluid Therapy:

• Avoid both hypovolemia (hypotension) and hypervolemia (pulmonary edema)
• Stroke volume optimization using cardiac output monitoring
• Balanced crystalloids preferred over 0.9% saline

3. Temperature Management

• Maintain normothermia (36-37°C)
• Hypothermia increases oxygen consumption (shivering), coagulopathy
• Active warming devices (forced-air warmers)

4. Transfusion Strategy

• Restrictive transfusion threshold (Hb less than 70-80 g/L in stable patients)
• Liberal threshold (Hb less than 90 g/L) may be appropriate in acute ischemia
• Avoid unnecessary transfusion (increases risk of ARDS, infection, immunomodulation)

Postoperative Management

1. Enhanced Recovery Protocols

• Early mobilization (reduces VTE, improves cardiovascular function)
• Multimodal analgesia (reduces opioid requirements, stress response)
• Early oral intake
• Minimize drains and catheters

2. Pain Management

• Adequate analgesia reduces sympathetic surge (tachycardia, hypertension)
• Multimodal approach: Regional techniques, NSAIDs (caution in renal dysfunction), paracetamol, opioids
• Regional analgesia (epidural, paravertebral blocks) for major surgery

3. Glucose Control

• Hyperglycemia (> 10 mmol/L) associated with worse outcomes in MI
• Target glucose 6-10 mmol/L
• Avoid hypoglycemia (less than 4 mmol/L)

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Complications

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Prognosis

Short-Term Outcomes

30-Day Mortality:

• Perioperative MI: 10-15% [6]
• MINS (myocardial injury without MI): 3-5% [5]
• Non-surgical acute MI: 5-10%
• Perioperative MI carries similar mortality to non-surgical MI

Factors Associated with Higher Mortality:

• STEMI vs NSTEMI (15-20% vs 8-12%)
• Cardiogenic shock (50-70% mortality)
• Anterior MI (worse than inferior)
• Age > 75 years
• Reduced LVEF (less than 40%)
• Chronic kidney disease
• Diabetes mellitus
• Emergency surgery

Long-Term Outcomes

1-Year Mortality:

• Perioperative MI: 25-30% [11]
• Significantly higher than matched controls without PMI

Cardiovascular Events:

• Recurrent MI: 8-12% at 1 year
• Heart failure: 15-20% develop symptomatic heart failure
• Stroke: 3-5% at 1 year

Functional Status:

• 30-40% report reduced quality of life
• 20-30% unable to return to previous activity level
• Cardiac rehabilitation improves functional outcomes

Prognostic Factors

Poor Prognostic Indicators:

• Peak troponin > 10× URL
• LVEF less than 40%
• Anterior territory infarction
• Multivessel disease
• Incomplete revascularization
• Ongoing ischemia
• Renal dysfunction (CrCl less than 60 mL/min)
• Age > 75 years
• Diabetes mellitus
• Previous MI

Good Prognostic Indicators:

• Small Type 2 MI with correctable precipitant
• Preserved LVEF (> 50%)
• Single-vessel disease successfully revascularized
• Compliance with secondary prevention medications
• Cardiac rehabilitation participation

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Key Guidelines

1. 2022 ESC Guidelines on Cardiovascular Assessment and Management of Patients Undergoing Non-cardiac Surgery [1]

Key Recommendations:

• Use RCRI for preoperative risk stratification (Class I)
• Measure NT-proBNP or BNP in intermediate-high risk patients (Class IIa)
• Continue aspirin in patients on chronic therapy unless very high bleeding risk (Class IIa)
• Do NOT initiate aspirin de novo perioperatively for primary prevention (Class III)
• Continue statins perioperatively (Class I)
• Continue beta-blockers in patients already on therapy (Class I)
• Consider beta-blockers in high-risk patients (≥3 RCRI) started ≥1 day before surgery (Class IIa)
• Postoperative troponin surveillance in patients age ≥65 or RCRI ≥1 (Class IIa)

