Characterization and outcomes of women and men with non-ST-segment elevation myocardial infarction and nonobstructive coronary artery disease: results from the Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes with Early Implementation of the ACC/AHA Guidelines (CRUSADE) quality improvement initiative.

BACKGROUND: Women with non-ST-segment elevation myocardial infarction (NSTEMI) who undergo coronary angiography have no obstructive coronary lesions more often than men. Sex-specific characteristics and outcomes of patients without obstructive coronary artery disease (CAD) have not been described previously.

METHODS: Using data from NSTEMI patients enrolled in CRUSADE from 2001 to 2005, we evaluated differences in clinical features and in-hospital outcomes between men and women with no obstructive CAD.

RESULTS: After excluding patients with missing catheterization and sex data (n = 1,494), previous coronary artery bypass grafting or percutaneous coronary intervention (47,907), catheterization contraindications (n = 6,588), and missing obstructive CAD status (n = 1,565), there were 55,514 patients (68.4%) with NSTE acute coronary syndromes (ACS) who underwent angiography (among women, 62.1% [21,294/34,290], and among men, 73% [34,220/46,875]; P < .001). Among these, a total of 5,538 patients (10.0%) had nonnonobstructive CAD-15.1% (3,221/21,294) of women and 6.8% (2,317/34,220) of men (P < .0001). In patients without obstructive CAD, women were as likely as men to have MI (troponin elevation in 89% vs 87%, P = .37). Women and men were equally likely to have larger troponin elevations (58.9% vs 58.6% with troponin >5x upper limit of normal, P = .69, respectively). In NSTEMI patients without obstructive CAD, in-hospital death (0.6% women vs 0.7% men) and cardiogenic shock (1.0% women vs 0.7% men) were infrequent.

CONCLUSIONS: Among NSTE ACS patients undergoing coronary angiography, absence of obstructive CAD is more common in women than men. Although nonobstructive CAD was twice as common among women with NSTEMI, sex differences in characteristics and outcomes were similar to those found with obstructive CAD. Unadjusted in-hospital outcomes of NSTEMI patients with nonobstructive CAD are favorable in both sexes. Whether the underlying pathophysiology of NSTE ACS without documentation of obstructive CAD is different between women and men requires further study.