A prospective study looking back at a database of 101,018 nurses from the Nurses Health Study examined smoking habits and incidence of sudden cardiac death. The study conducted by researchers of University of Alberta, Harvard School of Public Health, and Birmingham Women’s Hospital found that sudden cardiac death (SCD) and risk of SCD was significantly reduced after smoking women quit.
Over a 30 year period, biannually, the cohort of women were asked about their smoking habits. This included number of cigarettes smoked daily and duration of smoking. At baseline in 1980, 44.5% never smoked, 26.4% were past smokers, and 29.1% were current smokers. By the end of the study there were 351 confirmed cases of sudden cardiac death.
The data showed that those who smoked a less than extreme amount, 1-14 cigarettes daily, had elevated risk of SCD compared to non-smokers yielding a hazard ratio of 1.84 at a 95% confidence interval from 1.16 to 2.92. Furthermore, every additional 5 years of smoking was linked to an 8% greater risk with HR of 1.08, 95% CI from 1.05 to 1.12. SCD risk was linearly associated with quantity of cigarettes smoked daily and duration of smoking. Finally, women who quit smoking after developing coronary heart disease (CHD) had their risk level for SCD nearly par the risk level of non-smokers (HR: 0.45, 95% CI from 0.31 to 0.64 and HR: 0.40, 95% CI from 0.30 to 0.54 respectively) after 20 years. However, the risk level for women who had not developed CHD returned to levels near non-smokers after only 5 years.
This shows a strong association, causality if you will, from smoking to risk of sudden cardiac death.
Roopinder K. Sandhu, Monik C. Jimenez, Stephanie E. Chiuve, Kathryn C. Fitzgerald, Stacey A. Kenfield, Usha B. Tedrow, Christine M. Albert. 2012. Smoking, Smoking Cessation and Risk of Sudden Cardiac Death in Women. Circulation: Arrhythmia and Electrophysiology.