Gender May Not Explain Women's Higher Risk of Death from Heart Attack

Takeaway points:

• Several studies have found higher mortality rates for women with severe heart attack compared with men
• Women may tend to be older than men at the time of presentation for acute coronary syndromes, and may also be more likely to have comorbidities
• When adjusted for age and comorbidities, women have similar mortality rates at the time of the heart attack as men

A recent study has shown that current thinking on mortality risk in women who have suffered a severe heart attack may be incorrect; the higher mortality rates seen in women compared to men may be due not to their gender, but rather to the fact that women who suffer heart attacks tend to be older and have more comorbidities.

Although several studies have demonstrated higher mortality rates for women with acute coronary syndromes (ACS) and ST elevation myocardial infarction (STEMI) compared with men, the authors of the current study noted that other studies have shown that “factors including age, comorbidities, and/or disease severity account for much of the differences in mortality rates between men and women” and that “sex did not impact outcome of patients with non–ST elevation ACS.” To determine whether these differences persist among patients undergoing contemporary primary percutaneous coronary intervention (PCI), the authors looked at outcomes data from the Blue Cross Blue Shield of Michigan Cardiovascular Consortium (BMC2) for patients undergoing primary PCI for STEMI and evaluated “the impact of sex on clinical outcomes including mortality.”

They presented their results in the article “The Association of Sex with Outcomes among Patients Undergoing Primary Percutaneous Coronary Intervention for ST Elevation Myocardial Infarction in the Contemporary Era: Insights from the Blue Cross Blue Shield of Michigan Cardiovascular Consortium (BMC2),” published in the January 2011 issue of the American Heart Journal.

The researchers looked at data from 8,771 patients (2,542 women) who underwent primary PCI for STEMI. The primary endpoint for this study was in-hospital death; other endpoints included postprocedural transfusion and in-hospital major adverse cardiovascular events (defined as “the composite of death, MI, stroke/transient ischemic attack [TIA], all CABG, or target lesion revascularization”). Compared to the men in the study, female patients were “older, less likely to be white, and less likely to smoke.” They also presented with more comorbidities (including hypertension, diabetes, congestive heart failure, COPD, etc). Male patients with STEMI were more likely to be “current smokers and have a prior history of MI and/or prior PCI.”

Women in the study were more likely to present in cardiogenic shock; men had higher serum baseline creatinine. Rates of cardiac arrest, ventricular tachycardia, and fibrillation and fluoroscopy time were similar between the groups. The researchers reported no sex-related differences in the number of diseased coronary vessels or the prevalence and severity of stenosis between men and women. Preprocedure management and medication use was comparable for men and women.

According to the authors, women in the study were more likely to receive a transfusion postprocedure and experience gastrointestinal bleeding, contrast-induced nephropathy, stroke/TIA, vascular complications, and in-hospital death compared with men. However, after propensity-matched adjustment, the researchers found that compared with men, “women's odds for in-hospital death were no longer statistically significant,” suggesting that “age and additional comorbidities account for sex-related differences in mortality.” Women remained at higher risk for postprocedure transfusions and vascular complications.

Given that the current study supports previous findings that “women are older at the time of presentation for an ACS as compared with men and are more likely to have comorbidities including hypertension and diabetes,” these results “support the premise that age and comorbidities account for the higher in-hospital rates observed among women undergoing PCI for STEMI, given the lack of a significant difference in mortality rates between men and women after propensity matching.”