2. 2014 ACC/AHA Guideline on Perioperative Cardiovascular Evaluation and Management of Patients Undergoing Noncardiac Surgery [17]

Key Recommendations:

• Perioperative beta-blockade should be continued in patients on chronic therapy (Class I)
• Beta-blockers titrated to heart rate and blood pressure may be reasonable in vascular surgery patients (Class IIb)
• Routine beta-blocker initiation on day of surgery is potentially harmful (Class III Harm)
• Statins should be continued in patients on chronic therapy (Class I)
• Statin initiation is reasonable in vascular surgery patients (Class IIa)

3. Fourth Universal Definition of Myocardial Infarction (2018) [3]

• Defines diagnostic criteria for perioperative MI
• Distinguishes Type 1 (plaque rupture) from Type 2 (supply-demand mismatch)
• Requires troponin elevation + ischemic features

4. Canadian Cardiovascular Society Guidelines on Perioperative Cardiac Risk Assessment and Management (2017)

• Recommends BNP/NT-proBNP measurement in intermediate-high risk patients
• Advocates for troponin surveillance postoperatively
• Emphasizes multidisciplinary care

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Exam-Focused Sections

Common Viva Questions

Viva Point: 1. "What is perioperative myocardial infarction and how common is it?"

Model Answer: "Perioperative myocardial infarction is acute myocardial injury occurring within 30 days of surgery, characterized by elevated cardiac troponin levels above the 99th percentile with evidence of acute myocardial ischemia. It occurs in approximately 1-5% of patients undergoing noncardiac surgery, with higher rates in vascular surgery populations.

The incidence has increased with the advent of high-sensitivity troponin assays and systematic surveillance protocols. Importantly, the majority of cases—65-84%—are clinically silent, detected only through troponin screening. The 30-day mortality is 10-15%, similar to non-surgical acute MI, making it a critical perioperative complication."

2. "How does perioperative MI differ from MINS?"

Model Answer: "MINS, or Myocardial Injury after Noncardiac Surgery, represents troponin elevation above the 99th percentile thought to be due to myocardial ischemia but WITHOUT additional ischemic features required for MI diagnosis.

Perioperative MI requires troponin elevation PLUS at least one of: ischemic symptoms, new ECG changes, pathological Q waves, imaging evidence of new myocardial loss, or coronary thrombus on angiography, as defined by the Fourth Universal Definition.

MINS is more common than PMI—affecting 8-19% vs 1-5% of patients—but carries lower mortality: 3-5% vs 10-15% at 30 days. However, both require cardiology assessment and medical optimization, as MINS still independently predicts adverse outcomes."

3. "Describe the pathophysiology of Type 2 MI in the perioperative setting."

Model Answer: "Type 2 myocardial infarction results from myocardial oxygen supply-demand mismatch rather than acute coronary thrombosis. It accounts for 60-70% of perioperative MIs.

The pathophysiology involves:

Increased oxygen demand: Surgical stress activates the sympathetic nervous system and HPA axis, increasing catecholamines. This causes tachycardia and hypertension, raising the heart rate-blood pressure product and myocardial work.

Decreased oxygen supply: Intraoperative hypotension—particularly MAP below 55-60 mmHg—reduces coronary perfusion pressure, which equals diastolic BP minus left ventricular end-diastolic pressure. Anemia reduces oxygen-carrying capacity. Tachycardia shortens diastolic time, further compromising coronary flow.

Additional factors: Systemic inflammation from surgery promotes endothelial dysfunction. Hypercoagulability from increased fibrinogen and platelet activation may cause microvascular thrombosis. Hypoxemia and increased metabolic demands from pain, shivering, or infection exacerbate the imbalance.

The result is myocardial ischemia and necrosis despite no acute plaque rupture."

4. "Walk me through your interpretation of an elevated troponin on postoperative day 1."

