In a US community-based study of patients aged ≤65 years between 2003 and 2018, researchers identified 1,474 index myocardial infarction (MI) events and classified them into six pathophysiologic mechanisms: atherothrombosis, spontaneous coronary artery dissection (SCAD), embolism, vasospasm, MI with nonobstructed coronary arteries of uncertain cause (MINOCA-U), and supply/demand mismatch secondary MI (SSDM). While atherothrombosis accounted for 68% of cases, nonatherothrombotic causes were particularly common in women, who had lower overall incidence of MI but a higher proportion due to SCAD, SSDM, and other mechanisms. SCAD incidence was more than three times higher in women, with over half of cases misclassified as MINOCA or atherothrombosis at presentation. Women with atherothrombosis had similar age and disease extent as men but greater risk factor burden. Long-term outcomes showed highest 5-year all-cause mortality after SSDM (33%), while cardiovascular mortality was low across groups. These findings highlight the significant role of nonatherothrombotic mechanisms in younger adults, especially women, underscoring the need for individualized management and risk stratification. Source: https://www.jacc.org/
