Predicting, Protecting, and Preventing MI in Non-Cardiac Surgery
Risk Prediction: Use the Revised Cardiac Risk Index (RCRI) as Your Primary Tool
The RCRI (Lee Index) remains the foundation for predicting perioperative MI, incorporating six clinical variables: type of surgery, history of ischemic heart disease, history of heart failure, history of cerebrovascular disease, insulin-dependent diabetes, and preoperative creatinine >2 mg/dL. 1, 2
Risk Stratification Algorithm
Step 1: Identify Active Cardiac Conditions Requiring Immediate Evaluation
- Unstable coronary syndromes (unstable or severe angina) 1, 2
- Recent MI (within 30 days) or acute MI (within 7 days) 1, 2
- Decompensated heart failure 1, 2
- Significant arrhythmias (high-grade AV block, symptomatic arrhythmias, uncontrolled atrial fibrillation) 1
- Severe valvular disease 1, 2
If any active condition is present, postpone elective surgery until evaluated and stabilized. 1, 2
Step 2: Assess Functional Capacity in METs
- ≥10 METs (strenuous sports, running): Proceed to surgery without further testing regardless of risk factors 2, 3
- 4-10 METs (climbing stairs, walking briskly, playing golf): Proceed to surgery 1, 2
- <4 METs (cannot walk 2 blocks or climb 1 flight of stairs): Proceed to Step 3 1, 2
Step 3: Calculate RCRI Score (0-6 points)
- High-risk surgery (vascular, major emergency, prolonged procedures with large fluid shifts): 1 point 1
- History of ischemic heart disease: 1 point 1, 2
- History of heart failure: 1 point 1, 2
- History of cerebrovascular disease: 1 point 1, 2
- Insulin-dependent diabetes: 1 point 1, 2
- Creatinine >2 mg/dL: 1 point 1, 2
Risk stratification by RCRI score:
- 0 factors: 0.4-0.6% cardiac event rate 2, 4
- 1-2 factors: 1-5% cardiac event rate 2, 4
- ≥3 factors: 11% or higher cardiac event rate 2, 4
Step 4: Stratify Surgical Risk
- Low-risk surgery (<1% cardiac event rate): Proceed without further testing 1, 2
- Intermediate-risk surgery (1-5%): Consider testing only if ≥3 RCRI factors and poor functional capacity 1, 2
- High-risk surgery (>5%): Consider noninvasive testing if ≥3 RCRI factors, poor functional capacity, and results will change management 1, 2
Enhanced Prediction with Preoperative Troponin
Adding preoperative high-sensitivity troponin significantly improves prediction accuracy (AUC 0.79 vs 0.73 for clinical variables alone), particularly in high-risk patients. 5 This represents the most recent evidence for risk prediction enhancement, though it is not yet incorporated into standard guidelines.
Protection: Perioperative Medical Management
Beta-Blockers: Continue, Don't Initiate
Continue beta-blockers in patients already taking them—withdrawal increases 1-year mortality with a hazard ratio of 2.7 (50% mortality with discontinuation vs 1.5% with continuation). 3
Do not routinely initiate beta-blockers in beta-blocker-naïve patients, particularly within 1 day of surgery. 1, 3 The evidence shows harm from acute initiation, contrasting with benefit from chronic therapy.
Statins: Start Early, Continue Always
Initiate statins in statin-naïve patients with atherosclerotic cardiovascular disease or elevated ASCVD risk who are undergoing vascular or elevated-risk surgery, ideally starting 30 days preoperatively. 3
Statins reduce major adverse cardiac events by approximately 60% in vascular surgery patients (from 26% to 8% with atorvastatin 20 mg daily). 3 This represents one of the most powerful protective interventions available.
Continue statins perioperatively in all patients already taking them. 3
Aspirin: Continue for Secondary Prevention
Continue aspirin perioperatively for secondary prevention unless bleeding risk is extremely high (such as intracranial surgery). 3 The thrombotic risk of perioperative MI generally outweighs bleeding risk in most surgical contexts.
Coronary Revascularization: Only for Standard Indications
Do not perform routine prophylactic coronary revascularization before noncardiac surgery in patients with stable coronary artery disease. 3, 6 Multiple trials have shown no benefit and potential harm from this strategy.
Revascularize only for standard indications independent of planned surgery: significant left main stenosis, 3-vessel disease, 2-vessel disease with proximal LAD involvement, high-risk unstable angina, or non-ST-elevation MI. 3
Prevention Through Surveillance: Detect MI Early
High-Risk Patients Require Systematic Monitoring
For high-risk patients (known CAD, heart failure, cerebrovascular disease, diabetes, renal insufficiency, or undergoing vascular/major surgery), obtain baseline ECG, repeat immediately post-surgery and daily for 2 days, plus measure troponin at baseline and 48-72 hours post-surgery. 1, 7
Up to 50% of perioperative MIs are clinically silent—systematic surveillance is essential. 6
Diagnostic Criteria for Perioperative MI
Myocardial Injury After Noncardiac Surgery (MINS) is defined as any troponin elevation >99th percentile of presumed ischemic origin within 30 days after surgery. 2, 7
MINS carries approximately 10% 30-day mortality, with risk proportional to peak troponin concentration. 2
Even isolated troponin elevation without ECG changes predicts increased long-term mortality. 7
Low-Risk Patients: No Routine Surveillance
Do not perform routine postoperative troponin or ECG screening in asymptomatic patients undergoing low-risk surgery. 3, 7 The yield is too low to justify systematic testing.
Management of Perioperative MI
Immediate Medical Therapy
Initiate aspirin, beta-blockers, ACE inhibitors, and high-intensity statin therapy immediately for all patients with perioperative MI. 1, 3
Start aspirin immediately and continue indefinitely unless bleeding risk is prohibitive. 3
Reperfusion Strategy: Individualized Decision
For perioperative STEMI from acute thrombotic occlusion, consider immediate coronary angiography and PCI, carefully balancing bleeding versus thrombotic risks. 1, 3
Fibrinolytic therapy is generally contraindicated due to high bleeding risk at the surgical site. 1 Recent surgery has been an exclusion criterion in all fibrinolytic trials.
For Type 2 MI (supply-demand mismatch), focus on correcting underlying causes: hypotension, tachycardia, anemia, or hypertension. 3 These patients do not benefit from emergent revascularization.
Post-MI Evaluation
Evaluate left ventricular function before hospital discharge in all patients who sustain perioperative MI. 1, 3 This guides long-term therapy and prognosis.
Perioperative MI carries 40-70% mortality and high risk for future cardiac events—aggressive secondary prevention is mandatory. 1, 7
Common Pitfalls to Avoid
Do not rely on clinical symptoms alone—50% of perioperative MIs are silent. 6 Systematic surveillance with ECG and troponin is required in high-risk patients.
Do not initiate beta-blockers acutely before surgery in beta-blocker-naïve patients. 1, 3 This increases mortality rather than reducing it.
Do not perform routine preoperative stress testing in patients with good functional capacity (≥4 METs). 2 Functional capacity assessment is more predictive and less costly.
Do not pursue prophylactic coronary revascularization before noncardiac surgery. 3, 6 This strategy has been definitively shown not to improve outcomes.