Model Answer: "I would approach this systematically:

First, establish the clinical context:

• Is the patient symptomatic? Chest pain, dyspnea, hemodynamic instability?
• Review vital signs: tachycardia, hypotension, hypoxemia?
• Any intraoperative complications? Hypotension, blood loss, arrhythmias?

Second, characterize the troponin elevation:

• Magnitude: Minor (1-3× URL) vs moderate (3-10×) vs severe (> 10× URL)
• Kinetics: Compare to baseline preoperative troponin if available
• Assay type: High-sensitivity troponin I or T, with local laboratory reference ranges

Third, investigate for ischemic features:

• Urgent 12-lead ECG: Look for ST elevation, ST depression, T wave inversion, new Q waves
• Review serial ECGs: Any evolving changes?
• Symptoms: Even atypical symptoms like unexplained tachycardia or delirium
• Imaging: Echocardiography to assess regional wall motion abnormalities

Fourth, determine diagnosis:

• If ischemic features present → Perioperative MI: Urgent cardiology consultation, consider angiography if high-risk
• If isolated troponin elevation without ischemic features → MINS: Still requires cardiology assessment, medical optimization, investigate precipitants
• If chronic stable elevation (e.g., CKD patient) → Ensure no acute rise (> 20% change suggests acute event)

Fifth, manage appropriately:

• Antiplatelet therapy if no contraindication
• Optimize hemodynamics, correct anemia, ensure adequate oxygenation
• Statin therapy
• Serial troponin and ECG monitoring
• Multidisciplinary discussion regarding further intervention and timing of any subsequent surgery."

5. "What is your approach to beta-blocker management in the perioperative period?"

Model Answer: "My approach follows the evidence from the POISE trial and current guidelines:

For patients ALREADY on beta-blockers:

• Continue perioperatively (Class I recommendation)
• Withholding beta-blockers increases risk of rebound tachycardia, hypertension, and ischemia
• Ensure the beta-blocker is administered on the morning of surgery

For patients NOT on beta-blockers:

• Low-intermediate risk (0-2 RCRI factors): Do NOT start beta-blocker (Class III—may cause harm due to hypotension and stroke risk)
• High cardiac risk (≥3 RCRI factors): Consider beta-blocker if started ≥1 day before surgery (ideally 7-30 days), titrated gradually to heart rate 60-70 bpm and systolic BP > 100 mmHg (Class IIa)
• NEVER start high-dose beta-blocker on the day of surgery — this was the error in POISE that led to excess stroke and mortality

Intraoperative/postoperative management:

• Monitor for hypotension (SBP less than 100 mmHg) and bradycardia (HR less than 60 bpm)
• These adverse effects are harmful and negate the benefits of beta-blockade
• Adjust or hold beta-blocker if hemodynamically unstable

The key lesson from POISE is that beta-blockers reduce MI but increase stroke and death when started acutely without titration, particularly when causing hypotension."

6. "Should aspirin be continued perioperatively?"

Model Answer: "This depends on whether the patient is already on aspirin chronically or if we are considering initiating it:

Patients on chronic aspirin therapy (secondary prevention):

• Continue aspirin through the perioperative period in most cases (Class IIa recommendation)

• The cardiovascular benefit generally outweighs bleeding risk

• Exceptions—consider withholding in very high bleeding risk surgery:

  • Intracranial neurosurgery
  • Spinal canal surgery
  • Posterior eye chamber surgery
  • Perhaps major cancer surgery where bleeding is life-threatening

• If aspirin is withheld, restart as soon as hemostasis is achieved, ideally within 24-48 hours

De novo aspirin initiation perioperatively:

• Do NOT initiate aspirin for primary prevention in the perioperative period (Class III recommendation)
• Based on POISE-2 trial: Aspirin initiated perioperatively did not reduce death or MI but increased major bleeding by 23%

Dual antiplatelet therapy (DAPT) after coronary stenting:

• This is a special situation requiring multidisciplinary discussion
• Ideally, delay elective surgery until minimum DAPT duration completed (4-6 weeks for BMS, 6-12 months for DES)
• If surgery cannot be delayed, continue aspirin if at all possible
• The risk of stent thrombosis may outweigh surgical bleeding risk in many cases

Bottom line: Continue chronic aspirin, do not initiate de novo, individualize decisions for high bleeding risk surgery."

