Roopinder K. Sandhu, M.D., M.P.H., from the University of Alberta in Edmonton, Canada, and colleagues prospectively examined the correlation between cigarette smoking and smoking cessation on the risk of SCD among 101,018 women from the Nurses' Health Study without CHD, stroke, or cancer at baseline in 1980.During 30 years of follow-up, the researchers identified 351 SCD events. After controlling for coronary risk factors, current smokers had a significant 2.44-fold increased risk of SCD compared with never smokers. Among current smokers, the quantity of cigarettes smoked daily and smoking duration were significantly linearly linked to SCD risk in multivariate analysis. The risk of SCD was significantly increased even with small-to-moderate amounts of cigarette consumption (one to 14 per day; 1.84-fold increased risk) and with every five years of continued smoking (hazard ratio, 1.08). After quitting, there was a linear decrease in the risk of SCD over time, and after 20 years of cessation, the risk was equivalent to that of a never smoker.