What is the risk of Major Adverse Cardiac Events (MACE) in a patient with American Society of Anesthesiologists (ASA) 4 classification?

Risk of Major Adverse Cardiac Events (MACE) in ASA 4 Patients

Patients with ASA 4 classification have a significantly elevated risk of MACE, with rates exceeding 5% for perioperative cardiac complications due to their severe systemic disease that poses a constant threat to life.

Understanding ASA 4 Classification

• The American Society of Anesthesiologists (ASA) defines ASA IV as a patient with severe systemic disease that is a constant threat to life 1
• ASA 4 patients have severe systemic diseases with substantive functional limitations that pose a constant threat to life, representing the highest-risk category of patients who can still undergo elective procedures 1
• Examples of ASA 4 conditions include recent (within 3 months) myocardial infarction, stroke, or TIA, ongoing cardiac ischemia, severe valve dysfunction, and decompensated heart failure 1

MACE Risk in ASA 4 Patients

• ASA 4 classification is independently associated with increased perioperative mortality and morbidity, with cardiac complications being among the most common adverse outcomes 2
• In patients with ASA 4 classification, the risk of MACE is substantially higher than in patients with lower ASA classifications, with rates exceeding 5% for major cardiac complications 2
• The 2024 AHA/ACC guidelines identify ASA classification as a key component in perioperative risk assessment, with ASA 4 patients falling into the "elevated risk" category (≥1% risk of MACE) 2

Risk Factors Contributing to MACE in ASA 4 Patients

• Coronary artery disease (CAD) is prevalent in approximately 18% of patients undergoing major noncardiac surgery and is associated with increased risk of perioperative MACE 2
• History of acute coronary syndrome confers greater perioperative risks than chronic coronary disease, with a 3.5-fold increased risk of perioperative MACE 2
• Heart failure is an established risk factor for poor outcomes after noncardiac surgery, with 90-day mortality rates of 5.49% for symptomatic heart failure patients 2
• Severely reduced left ventricular ejection fraction (LVEF ≤30%) is an independent predictor of 30-day mortality in patients undergoing intermediate and high-risk procedures 2

Risk Assessment Tools

• The Revised Cardiac Risk Index (RCRI) is commonly used to assess perioperative risk of major cardiac complications, though it may have poorer discrimination in patients undergoing vascular surgery 2, 3
• In ASA 4 patients, preoperative B-type natriuretic peptide (BNP) levels can provide additional predictive value for MACE, with higher levels correlating with increased risk 4
• For a cut-off point ≥39 pg/mL, the area under the curve for preoperative BNP was equal to 0.77 in predicting MACE in high-risk orthopedic surgery patients 4
• Functional capacity assessment using tools like the Duke Activity Status Index (DASI) is reasonable to further stratify risk in ASA 4 patients undergoing elevated-risk noncardiac surgery 2

Perioperative Management Considerations

• ASA 4 patients require careful preoperative optimization and may benefit from more intensive perioperative monitoring 2
• Preoperative assessment of left ventricular function is indicated in ASA 4 patients with unexplained cardiac symptoms and may be reasonable with elevated preoperative BNP or NT-proBNP concentrations 2
• For ASA 4 patients with aortic stenosis, elevated-risk elective noncardiac surgery with appropriate intraoperative and postoperative hemodynamic monitoring is reasonable 2
• The risk of residual cardiovascular events remains high in ASA 4 patients despite advances in secondary prevention, particularly with increasing comorbidity burden 5

Common Pitfalls and Caveats

• Underestimation of MACE risk in ASA 4 patients can lead to inadequate perioperative monitoring and management 2
• Not all risk assessment tools perform equally well in predicting MACE in high-risk patients; generic risk scoring systems may perform similarly to cardiac-specific risk scores 3
• The presence of multiple comorbidities in ASA 4 patients has an incremental effect on MACE risk, with each additional comorbidity significantly increasing the risk 5
• Elevated lipoprotein(a) levels may further increase the risk of subsequent MACE in patients with established atherosclerotic cardiovascular disease 6