Common Mistakes (Exam Failures)

❌ Failure Points:

1. Missing the diagnosis:

   • Not recognizing that most perioperative MIs are silent
   • Failing to measure troponin in high-risk patients
   • Dismissing troponin elevation as "expected postoperatively"

2. Incorrect definition:

   • Confusing MINS with perioperative MI
   • Not knowing Fourth Universal Definition criteria
   • Stating that any troponin elevation equals MI (ignores requirement for ischemic features)

3. Beta-blocker errors:

   • Starting high-dose beta-blocker on day of surgery
   • Not knowing POISE trial results
   • Blanket statement "all high-risk patients should get beta-blockers" (nuance required)

4. Aspirin errors:

   • Withholding aspirin unnecessarily in patients on chronic therapy
   • Initiating aspirin perioperatively for primary prevention
   • Not knowing POISE-2 trial

5. Anticoagulation in recent surgery:

   • Immediately fully anticoagulating and dual antiplatelet therapy in a patient who just had major surgery without considering bleeding risk
   • Not having multidisciplinary discussion

6. Revascularization timing:

   • Immediately recommending PCI without considering bleeding risk and multidisciplinary input
   • Not understanding that many Type 2 MIs can be managed medically by optimizing hemodynamics

7. Troponin interpretation:

   • Not recognizing that chronic kidney disease causes chronically elevated baseline troponin
   • Ignoring troponin kinetics (rise/fall pattern indicates acute event)
   • Using wrong reference ranges

8. Risk stratification:

   • Not knowing the 6 components of RCRI
   • Not knowing the risk percentages associated with each RCRI score
   • Ordering expensive unnecessary tests (e.g., stress testing in low-risk patient)

Model Answers for Common Scenarios

Scenario 1: "A 72-year-old man with diabetes and previous MI undergoes emergency laparotomy for perforated diverticulitis. On day 1 postoperatively, he has no chest pain but is noted to be tachycardic at 110 bpm with BP 105/70. Troponin is 350 ng/L (upper reference limit 14 ng/L). How do you manage him?"

Model Answer:

"This patient has significant postoperative troponin elevation—25 times the upper reference limit—in the context of high cardiac risk (age 72, diabetes, previous MI). Although he has no chest pain, the tachycardia and troponin elevation are concerning for perioperative myocardial injury or infarction.

Immediate assessment:

1. ABCDE approach: Ensure airway, breathing, circulation stable
2. Urgent 12-lead ECG: Look for ST elevation, ST depression, T wave inversion, or new Q waves indicating ischemia
3. Review observations: Is there hypotension, hypoxemia, fever suggesting precipitant?
4. Assess volume status: Is he hypovolemic (tachycardia, low BP) from surgical losses?
5. Check hemoglobin: Anemia would exacerbate myocardial ischemia

Investigations:

• Serial troponin (repeat in 3-6 hours to assess kinetics—rising suggests acute event)
• Full blood count (anemia?)
• Renal function and electrolytes (K, Mg)
• Arterial blood gas if concerns about oxygenation
• Transthoracic echocardiography to assess LVEF and regional wall motion abnormalities

Immediate management:

• Oxygen if hypoxemic (target SpO₂ 94-98%)
• Fluid resuscitation if hypovolemic (likely given recent laparotomy)
• Blood transfusion if Hb less than 80 g/L (possibly higher threshold less than 90 g/L given ischemia)
• Rate control: Beta-blocker (e.g., IV metoprolol 2.5-5 mg) to reduce HR to 60-70 bpm IF hemodynamically stable
• Pain control: Ensure adequate analgesia to reduce sympathetic drive

