Adherence to a Low-Risk, Healthy Lifestyle and Risk of Sudden Cardiac Death Among Women

Context Sudden cardiac death (SCD) accounts for more than half of all cardiac deaths; the majority of SCD events occur as the first manifestation of heart disease, especially among women. Primary preventive strategies are needed to reduce SCD incidence. Objective To estimate the degree to which adherence to a healthy lifestyle may lower the risk of SCD among women. Design, Setting, and Participants A prospective cohort study of 81 722 US women in the Nurses' Health Study from June 1984 to June 2010. Lifestyle factors were assessed via questionnaires every 2 to 4 years. A low-risk lifestyle was defined as not smoking, body mass index of less than 25, exercise duration of 30 minutes/day or longer, and top 40% of the alternate Mediterranean diet score, which emphasizes high intake of vegetables, fruits, nuts, legumes, whole grains, and fish and moderate intake of alcohol. Main Outcome Measure Sudden cardiac death (defined as death occurring within 1 hour after symptom onset without evidence of circulatory collapse). Results There were 321 cases of SCD during 26 years of follow-up. Women were a mean age of 72 years at the time of the SCD event. All 4 low-risk lifestyle factors were significantly and independently associated with a lower risk of SCD. The absolute risks of SCD were 22 cases/100 000 person-years among women with 0 low-risk factors, 17 cases/100 000 person-years with 1 low-risk factor, 18 cases/100 000 person-years with 2 low-risk factors, 13 cases/100 000 person-years with 3 low-risk factors, and 16 cases/100 000 person-years with 4 low-risk factors. Compared with women with 0 low-risk factors, the multivariable relative risk of SCD was 0.54 (95% confidence interval [CI], 0.34-0.86) for women with 1 low-risk factor, 0.41 (95% CI, 0.25-0.65) for 2 low-risk factors, 0.33 (95% CI, 0.20-0.54) for 3 low-risk factors, and 0.08 (95% CI, 0.03-0.23) for 4 low-risk factors. The proportion of SCD attributable to smoking, inactivity, overweight, and poor diet was 81%(95% CI, 52%-93%). Among women without clinically diagnosed coronary heart disease, the percentage of population attributable risk was 79% (95% CI, 40%-93%). Conclusion Adherence to a low-risk lifestyle is associated with a low risk of SCD.