Prediction of Myocardial Infarction in Patients Undergoing Non-Cardiac Surgery

Risk Stratification Framework

• The American Heart Association/American College of Cardiology guidelines recommend a stepwise approach using the Revised Cardiac Risk Index (RCRI) as the foundation for predicting perioperative myocardial infarction, incorporating clinical risk factors, functional capacity assessment, and surgical risk stratification 1, 2
• Active cardiac conditions requiring immediate evaluation include unstable coronary syndromes, recent myocardial infarction, acute myocardial infarction, decompensated heart failure, significant arrhythmias, and severe valvular disease 1, 2, 3

Clinical Risk Factors

• The guidelines identify five key clinical risk factors that predict perioperative myocardial infarction: history of ischemic heart disease, history of compensated or prior heart failure, history of cerebrovascular disease, diabetes mellitus, and renal insufficiency 1, 2
• The presence of 3 or more clinical risk factors substantially increases perioperative cardiac risk, with event rates ranging from 0.6% with zero factors to 11% or higher with multiple factors 1, 2

Functional Capacity Assessment

• Functional capacity measured in metabolic equivalents (METs) is a critical predictor of perioperative myocardial infarction risk 1, 2, 4
• Patients with excellent functional capacity (≥10 METs) can proceed to surgery without further cardiac testing, even with elevated risk factors 4
• Patients with functional capacity ≥4 METs without symptoms should proceed to planned surgery 1, 2

Surgical Risk Stratification

• The guidelines categorize surgical procedures by cardiac risk: high-risk surgery (>5%), intermediate-risk surgery (1-5%), and low-risk surgery (<1%) 1, 2, 4

Algorithm for Preoperative Testing

• Patients undergoing low-risk surgery should proceed to planned surgery without further cardiac testing, regardless of clinical risk factors 1, 2
• For patients with poor (<4 METs) or unknown functional capacity and 3 or more clinical risk factors scheduled for vascular surgery, consider noninvasive testing if it will change management 1, 2

Perioperative Surveillance for Myocardial Infarction

• ST-segment monitoring is recommended for patients with known coronary artery disease or those undergoing vascular surgery, as ST-segment changes are strong predictors of perioperative myocardial infarction 5, 6, 7
• Routine postoperative troponin screening is reasonable for detecting myocardial injury after noncardiac surgery (MINS) in patients undergoing elevated-risk surgery with cardiovascular risk factors 8

Myocardial Injury After Noncardiac Surgery (MINS)

• MINS is defined as any elevation in cardiac troponin (>99th percentile of upper reference limit) of presumed ischemic origin occurring within 30 days after surgery 8
• The 30-day mortality associated with MINS is approximately 10%, with risks proportional to peak troponin concentration 8
• Predictors of MINS include cardiovascular risk factors and disease, kidney disease, and urgent or emergent surgery 8