Definitive management:

• Urgent cardiology consultation: Determine if this is PMI (if ECG/echo show ischemic features) or MINS
• Antiplatelet therapy: Aspirin 75-300 mg (if no active bleeding from surgery)
• Consider anticoagulation: Weigh risk vs benefit given recent laparotomy—may defer if high bleeding risk
• Statin: High-intensity (atorvastatin 80 mg)
• Optimize hemodynamics: Avoid hypotension and tachycardia

Disposition:

• ICU/HDU for continuous monitoring
• Multidisciplinary discussion (cardiology, surgery, anesthesia) regarding need for coronary angiography vs medical management

Likely diagnosis: This is either Type 2 MI from perioperative stress (tachycardia, possible hypotension, anemia) or Type 1 MI. The ECG and echo will distinguish. Management focuses on optimizing oxygen delivery (fluids, transfusion, oxygen), reducing oxygen demand (rate control, pain control), and cardiology-guided therapy."

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Scenario 2: "You are asked to perform preoperative assessment on a 68-year-old woman scheduled for elective total knee replacement. She has hypertension treated with ramipril and type 2 diabetes on metformin. She can walk 100 meters on flat ground before stopping due to knee pain. What is your cardiac risk assessment?"

Model Answer:

"I need to systematically assess her perioperative cardiac risk.

Step 1: Assess surgical urgency and type

• Elective surgery → Adequate time for full assessment
• Orthopedic surgery (total knee replacement) → Intermediate-risk surgery (1-5% cardiac event rate)

Step 2: Calculate RCRI score The six factors are: high-risk surgery, ischemic heart disease, heart failure, cerebrovascular disease, insulin-dependent diabetes, and creatinine > 177 μmol/L.

• High-risk surgery: No (orthopedic is intermediate)
• Ischemic heart disease: Not mentioned
• Heart failure: Not mentioned
• Cerebrovascular disease: Not mentioned
• Insulin-dependent diabetes: No (she is on metformin, not insulin)
• Creatinine > 177 μmol/L: Unknown—need to check

Provisional RCRI score: 0-1 (depending on renal function)

Step 3: Assess functional capacity

• She can only walk 100 meters on flat ground due to knee pain
• Functional capacity unclear—knee pain limits assessment
• Cannot reliably assess METs (would need to ask about other activities like climbing stairs, but knee pain confounds this)

Step 4: Risk stratification

• Age 68, intermediate-risk surgery, RCRI 0-1, functional capacity uncertain
• Overall: Low-intermediate cardiac risk

My approach:

1. Basic investigations:

   • ECG (baseline)
   • Full blood count, renal function, electrolytes, HbA1c
   • Consider NT-proBNP: In a patient age > 65 with diabetes, this would help refine risk. If NT-proBNP > 300 pg/mL, higher risk.

2. Medication optimization:

   • Continue ramipril and metformin (hold ramipril morning of surgery, restart postoperatively)
   • If not already on statin, consider initiating (Class IIa recommendation for vascular surgery; reasonable in diabetic patient)
   • Do NOT initiate beta-blocker (low-intermediate risk)

3. Functional testing: Not indicated—unlikely to change management for intermediate-risk surgery unless NT-proBNP very elevated

4. Perioperative plan:

   • Proceed to surgery
   • Postoperative troponin surveillance (age > 65 years is indication): Day 1 and Day 2 postop
   • Continuous ECG monitoring for 24-48 hours
   • Optimize analgesia and early mobilization (enhanced recovery protocol)

**If NT-proBNP turns out to be very elevated (e.g., > 1000 pg/mL) or renal function is poor, I would consider cardiology consultation and possibly functional testing (stress echo or myocardial perfusion) if results would change management—for instance, if severe inducible ischemia might prompt coronary angiography prior to surgery.

