Effect of Gender on Patients With ST-Elevation and Non-ST-Elevation Myocardial Infarction Without Obstructive Coronary Artery Disease

The aim of this study was to compare the prognoses of patients with ST-segment elevation myocardial infarction (STEMI) and those with non-ST-segment elevation myocardial infarction (NSTEMI) without obstructive coronary artery disease (CAD) and the risk associated with gender for future cardiovascular events. The study population was selected from 95,849 patients who underwent coronary angiography for myocardial infarction from 2005 to 2010 and registered in the Swedish Coronary Angiography and Angioplasty Registry (SCAAR). Outcome analyses, including all-cause death, myocardial infarction, congestive heart failure, stroke, and revascularization, were performed in 2,268 patients with STEMI and 10,904 with NSTEMI without obstructive CAD (<50% stenosis). Hazard ratios and 95% confidence intervals comparing women with men were calculated for events, adjusting for cardiovascular risk factors and age. Nonobstructive CAD was found in 7% of patients with STEMI (6% men, 10% women) and in 17% of those with NSTEMI (11% men, 28% women). During a median follow-up of 2.6 years, 8% of patients with STEMI and 5% of those with NSTEMI died. Gender-associated differences in risk were observed in patients with NSTEMI, with adjusted hazard ratios lower in women than men for mortality (hazard ratio 0.90, 95% confidence interval 0.50 to 0.73) and congestive heart failure (hazard ratio 0.61, 95% confidence interval 0.52 to 0.72). In the 2 groups, women underwent less revascularization. In conclusion, nonobstructive CAD was more common in patients with NSTEMI than those with STEMI, as well as in women compared with men. Long-term mortality in patients with nonobstructive CAD was higher after STEMI than NSTEMI. The gender differences in outcomes suggest gender differences in the underlying pathogenesis of myocardial infarction without obstructive CAD.