December 11th, 2012

No Surprise: Smoking and Sudden Cardiac Death Closely Tied

Although cigarette smoking has long been linked to cardiovascular (CV) disease and sudden cardiac death (SCD),  the precise contribution of smoking, and the effect of smoking discontinuation, on SCD has not been clear. Now a new study from the Nurses’ Health Study published in Circulation: Arrhythmia & Electrophysiology provides new clarity about the relationship between smoking and SCD.

“Cigarette smoking is a known risk factor for sudden cardiac death, but until now, we didn’t know how the quantity and duration of smoking affected the risk among apparently healthy women, nor did we have long-term follow-up,” said lead investigator Roopinder Sandhu, in an AHA press release.

Dr. Sandhu and colleagues analyzed data from more than 100,000 women without known CV disease or cancer.  During 30 years of followup there were 351 incident SCDs. Compared to women who never smoked, the risk of SCD was significantly elevated in current smokers (relative risk 2.44) and former smokers (RR 1.40).

The number of cigarettes smoked each day was correlated with the increase in SCD risk, but even women who smoked only 1-14 cigarettes per day had a significant 1.84-fold increase in risk. Women who smoked more than 25 cigarettes a day had a 3.3-fold increase. Smoking duration was also significant, resulting in an 8% increase in SCD risk for every 5 years of smoking.

Women who quit smoking reduced their SCD risk. After 15 years the reduction in risk achieved statistical significance, and by 20 years the risk was similar to women who had never smoked.

In an exploratory analysis, women smokers with coronary heart disease (CHD) had a much higher incidence of SCD than women without CHD. Women with CHD who quit smoking did not enjoy the same immediate reduction in SCD risk as observed in women without CHD.

“Sudden cardiac death is often the first sign of heart disease among women, so lifestyle changes that reduce that risk are particularly important,” said Dr. Sandhu. “Our study shows that cigarette smoking is an important modifiable risk factor for sudden cardiac death among all women. Quitting smoking before heart disease develops is critical.”

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