Bottom line: Low-intermediate risk patient, can proceed to surgery with standard monitoring and postoperative troponin surveillance."

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References

1. Halvorsen S, Mehilli J, Cassese S, et al. 2022 ESC Guidelines on cardiovascular assessment and management of patients undergoing non-cardiac surgery. Eur Heart J. 2022;43(39):3826-3924. doi:10.1093/eurheartj/ehac270

2. Smilowitz NR, Gupta N, Ramakrishna H, et al. Perioperative major adverse cardiovascular and cerebrovascular events associated with noncardiac surgery. JAMA Cardiol. 2017;2(2):181-187. doi:10.1001/jamacardio.2016.4792

3. Thygesen K, Alpert JS, Jaffe AS, et al. Fourth universal definition of myocardial infarction (2018). Eur Heart J. 2019;40(3):237-269. doi:10.1093/eurheartj/ehy462

4. Devereaux PJ, Xavier D, Pogue J, et al. Characteristics and short-term prognosis of perioperative myocardial infarction in patients undergoing noncardiac surgery: a cohort study. Ann Intern Med. 2011;154(8):523-528. doi:10.7326/0003-4819-154-8-201104190-00003

5. Botto F, Alonso-Coello P, Chan MT, et al. Myocardial injury after noncardiac surgery: a large, international, prospective cohort study establishing diagnostic criteria, characteristics, predictors, and 30-day outcomes. Anesthesiology. 2014;120(3):564-578. doi:10.1097/ALN.0000000000000113

6. Devereaux PJ, Biccard BM, Sigamani A, et al. Association of postoperative high-sensitivity troponin levels with myocardial injury and 30-day mortality among patients undergoing noncardiac surgery. JAMA. 2017;317(16):1642-1651. doi:10.1001/jama.2017.4360

7. Smilowitz NR, Berger JS. Perioperative cardiovascular risk assessment and management for noncardiac surgery: a review. JAMA. 2020;324(3):279-290. doi:10.1001/jama.2020.7840

8. Gualandro DM, Campos CA, Calderaro D, et al. Incidence and outcomes of perioperative myocardial infarction/injury diagnosed by high-sensitivity cardiac troponin I. Clin Res Cardiol. 2021;110(9):1405-1414. doi:10.1007/s00392-021-01827-w

9. Flu WJ, van Kuijk JP, Hoeks SE, et al. Prognostic implications of asymptomatic cardiac troponin T elevation in vascular surgery patients. Eur J Vasc Endovasc Surg. 2010;40(6):738-743. doi:10.1016/j.ejvs.2010.08.008

10. Puelacher C, Lurati Buse G, Seeberger D, et al. Perioperative myocardial injury after noncardiac surgery: incidence, mortality, and characterization. Circulation. 2018;137(12):1221-1232. doi:10.1161/CIRCULATIONAHA.117.030114

11. Noordzij PG, van Geffen O, Dijkstra IM, et al. High-sensitive cardiac troponin T measurements in prediction of non-cardiac complications after major abdominal surgery. Br J Anaesth. 2015;114(6):909-918. doi:10.1093/bja/aev027

12. Lee TH, Marcantonio ER, Mangione CM, et al. Derivation and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery. Circulation. 1999;100(10):1043-1049. doi:10.1161/01.cir.100.10.1043

13. Vernooij LM, van Klei WA, Moons KG, et al. The comparative and added prognostic value of biomarkers to the Revised Cardiac Risk Index for preoperative prediction of major adverse cardiac events and all-cause mortality in patients who undergo noncardiac surgery. Cochrane Database Syst Rev. 2021;12(12):CD013139. doi:10.1002/14651858.CD013139.pub2

14. Sessler DI, Khanna AK. Perioperative troponin screening. Anesth Analg. 2016;123(2):359-369. doi:10.1213/ANE.0000000000001450

