Sex differences in clinical outcomes in patients with stable angina and no obstructive coronary artery disease

Background We comparatively evaluated clinical outcomes in men and women presenting with stable angina with no coronary artery disease (CAD), nonobstructive CAD, and obstructive CAD on coronary angiography. Methods We studied all patients >= 20 years with stable angina, undergoing coronary angiography in British Columbia, Canada, from July 1999 to December 2002 (n = 13,695) with maximum follow-up to 3 years. No CAD, nonobstructive CAD, and obstructive CAD were defined as 0%, 1% to 49%, and >= 50% luminal narrowing in any epicardial coronary artery, respectively. Freedom from major adverse cardiac events (MACEs), which included the combined end points of all-cause mortality, nonfatal acute myocardial infarction, nonfatal stroke, and heart failure admissions, was estimated using the KaplanMeier method. Hazard ratios (HRs) and 95% CIs for MACE were estimated up to 3 years postcatheterization and compared between sex and CAD groups. Results Within the first year, women with nonobstructive CAD had a higher risk of MACE than men with nonobstructive CAD (adjusted HR 2.43, 95% CI 1.08-5.49). Furthermore, women with nonobstructive CAD had a 2.55-fold higher risk of MACE than women with no CAD (95% CI 1.33-4.88). In contrast, men with nonobstructive CAD had a similar risk as men with no CAD (adjusted HR 0.61, 95% CI 0.26-1.45). The differences in MACE according to extent of CAD were not evident in the longer term. Conclusions Women with stable angina and nonobstructive CAD are 3 times more likely to experience a cardiac event within the first year of cardiac catheterization than men. A prospective trial to examine the impact of medical therapy on MACE in patients with nonobstructive CAD is warranted.