Myocardial infarction (MI) accounts for a substantial proportion of sudden cardiac deaths (SCD), including cases without obstructive coronary artery disease. The POST SCD (Postmortem Systematic Investigation of Sudden Cardiac Death) study prospectively evaluated the burden of MI-related SCD using countywide autopsy-based adjudication. The findings were published in the Journal of the American College of Cardiology.
Between February 1, 2011, and March 31, 2023, 943 presumed SCD cases were evaluated. Of these, 360 (38%) were attributed to noncardiac causes, while 583 (62%) were autopsy-confirmed SCDs. Among confirmed SCDs, 237 cases (41%) were due to MI, representing approximately one-fourth of all sudden deaths.

Within MI-related SCDs, 214 cases (90%) involved acute or healed MI with obstructive coronary artery disease (MI-CAD), while 23 cases (10%) were classified as acute myocardial infarction with nonobstructive coronary arteries (MINOCA). MINOCA cases were more frequently observed among Black patients (p < 0.05).

Among coronary lesions in acute MI-CAD SCD (n = 95), the left anterior descending artery (38%) and right coronary artery (35%) were most commonly affected, with the right coronary artery identified as the most frequent culprit (43%). Nonarrhythmic causes were more common in MINOCA-related SCD compared with MI-CAD (35% vs 15%; p = 0.037), with a higher observed proportion in Asian patients (p = 0.1). Fibrosis burden was similar between groups (p = 0.6).

These findings indicate that MI contributes substantially to SCD burden, with differences observed by coronary pathology and patient characteristics.