15. Devereaux PJ, Mrkobrada M, Sessler DI, et al. Aspirin in patients undergoing noncardiac surgery. N Engl J Med. 2014;370(16):1494-1503. doi:10.1056/NEJMoa1401105

16. Wijeysundera DN, Duncan D, Nkonde-Price C, et al. Perioperative beta blockade in noncardiac surgery: a systematic review for the 2014 ACC/AHA guideline on perioperative cardiovascular evaluation and management of patients undergoing noncardiac surgery. J Am Coll Cardiol. 2014;64(22):2406-2425. doi:10.1016/j.jacc.2014.07.939

17. Fleisher LA, Fleischmann KE, Auerbach AD, et al. 2014 ACC/AHA guideline on perioperative cardiovascular evaluation and management of patients undergoing noncardiac surgery. J Am Coll Cardiol. 2014;64(22):e77-e137. doi:10.1016/j.jacc.2014.07.944

18. Bollen Pinto B, Silvestre J, Pereira Morais C, et al. Pathophysiological mechanisms underlying increased circulating cardiac troponin in noncardiac surgery: a narrative review. Br J Anaesth. 2024;132(4):681-692. doi:10.1016/j.bja.2023.12.017

19. Szczeklik W, Wajda J, Ostrowska M, et al. Myocardial injury after noncardiac surgery—an update. Curr Opin Anaesthesiol. 2021;34(3):317-325. doi:10.1097/ACO.0000000000000981

20. Bello C, Patel K, Smilowitz NR. Perioperative strategies to reduce risk of myocardial injury after non-cardiac surgery (MINS): A narrative review. J Clin Anesth. 2023;88:111106. doi:10.1016/j.jclinane.2023.111106

21. Oprea AD, Lombard FW. Perioperative personalized β-blocker management in the perioperative setting. J Anesth. 2020;34(1):100-111. doi:10.1007/s00540-019-02691-9

22. Halvorsen S, Navarese EP, Cassese S, et al. Continue or discontinue aspirin before non-cardiac surgery? Eur Heart J. 2023;44(26):2381-2395. doi:10.1093/eurheartj/ehad246

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Summary

Perioperative myocardial infarction represents a critical cardiovascular complication affecting 1-5% of noncardiac surgical patients, with 30-day mortality of 10-15%. Most cases (65-84%) are clinically silent, emphasizing the importance of systematic troponin surveillance in high-risk patients (age ≥65 years, RCRI ≥1, vascular surgery). The Fourth Universal Definition requires troponin elevation above the 99th percentile plus ischemic features (symptoms, ECG changes, imaging abnormalities), distinguishing PMI from the broader category of MINS.

Pathophysiology predominantly involves Type 2 MI (supply-demand mismatch) rather than Type 1 MI (plaque rupture), driven by hemodynamic stress, anemia, inflammation, and hypercoagulability. Diagnosis relies on high-sensitivity troponin measurement with attention to magnitude, kinetics, and ischemic context. Management requires a multidisciplinary approach balancing cardiovascular benefit against surgical bleeding risk, with continuation of aspirin and statins, optimization of hemodynamics, and selective use of coronary angiography.

Prevention centers on preoperative risk stratification using RCRI and biomarkers (NT-proBNP), perioperative medication optimization (continue chronic beta-blockers and statins, continue aspirin in most cases, avoid initiating beta-blockers acutely), intraoperative hemodynamic management (avoid hypotension MAP less than 65 mmHg), and postoperative troponin surveillance. Evidence-based controversies include the role of perioperative beta-blockers (POISE trial showing reduced MI but increased stroke/death) and aspirin continuation (POISE-2 showing increased bleeding with de novo initiation but benefit with continuation in chronic users). Long-term prognosis remains poor with 25-30% 1-year mortality, mandating aggressive secondary prevention and cardiac rehabilitation.