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Clinical Articles, Lead Article

Still “chipping away” at ethnic differences in AF

White people have an increased risk of atrial fibrillation (AF) whether compared with black, Asian, or Hispanic people, with the heightened risk being most pronounced in the absence of cardiovascular comorbidities, according to a study1 published recently in Circulation.

Because the association between AF and race has only been rigorously compared in population-based studies that dichotomised participants as white or black, the authors considered it unclear whether white race confers elevated AF risk or black race affords AF protection.

Authors led by Dr Gregory Marcus (University of California, San Francisco) used the Healthcare Cost and Utilization Project to identify patients receiving hospital-based care in California between January 1, 2005 and December 31, 2009. The association between race and incident AF was examined using Cox proportional hazards models.

Interaction analyses were performed to elucidate the mechanism underlying the race-AF association. Among 13,967,949 patients, 375,318 incident AF episodes were observed over a median 3.2 (interquartile range 1.8–4.3) years. In multivariable Cox models adjusting for patient demographics and established AF risk factors, blacks (hazard ratio, 0.84; 95% confidence interval, 0.82–0.85; P<0.001), Hispanics (hazard ratio, 0.78; 95% confidence interval, 0.77–0.79; P<0.001), and Asians (hazard ratio, 0.78; 95% confidence interval, 0.77–0.79; P<0.001) each exhibited a lower AF risk compared with whites.

Screen shot 2013-12-20 at 16.00.54 1

Dr Gregory Marcus (University of California, San Francisco)

AF risk among whites was disproportionately higher in the absence of acquired cardiovascular risk factors and diminished or reversed in the presence of comorbid diseases. Although Hispanics and Asians also had a lower adjusted risk of incident atrial flutter compared with whites, the risk of flutter was significantly higher among blacks.

Speaking to BJC Arrhythmia Watch, Dr Marcus said: “We don’t understand why whites have an increased risk of AF compared to other racial or ethnic groups, and we believe that understanding these differences may bring new information that is critically important to the basic cause of AF regardless of their racial/ ethnic background. We are slowly chipping away at understanding these differences, and this current paper provides two new relevant findings.”

“First, it was previously thought that African Americans were ‘protected’ against AF. Our observation that all other races exhibited significantly lower rates of AF suggests that in fact there is something about being white, or having European ancestry, that appears to enhance the risk of AF,” he continued.

“Second, by looking at numerous interactions between known cardiovascular risk factors and this race-AF relationship, we found that the increased risk among whites was strongest in the absence of other cardiovascular risk factors. We believe that this may suggest that the racial differences are most relevant to ‘lone’ AF (which is known to be most closely associated with inherited or genetically-mediated AF), whereas the presence of certain cardiovascular risk factors (such as hypertension or heart failure) may ultimately lead down a path of a different form of AF that is a long-term consequence of the stress on the heart from those risk factors,” Dr Marcus added.

“This is a very rich area for research, and we continue to explore several avenues, including both genetic and environmental differences between races that might explain the difference and thereby reveal some as yet unknown key factor in the cause of AF,” he concluded.


1. Dewland TA, Olgin JE, Vittinghoff E, Marcus GM. Incident atrial fibrillation among asians, hispanics, blacks, and whites. Circulation 2013;128:2470–7.​CIRCULATIONAHA.113.002449

Published on: December 20, 2013

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  • ArrhythmiaAlliance
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