"Cardiovascular disease is the leading cause of death in both men and women, accounting for one-third of all deaths. Although several studies have shown an improvement of prognosis in women over time, overall outcomes remain worse for women compared with men, providing a strong rationale for focusing on the study of sex-based differences in the outcome of acute coronary syndromes," according to background information in the article. Previous analyses of the differences in outcomes for men and women following ACS have reported conflicting results.
Jeffrey S. Berger, M.D., M.S., of the New York University School of Medicine, New York, and colleagues evaluated the relationship between sex and 30-day mortality following ACS and analyzed factors such as clinical classification at the time of ACS and the severity of angiographic disease. Patients for the study were pooled from a sample of 11 independent, international, randomized ACS clinical trials between 1993 and 2006.
Of the 136,247 patients in this analysis, 38,048 (28 percent) were women. There were 102,004 patients (26 percent women) with ST-segment elevation myocardial infarction (STEMI; a certain pattern on an electrocardiogram following a heart attack); 14,466 with non-STEMI (NSTEMI; 29 percent women); and 19,777 with unstable angina (40 percent women). Women were older and had a higher prevalence of hypertension, hyperlipidemia, diabetes and heart failure. Men were more likely to be smokers and had a higher prevalence of prior heart attack and prior coronary artery bypass graft surgery.
The researchers found that women had a significantly higher unadjusted 30-day risk of death compared with men (9.6 percent vs. 5.3 percent). But after multivariable adjustment for clinical characteristics and clinical presentation, no significant difference was observed in 30-day mortality.
"Perhaps the most striking findings in our analyses relate to the examination of mortality according to type of ACS. We found a significant interaction between sex and type of ACS, such that 30-day mortality risk among women was modestly higher than men only for those patients presenting with STEMI. In patients with NSTEMI and unstable angina, women had a lower adjusted 30-day mortality risk than men. In fact, the strongest finding after full adjustment was lower risk among women with unstable angina," the authors write.
The researchers also found that overall, women who underwent catheterization were more likely to have nonobstructive coronary artery disease and less likely to have multivessel disease compared with men. The relationship between sex and 30-day mortality was similar across the levels of angiographic disease severity.
"Our study suggests a better understanding of the observed sex-based differences. Sex-based differences exist in 30-day mortality among patients with ACS and vary depending on clinical presentation. However, these differences are markedly attenuated following adjustment for clinical differences and angiographic data. The attenuation in the difference in mortality suggests that much of the crude differences are explained by these factors. This study further highlights the clinical and angiographic differences among men and women at presentation with ACS. Understanding and considering these differences may lead to better risk stratification and treatment of all patients with ACS," the researchers conclude.