Smoking cigarettes may more than double a woman's risk of sudden cardiac death. But quitting can reduce that risk significantly over time, according to a new study.
Sudden cardiac death is a sudden, unexpected death caused by loss of heart function. It is the leading cause of heart-related deaths in the U.S. and is responsible for up to 400,000 deaths per year.
Researchers found that women who were current smokers were two-and-a-half times more likely to suffer sudden cardiac death than nonsmokers. The risk of sudden cardiac death was even higher among heavy and lifetime smokers.
"We found the more that you smoke, the higher the risk of sudden cardiac death," says researcher Roopinder Sandhu, MD, MPH, assistant professor of medicine at the University of Alberta in Alberta, Canada. "But the important thing is that this risk can be eliminated after smoking cessation."
The study showed that quitting smoking had an almost immediate effect in reducing the risk of sudden cardiac death within five years among women without any symptoms of heart disease.
For women already diagnosed with heart disease, the benefits of quitting smoking took much longer to take effect.
First Sign of Trouble
Researchers say for many women, sudden cardiac death is the first sign of heart disease.
Although smoking is a known risk factor for sudden cardiac death, researchers say few studies have looked at the nature of this relationship in a large number of women both with and without heart disease.
This study looked at the impact of smoking and smoking cessation on the risk of sudden cardiac death among 101,018 women who took part in the Nurses' Health Study. The results appear in Circulation: Arrhythmia & Electrophysiology.
During 30 years of follow-up, 351 cases of sudden cardiac death were reported.
Researchers found the amount and duration of cigarette smoking was strongly associated with the women's risk of sudden cardiac death.
"Even with a very small amount, one to 14 cigarettes per day, women's risk of sudden cardiac death was almost two-fold higher compared to women who did not smoke," says Sandhu, who conducted the study as a visiting scientist at Brigham and Women's Hospital in Boston.
Overall, the study showed:
"This is an important study because it links smoking to sudden cardiac death in those unfortunate women who don't make it to the hospital," says Nieca Goldberg, MD, medical director of the women's heart program at New York University's Langone Medical Center.
"The study shows that even modest levels of smoking can increase the risk of sudden cardiac death," says Goldberg, a spokesperson for the American Heart Association. "People should know that just one cigarette is too much."
Quitting Cuts Risk
Researchers also found quitting smoking had different effects on women's sudden death risk depending on their heart disease status.
The risk of sudden cardiac death decreased almost immediately among women who quit smoking with no history of heart disease.
But this risk reduction was delayed among women who already had heart disease and quit smoking. For these women, the risk of sudden cardiac death dropped to that of non-smokers about 15-20 years after smoking cessation.
Sandhu says that may be because nicotine has both short- and long-term negative effects on the heart.
First, nicotine is thought to have some immediate effects that can lead to life-threatening irregular heartbeats and sudden cardiac death.
Second, cigarette smoke causes scarring of the heart tissue. This effect may persist long after quitting and contribute to the risk of sudden cardiac death.
"Cigarette smoking is an important modifiable risk factor for sudden cardiac death for women both with and without heart disease," Sandhu says. "Women shouldn't wait until the development of heart disease to quit."
Jennifer Warner - WebMD
