Prospective Study of Sudden Cardiac Death Among Women in the United States

Background—There are few data regarding the determinants of sudden cardiac death (SCD) in women, primarily because of their markedly lower rate of SCD compared with men. Nonetheless, existing data, although sparse, suggest possible gender differences in risk factors for SCD. Methods and Results—In this prospective cohort of 121 701 women aged 30 to 55 years at baseline, SCD was defined as death within 1 hour of symptom onset. From 1976 to 1998, 244 SCDs were identified. Although the risk of SCD increased markedly with age, the percentage of cardiac deaths that were sudden decreased. Most (69%) women who suffered a SCD had no history of cardiac disease before their death. However, almost all of the women who died suddenly (94%) had reported at least 1 coronary heart disease risk factor. Smoking, hypertension, and diabetes conferred markedly elevated (2.5- to 4.0-fold) risk of SCD, similar to that conferred by a history of nonfatal myocardial infarction (relative risk, 4.1; 95% confidence interval, 2.9 to 6.7). Family history of myocardial infarction before age 60 years and obesity were associated with moderate (1.6-fold) elevations in risk. With regard to mechanism, 88% of SCDs were classified as arrhythmic. In 76% of these, the first rhythm documented was ventricular tachycardia or ventricular fibrillation. Conclusions—These prospective data suggest that, as in men, coronary heart disease risk factors predict risk of SCD in women and that SCD is usually an arrhythmic death. Therefore, prevention of atherosclerosis or ventricular arrhythmias may reduce the incidence of SCD in women.