Posted on 11/21/2012

Researchers have determined that postmenopausal women have specific independent risk factors that drive their incidence of sudden cardiac death (SCD) and being African American is one of them.

African-American women had a significant 61% increased risk of SCD compared with other races, after all known risk factors and sociodemographic risk factors were accounted for, according to Monica L. Bertoia, MPH, PhD, of Harvard School of Public Health in Boston, and colleagues.

Of the 418 women who experienced SCD, investigators identified these characteristics, in addition to traditional risk factors, that put them at increased risk:

  • African-American race
  • Higher pulse
  • Higher waist-to-hip ratio
  • Elevated white blood cell count
  • Heart failure

Interestingly, coronary artery disease was not previously diagnosed in nearly half of the women who experienced SCD, researchers wrote in the study published online in the Journal of the American College of Cardiology.

Bertoia and colleagues noted the growing population of postmenopausal women whose risk of cardiovascular events increases with age.

They also emphasized the dearth of data regarding women and SCD because they have been historically underrepresented in SCD studies and have fewer events than men. Consequently, little is known about factors that influence SCD in women.

For this study, researchers used the Women's Health Initiative, which included 161,808 women from 40 study sites. The group was enrolled between 1993 and 1998 and had participated in various trials. Their ages spanned 50 to 79.

The investigators reviewed hospital medical records and reports from all relevant procedures, as well as autopsy reports and laboratory results. The mean follow-up time was 10 years.

Women in the study had an overall rate of SCD of 2.4/10,000 women per year. But the rate for African Americans was nearly double the overall rate at 4.3/10,000 women per year. The rate for whites of 2.3/10,000 women per year.

When researchers adjusted the model to exclude women with prior coronary heart disease, the risk for African Americans was not significant (HR 1.34, 95% CI 0.87 to 2.08).

Besides the aforementioned independent risk factors for SCD, there were also several traditional cardiovascular risk factors that held significance, including smoking, diabetes, hypertension, history of myocardial infarction, and history of carotid artery disease.

Having a prior MI was the strongest risk factor for SCD (HR 4.71, 95% CI 3.48 to 6.36); however, hypertension was associated with a larger population-attributable fraction (21.5%) compared with 13.7% for MI. The authors suggested the reason is because of the high prevalence of hypertension in this population.

Bertoia and colleagues also noted that the waist-to-hip ratio, which is a measure of fat distribution, was a "more important risk factor for SCD than BMI."

They surmised that perhaps inflammation plays a part in SCD because abdominal fat "has a greater influence on inflammation than fat stored in other areas of the body."

The study is limited by its observational nature, as well as no data on the subtype of SCD. Additionally, some deaths coded as SCD might be due to other causes.

The investigators suggested that future research concentrate on why African-American women had a 61% increased risk of SCD.

The Women's Health Initiative program is funded by the National Heart, Lung and Blood Institute, NIH, and the U.S. Department of Health and Human Services.

SOURCE: MedPage Today

 

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