Increased Rates of Stroke, Heart Failure, CHD, and Death in Black Individuals with Atrial Fibrillation

In a study published online by JAMA Cardiology, Jared W. Magnani, M.D., M.Sc., formerly of the Boston University School of Medicine, and colleagues examined race-specific associations of atrial fibrillation with stroke, heart failure, coronary heart disease (CHD), and all-cause mortality among more than 15,000 individuals.1

Atrial fibrillation (AF) is a common cardiac arrhythmia with significant adverse outcomes and high social and medical costs. In the United States, AF affects approximately 1 percent of the adult population and more than 5 percent of those 65 years and older. The study of AF and its associated adverse outcomes has been conducted predominantly in studies with participants of mostly white race. For this analysis, the researchers used data from the Atherosclerosis Risk in Communities (ARIC) Study, which from 1987 through 1989 enrolled 15,792 men and women and conducted 4 follow-up examinations (2011-2013) with active surveillance for vital status and hospitalizations. Race was determined by self-report and categorized as white, black, or other.

After exclusions, 15,080 participants (average age, 54 years; 56 percent women; 25 percent black individuals) were included in this analysis. During an average follow-up of 21 years, there were 2,348 cases of incident AF. There was a higher incidence of AF in white individuals compared with black individuals. Both white and black individuals with AF had markedly increased risks of the outcomes of stroke, heart failure, CHD, and all-cause mortality. The rate differences (the difference in incidence rates in those with and without AF) of the outcomes differed by race. Black individuals with AF had an approximately 1.5- to 2.0-fold greater rate difference for each outcome than white individuals with AF.

“Our results contribute toward understanding the significant racial differences in black and white individuals with AF. Further study must now address the mechanisms for such differences to improve treatment of AF and prevent complications. Likewise, continued investigation of the causes and origins for such racial differences may identify racial disparities and suggest approaches to address and mitigate them,” the authors write.

“Magnani and colleagues importantly add to the literature another in the long list of studies showing cardiovascular disorders with either an increase in incidence or worse outcome in black individuals compared with white individuals, including patients with heart failure, stroke, or coronary artery disease,” write Thomas D. Stamos, M.D., and Dawood Darbar, M.D., of the University of Illinois at Chicago, in an accompanying editorial.2

“The reason for these disparities remains unclear. Despite an intense search over the last decade, no consistent genetic cause has been identified. What is known is that there are a number of socioeconomic factors found more commonly among black individuals that strongly correlate with worse cardiovascular outcomes. There are many studies demonstrating the influence of neighborhood social environment and the risk of adverse health events. The possibility that these social determinants of health are playing a direct causative role through an epigenetic mechanism is an interesting, but still unproven theory.”

References:

1. JAMA Cardiology. Published online June 22, 2016; doi:10.1001/jamacardio.2016.1025.

2. JAMA Cardiology. Published online June 22, 2016; doi:10.1001/jamacardio.2016.1259.