Cigarettes linked to sudden death
Women who smoke even small amounts face higher risk of cardiac arrest: study
Even small amounts of smoking appear to nearly double a woman’s risk of sudden cardiac death, researchers are reporting.
Based on an analysis of more than 100,000 women enrolled in the U.S. Nurses’ Health Study, the new study is one of the first to attempt to quantify how much, and how long, women have to smoke to increase their sudden death risk, and how soon after quitting smoking the risk of early death begins to drop.
Researchers found that “even small-to-moderate” amounts of cigarettes smoked daily — one to 14 per day — were associated with an almost two-fold increase in sudden death.
Not surprisingly, the longer women smoked, the higher their risk. Every five years of continued smoking was associated with an eight per cent increase in sudden cardiac death, said lead author Dr. Roopinder Sandhu, a cardiac electrophysiologist at the University of Alberta’s Mazankowski Heart Institute in Edmonton. Sandhu performed the research in Boston, where she is also a visiting scientist at Brigham and Women’s Hospital.
Most sudden cardiac deaths occur in people without known heart disease. Abnormal heart rhythms are the most common cause. Unless an electric shock is delivered, the person can die within minutes. Each year up to 40,000 Canadians die of sudden cardiac arrest, according to the Heart and Stroke Foundation.
Nicotine may trigger lifethreatening arrhythmias in several ways, Sandhu said. Nicotine can promote plaque build up in heart vessels and stimulate the release of epi- nephrine and norepinephrine, stress hormones that increase heart rate. It can decrease oxygen supply to the blood and make blood platelets stickier, increasing the risk of a blood clot.
For the study, researchers looked at the association between smoking and the risk of sudden cardiac death among 101,018 women enrolled in the nurses’ study who were free of known cardiovascular disease when the study began in 1980.
Every two years, the women, who were aged 30 to 55 at the study’s start, received a followup questionnaire about their medical history, cardiovascular risk factors (including their current smoking status) and any newly diagnosed medical conditions.
During 30 years of followup, the researchers identified 351 women who had died of sudden cardiac death.
Compared to those who had never smoked, smokers had a 2.44-fold increased risk of sudden death after researchers took known risk factors, such as age, diabetes, high blood pressure and high cholesterol into account.
Women who reported smoking one to 14 cigarettes daily had a 1.84-fold increase in sudden cardiac death risk. Women who smoked 25 cigarettes or more had more than a three-fold increased risk of sudden death compared to those who had never smoked.
The longer women smoked, the higher their risk: Women who smoked for more than 35 years were three times more likely to die during the followup than women who never smoked.
For women who quit smoking, their risk of sudden death dropped to that of non-smokers after 20 years of stopping.
The study involved relatively healthy Caucasian women. It’s not clear whether the results could be extrapolated to other ethnic groups, or to men.
The researchers grouped cigarettes smoked per day into three categories: one to 14, 15 to 24, and 25 or more. “So it’s hard to differentiate the (risk from) one cigarette from the 14, but it’s still a small number,” Sandhu said.