Risk factors for sudden cardiac death in post-menopausal women

Objectives: The aim of this study was to estimate the annual incidence rate of sudden cardiac death (SCD) and to identify risk factors for SCD in post-menopausal women.

Background: With the aging U.S. population, post-menopausal women now have the greatest population burden of cardiovascular disease including SCD.

Methods: We examined 161,808 women who participated in the Women's Health Initiative clinical trials and observational study. The women were recruited at 40 clinical sites across the United States, enrolled between 1993 and 1998, and followed until August 2009. Our primary endpoint is incident SCD, defined as death occurring within 1 h of symptom onset or within 1 h after the participant was last seen without symptoms and death that occurred in the absence of a potentially lethal non-coronary disease process.

Results: Four hundred eighteen women experienced adjudicated SCD. The incidence rate of SCD was 2.4/10,000 women/year (95% confidence interval: 2.2 to 2.7). We identified the following independent risk factors for SCD: older age, African-American race, tobacco use, higher pulse, higher waist-to-hip ratio, elevated white blood cell count, history of heart failure, diabetes, history of myocardial infarction, previous carotid artery disease, and hypertension. Population-attributable fractions were greatest for hypertension, waist-to-hip ratio, and myocardial infarction.

Conclusions: Besides traditional risk factors for coronary heart disease, risk factors for sudden cardiac death in post-menopausal women include African-American race, higher pulse, higher waist-to-hip ratio, elevated white blood cell count, and heart failure. Nearly one-half of women who experienced sudden cardiac death had no previous diagnosis of coronary heart disease.