Sex differences in early mortality after myocardial infarction (MI) vary by age. MI with nonobstructive coronary arteries (MINOCA [<50% stenosis]) is more common among younger patients and women, and MINOCA has a better prognosis than MI with obstructive coronary artery disease (MI-CAD). The relationship between age, sex, and obstructive CAD status and outcomes post-MI has not been established.

Adults who underwent coronary angiography for acute ST-segment–elevation and non–ST-segment–elevation MI in the National Cardiovascular Data Registry ACTION Registry-GWTG (Acute Coronary Treatment and Intervention Outcomes Network Registry–Get With the Guidelines) from 2007 to 2014 were identified. Patients with cardiac arrest, thrombolytic therapy, prior revascularization, or missing demographic or angiographic data were excluded. The primary outcome was all-cause, in-hospital mortality. Secondary outcomes included major adverse cardiovascular events. Demographics, clinical history, presentation, and in-hospital treatments were compared by sex and CAD status (MI-CAD or MINOCA). Mortality and major adverse cardiovascular outcomes were analyzed by age, sex, and CAD status. Among 322 523 patients with MI, MINOCA occurred in 18 918 (5.9%). MINOCA was more common in women than men (10.5% versus 3.4%; P<0.0001), and women had higher mortality than men overall (3.6% versus 2.4%; P<0.0001). In-hospital mortality was lower after MINOCA than MI-CAD (1.1% versus 2.9%; P<0.0001). Among patients with MI-CAD, women had higher mortality than men (3.9% versus 2.4%; P<0.0001) while no sex difference in mortality was observed with MINOCA (1.1% versus 1.0%; P=0.84). The higher risk of post-MI death among women with MI-CAD was most pronounced at younger ages.

MINOCA was associated with lower mortality than MI-CAD. Higher risk of post-MI death among women in comparison to men was restricted to patients with MI-CAD.