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Sex Differences in Clinical Outcomes in Patients With Stable Angina and No Obstructive Coronary Artery Disease
Study Questions:
Do outcomes differ by gender among men and women presenting with stable angina and no coronary artery disease (CAD), nonobstructive CAD, and obstructive CAD on coronary angiography?
Methods:
This cohort included residents of British Columbia (BC), Canada, 20 years or older with stable angina, who underwent coronary angiography between July 1, 1999, and December 31, 2002. Follow-up was obtained through March 31, 2003, with a median follow-up of 1.9 years and maximum follow-up of 3 years. Demographic, clinical characteristics, and outcomes were collected through the Cardiac Services BC Registry (cardiac procedures and patient’s clinical and demographic characteristics), the BC Hospital Discharge Abstract Database (all hospitalization admissions), and the BC Vital Statistics (all death records). No CAD, nonobstructive CAD, and obstructive CAD were defined as 0%, 1-49%, and ≥50% luminal narrowing in any epicardial coronary artery, respectively. Freedom from major adverse cardiac events (MACE), which included the combined endpoints of all-cause mortality, nonfatal acute myocardial infarction, nonfatal stroke, and heart failure admissions, was estimated using the Kaplan-Meier method. Hazard ratios (HRs) and 95% confidence intervals (CIs) for MACE were estimated up to 3 years post-catheterization, and compared between sex and CAD groups.
Results:
Of the 13,695 patients, most had obstructive CAD, a minority had nonobstructive CAD, and 15% had no CAD. More than one-third of women had no CAD compared with <10% of men. Women also had a significantly higher proportion of nonobstructive CAD compared with men. In the nonobstructive CAD category, women were older, had more hypertension and more cancer, but smoked less than men (all p < 0.001). 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). Women with nonobstructive CAD had a 2.55-fold higher risk of MACE than women with no CAD (95% CI, 1.33-4.88). 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. It was also observed that when heart failure was excluded from the MACE outcome, the difference between genders among the nonobstructive group was no longer significant.
Conclusions:
The investigators concluded that 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.
Perspective:
These data are thought provoking. Women with nonobstructive CAD appear to be at higher risk for events than men with nonobstructive CAD. Given that this difference was no longer significant after excluding heart failure in the outcome, perhaps aggressive risk factor prevention and management, in particular for blood pressure among women, would be an important means of reducing events among women with nonobstructive CAD.
Keywords: Stroke, Neoplasms, Myocardial Infarction, Coronary Artery Disease, Follow-Up Studies, Angina, Stable, Cardiac Catheterization, Canada, Blood Pressure, Risk Factors, British Columbia, Coronary Angiography, Cardiovascular Diseases, Hypertension
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