Is peri‑operative myocardial infarction (PMI) the same as myocardial injury after non‑cardiac surgery (MINS)?

PMI and MINS Are Not the Same

No, perioperative myocardial infarction (PMI) and myocardial injury after non-cardiac surgery (MINS) are distinct but overlapping entities, with MINS representing a broader spectrum that encompasses PMI as well as asymptomatic myocardial injury.

Key Conceptual Distinction

According to the 2024 AHA/ACC guidelines, perioperative myocardial injury exists on a spectrum 1:

• PMI (Perioperative Myocardial Infarction) is defined by overt clinical presentation including:

  • Ischemic symptoms
  • Electrocardiographic changes
  • Pathologic Q-waves
  • Evidence on imaging of loss of viable myocardium

• MINS (Myocardial Injury After Non-cardiac Surgery) is a broader umbrella term that includes:

  • Both Type 1 and Type 2 MI
  • Asymptomatic myocardial injury (the critical difference)
  • Any elevated cardiac troponin >99th percentile of upper reference limit
  • Presumed ischemic origin (excluding non-ischemic causes like PE, stroke, sepsis)

Why This Distinction Matters Clinically

The fundamental reason MINS was created as a separate entity is that surgical patients often cannot report ischemic symptoms due to anesthesia, analgesia, or distracting surgical site pain 1. This means traditional PMI criteria would miss 80-90% of patients with prognostically significant myocardial injury 1.

Mortality Impact

Both conditions carry substantial mortality risk, but the scope differs 1:

• MINS overall: ~10% 30-day mortality
• Highest troponin quartile: 17% mortality
• Even asymptomatic MINS (without ischemic symptoms): substantial 30-day mortality
• MINS with ischemic features: 5-fold greater hazard of 30-day mortality
• MINS without ischemic features: 3-fold greater hazard of 30-day mortality

Diagnostic Framework

MINS diagnosis requires 1:

1. ≥1 elevated troponin (>99th percentile)
2. Presumed ischemic origin
3. Exclusion of non-ischemic causes (PE, sepsis, acute HF, stroke)
4. Does NOT require symptoms or ECG changes

PMI diagnosis requires 1:

1. All MINS criteria PLUS
2. Clinical ischemic symptoms OR
3. ECG changes OR
4. Imaging evidence of myocardial loss

Clinical Management Implications

The 2024 guidelines recommend different surveillance approaches based on this distinction 1:

• High-risk patients: Troponin surveillance to detect MINS (including asymptomatic cases)
• Low-risk patients: No routine screening without symptoms (Class 2, LOE B-NR)
• All MINS patients: Outpatient follow-up for cardiovascular risk optimization (Class 2a, LOE B-NR)
• MINS patients: Consider antithrombotic therapy (Class 2b, LOE C-LD)

Common Pitfall to Avoid

Do not wait for symptoms or ECG changes to diagnose perioperative myocardial injury in surgical patients. The absence of classic anginal symptoms does not exclude significant myocardial injury with prognostic implications 2, 3. Troponin surveillance in appropriate-risk patients is essential because 80-90% of MINS cases are asymptomatic 1.

Summary of Relationship

Think of it hierarchically:

• Perioperative myocardial injury (broadest term, ~20% of NCS patients)
  • MINS (troponin elevation of ischemic origin)
    • Asymptomatic MINS (80-90% of MINS cases)
    • PMI (symptomatic or ECG/imaging-evident MI, 10-20% of MINS cases)

MINS is the clinically relevant umbrella term for perioperative practice because it captures the full spectrum of prognostically important myocardial injury, whereas PMI represents only the symptomatic tip of the iceberg 4, 5, 6.