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 report 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 in risk. 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.”

Here is the press release from the AHA:

Even moderate smoking associated with sudden death risk in women

• Even light-to-moderate cigarette smoking is associated with a significant increase in the risk of sudden cardiac death in women.
• The risk of sudden cardiac death rose 8 percent for each five years of smoking.
• However, within 15-20 years of smoking cessation the risk of sudden cardiac death drops to that of a nonsmoker.

DALLAS, Dec. 11, 2012 — Women who are even light-to-moderate cigarette smokers may be significantly more likely than nonsmokers to suffer sudden cardiac death , according to new research in Circulation: Arrhythmia & Electrophysiology, an American Heart Association journal.

The findings indicate long-term smokers may be at even greater risk. But quitting smoking can reduce and eliminate the risk over time.

“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 effected the risk among apparently healthy women, nor did we have long-term follow-up,” said Roopinder K. Sandhu, M.D., M.P.H., the study’s lead author and a cardiac electrophysiologist at the University of Alberta’s Mazankowski Heart Institute in Edmonton, Alberta, Canada.

Researchers examined the incidence of sudden cardiac death among more than 101,000 healthy women in the Nurses’ Health Study, which has collected biannual health questionnaires from female nurses nationwide since 1976. They included records dating back to 1980 with 30 years of follow-up. Most of the participants were white, and all were between 30 to 55 years old at the study’s start. On average, those who smoked reported that they started in their late teens.

During the study, 351 participants died of sudden cardiac death.

Other findings include:

• Light-to-moderate smokers, defined in this study as those who smoked one to 14 cigarettes daily, had nearly two times the risk of sudden cardiac death as their nonsmoking counterparts.
• Women with no history of heart disease, cancer, or stroke who smoked had almost two and a half times the risk of sudden cardiac death compared with healthy women who never smoked.
• For every five years of continued smoking, the risk climbed by 8 percent.
• Among women with heart disease, the risk of sudden cardiac death dropped to that of a nonsmoker within 15 to 20 years after smoking cessation. In the absence of heart disease, there was an immediate reduction in sudden cardiac death risk, occurring in fewer than five years.

Sudden cardiac death results from the abrupt loss of heart function, usually within minutes after the heart stops. It’s a primary cause of heart-related deaths, accounting for between 300,000-400,000 deaths in the United States each year.

“Sudden cardiac death is often the first sign of heart disease among women, so lifestyle changes that reduce that risk are particularly important,” said Sandhu, who is also a visiting scientist at Brigham and Women’s Hospital in Boston, Mass. “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.”

Co-authors are Monik C. Jimenez, Sc.D.; Stephanie E. Chiuve, Sc.D.; Kathryn C. Fitzgerald, M.Sc.; Stacey A. Kenfield, Sc.D.; Usha B. Tedrow, M.D.; and Christine M. Albert, M.D., M.P.H. Author disclosures are on the manuscript.

The National Institutes of Health and the American Heart Association funded the study.

Learn more from the American Heart Association on the benefits of not smoking and how to quit smoking.  Learn more about the unique heart disease risks women face and how to beat them at www.GoRedForWomen.org .

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