Late residual risk between 12 and 36 months after event-free survival following acute myocardial infarction

Background

Although early outcomes after acute myocardial infarction (AMI) have improved, late residual risk beyond the first year remains insufficiently defined. We investigated predictors of late mortality and major adverse cardiovascular events (MACE) among patients who remained event-free during the first year after AMI.

Methods

From the Korean Acute Myocardial Infarction Registry-V (KAMIR-V), a nationwide multicenter registry including 38 primary PCI centers in South Korea, 16,177 consecutive AMI patients were enrolled between January 2016 and June 2020. Among them, 14,979 underwent percutaneous coronary intervention (PCI) during index hospitalization and comprised the study population. Of these, 13,884 patients were free from MACE at 12 months and formed the landmark cohort. The primary endpoint was all-cause death between 12 and 36 months; the secondary endpoint was MACE (death, non-fatal myocardial infarction, or ischemic stroke) during the same period. Multivariable Cox regression was performed to identify independent predictors.

Results

In the 12-month event-free PCI cohort (n=13,884), mean age was 63.5±12.3 years and 78.7% were male; 15.7% had renal dysfunction (eGFR<60 mL/min/1.73 m²), 27.0% had diabetes, 17.1% had Killip class ≥II, 11.2% had LVEF<40%, and 52.7% had multivessel disease. ST-elevation myocardial infarction accounted for 6,890 patients, with a median door-to-balloon time of 63 (50–83) minutes.

Between 12 and 36 months, all-cause death occurred in 2.2% and MACE in 3.5% of patients. Independent predictors of late death, ranked by adjusted hazard ratio (HR), were renal dysfunction (HR 2.25), LVEF<40% (HR 1.90), prior heart failure (HR 1.83), diabetes (HR 1.72), Killip ≥II (HR 1.58), prior myocardial infarction (HR 1.46), male sex (HR 1.35), and older age (HR 1.07 per year), whereas higher BMI was inversely associated (HR 0.95 per kg/m²). For late MACE, renal dysfunction (HR 1.91), diabetes (HR 1.69), prior myocardial infarction (HR 1.67), prior heart failure (HR 1.70), LVEF<40% (HR 1.53), Killip ≥II (HR 1.43), and older age (HR 1.04 per year) remained significant predictors.

Conclusions

Among AMI patients undergoing PCI who were free from major events at 12 months, clinically meaningful late mortality and MACE persisted between 12 and 36 months. Renal dysfunction, residual clinical severity, diabetes, and left ventricular dysfunction were key determinants of late adverse outcomes, supporting the need for continued risk stratification beyond the first year after AMI.