Obstructive vs. nonobstructive coronary artery disease in women and men with myocardial infarction

Background: Information on sex differences in clinical presentation, risk factors and prognostic significance of myocardial infarction (MI) with obstructive vs. nonobstructive coronary artery disease (CAD) is missing as previous studies on nonobstructive CAD have focused on women with the exclusion or under-representation of men. Purpose: This study aimed to identify sex-based differences in risk factors related to obstructive vs. nonobstructive CAD in MI patients. Methods: Data were derived from 9098 acute coronary syndrome patients who underwent coronary angiography. They were admitted to 57 hospitals included in the network of the ISACS-TC registry (ClinicalTrials.gov, NCT01218776) between January 2010 and January 2016. The primary end-points were ST-elevation myocardial infarction (STEMI) as index event and the composite endpoint of all cause 30-day mortality or severe left ventricular dysfunction at discharge (LVD; ejection fraction at echocardiography <40%). Multivariate logistic regression methods were used to identify baseline risk factors that were independent predictors of obstructive vs. nonobstructive CAD. Patients were categorized as having significant CAD (any stenosis≥50%) and nonobstructive CAD (any stenosis 0% to<50%). Patients with unstable angina (n=819) were excluded, giving a final study population of 8279 patients Results: Of the 8279 patients, 91.6% had significant CAD and 8.4% had nonobstructive CAD. Men exhibited less often nonobstructive CAD than women (7.7% vs 10.3%, P<0.001). In nonobstructive CAD, significantly more men than women presented with STEMI (49.9% vs. 36.2%, P=0.001). Smoking (OR 1.55, 95% CI: 1.10–2.18) and male sex (OR: 1.52, 95% CI: 1.08–2.15) were independent determinants for clinical presentation with STEMI. The frequency of the composite endpoint of death or severe LVD was not significantly different between men and women (14.5% vs 11.9%, P=0.34). Sex-specific regression models of obstructive versus non obstructive CAD showed that hypercholesterolemia predicts significant CAD in men (OR: 1.44, 95% CI: 1.17–1.77) and in women (OR: 1.42, 95% CI: 1.04–1.92). However, the predictive risk factors varied considerably for women. The effects of older age (OR: 1.02, 95% CI: 1.01–1.04), diabetes (OR: 2.01, 95% CI: 1.41–2.86) and current/ former smoking (OR 1.95, 95% CI: 1.41–2.69), were stronger in women. The OR for obstructive CAD in men versus women among diabetes and/or smokers was 1.12 (95% CI: 0.90–1.39).Conclusions: Male patients with myocardial infarction are less frequently found to have nonobstructive CAD, but those with nonobstructive CAD have a greater risk of STEMI compared with women. Women are less likely to develop obstructive CAD in the absence of diabetes and smoking. The presence of diabetes or smoking equalizes the odds by sex. These results suggest aggressive life style changes and CAD prevention strategies in women with diabetes and smoking.