Abstract
Background: The Universal Definition classifies myocardial infarction (MI) by etiology, but its prognostic implications are uncertain.
Objectives: The goal was to compare the rate and risk of recurrent MI or cardiovascular death among patients with myocardial injury and infarction classified according to the Universal Definition.
Methods: A systematic search of MEDLINE, EMBASE, Central, and Web of Science from January 1, 2007 to July 1, 2025 was performed to identify prospective studies where cardiac troponin was measured for suspected acute coronary syndrome, diagnoses were adjudicated using the Universal Definition, and both MI and cause-specific mortality were reported at a minimum of 1 year. Subdistribution HRs were derived to account for the competing risk of noncardiovascular death. Meta-analysis was performed with random-effects models. The primary outcome was major adverse cardiovascular events (MACE), defined as MI or cardiovascular death. The secondary outcome was noncardiovascular death.
Results: We identified 17 studies of 9 cohorts from 9 countries, with individual patient-level data available in 8 cohorts. Among 120,734 patients (median age: 61.0 years; 45.8% women), type 1 MI occurred in 9.4% (n = 11,298), type 2 MI in 3.0% (n = 3,609), acute myocardial injury in 4.9% (n = 5,864), and chronic myocardial injury in 4.7% (n = 5,625). In patients with type 1 and type 2 MI, the MACE rate was 55.2 and 51.7 per 1,000 patient-years and the noncardiovascular death rate was 25.7 and 60.1 per 1,000 patient-years, respectively. Compared with those without myocardial injury, the risk of MACE (subdistribution HR) was 4.82 (95% CI: 3.55-6.57; I2 = 84%) and 3.36 (95% CI: 2.92-3.86; I2 = 0%), respectively. In patients with acute and chronic myocardial injury, the MACE rate was 47.1 and 44.9 per 1,000 patient-years and the noncardiovascular death rate was 67.0 and 46.9 per 1,000 patient-years, respectively. The risk of MACE was 3.24 (95% CI: 2.41-4.36; I2 = 59%) and 3.03 (95% CI: 2.53-3.62; I2 = 20%), respectively.
Conclusions: All patients with myocardial injury and infarction are at increased risk of future cardiovascular events. However, in type 2 MI, this apparent risk is reduced by a substantially greater competing risk of noncardiovascular death. (PROSPERO Registration: CRD42023464836).