Sudden death not surprising in many women
CHICAGOMost women who die from an abrupt loss of heart function (called sudden cardiac death) have no prior history of heart disease. However, 94 percent of these women have at least one cardiac risk factor such as smoking, high blood pressure, high cholesterol, diabetes or obesity, according to a report in todays rapid access issue of Circulation: Journal of the American Heart Association.
Sudden cardiac death (SCD) has been understudied in women because it is more common among men, says Christine M. Albert, M.D., M.P.H., lead author of the study and an assistant professor of medicine at Harvard Medical School, Boston. There are an estimated 400,000 out-of-hospital or emergency room sudden cardiac deaths each year.
There are also data to suggest that risk factors for this type of cardiac death may be different among women, she adds. Thats why we wanted to take a closer look at women in this study. As far as Im aware, this is the largest number of sudden cardiac deaths in women that have been examined.
The researchers analyzed the data from the Nurses Health Study, which included 121,701 women ages 30 to 55. The study followed the women for 22 years (1976 to 1998), documenting medical history, cardiac risk factors, diagnosed disease and death. There were 244 cases of SCD in the study. Sudden cardiac death was defined as death within one hour of the onset of symptoms.
Albert and colleagues found that in 69 percent of the SCD deaths, sudden cardiac death was the first sign of heart disease. However, almost all the women who died suddenly had at least one cardiac risk factor. Smoking should be emphasized as a very strong risk factor, Albert says. The women who smoked 25 or more cigarettes a day had a four-fold increased risk of sudden cardiac death. This level of risk is similar to that of a woman who had a heart attack in the past.
Diabetes was associated with almost a three-fold increased risk of sudden death; hypertension with about a 2.5-fold increased risk; and obesity with a 1.6-fold increased risk. High cholesterol did not appear to significantly elevate risk for sudden cardiac death.
Family history was a risk factor for SCD if the women had a parent who died from it before age 60. So it appears that a genetic factor might be involved, particularly among women who die suddenly at a young age, Albert says.
Albert says the concern is that doctors tend to focus on preventing SCD in patients with documented heart disease and not those with risk factors only. This is not the first study to find that cardiac sudden death usually occurs in people without a history of heart disease, she says.
The researchers also confirmed that the most likely mode of sudden cardiac death is irregular heart rhythm. Research has shown that most sudden deaths in men are caused by a ventricular arrhythmia (a chaotic heart rhythm). The same appears to be true of women, Albert says.
The authors conclude that heart disease risk factors appear to predispose women to sudden cardiac death, just as with men. Albert says the study results imply, but dont prove, that by modifying risk factors (quitting smoking, healthy eating, and controlling blood pressure, cholesterol and diabetes), people might lower their risks for sudden cardiac death.
The research tells doctors and patients that sudden cardiac death does happen to women and not just women with heart disease. The first sign of heart disease might very well be sudden cardiac death, Albert says. The best advice now is for women to lower their risk of coronary heart disease, which might lower their risk of sudden cardiac death. These results highlight the need for more research to better identify women who are at high risk for this devastating event.
Co-authors are Claudia U. Chae, M.D., M.P.H.; Francine Grodstein, Sc.D.; Lynda M. Rose, M.S.; Kathryn M. Rexrode, M.D., M.P.H.; Jeremy N. Ruskin, M.D.; Meir J. Stampfer, M.D., Dr.P.H.; and JoAnn E. Manson, M.D., Dr.P.H.
This research was funded by the National Institutes of Health.