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07-04-2010 | Cardiology | Article

Larger left atria may explain increased AF prevalence in Whites


Free abstract

MedWire News: The increased prevalence of atrial fibrillation (AF) in White individuals may relate to their having larger left atrial diameters relative to African Americans, report researchers.

Analysis of data from three prospective cohort studies confirmed that the prevalence of electrocardiographically proven AF is higher in White than African–American people; comparison of echocardiographic characteristics in one cohort showed that left atrial diameter was significantly larger in Whites.

Gregory Marcus (University of California, San Francisco, USA) and colleagues pooled primary data from the Heart and Soul Study (n=1014), the Heart and Estrogen-Progestin Replacement Study (HERS; n=2673), and the Osteoporotic Fractures in Men Sleep Study (MrOS; n=2911).

Based on protocol-driven electrocardiogram (ECG) findings, a total of 268 participants had AF. These comprised 42 (4%) participants in the Heart and Soul Study, 88 (3%) in the HERS, and 138 (5%) in the MrOS, Marcus and co-authors report in the American Journal of Medicine.

Analysis revealed that significantly more White participants had AF than did all other races combined, while fewer African Americans had AF than all other races combined, whereas Asian and Latin–American individuals had no difference in prevalence versus all other groups combined.

The largest difference in AF prevalence was seen when White and African–American groups were compared: 251 (5%) of Whites versus 6 (1%) of African Americans had AF.

After adjusting for potential confounders including age, gender, body mass index, heart failure, statin use, and ACE inhibitor or angiotensin receptor blocker use, White individuals had a 3.8-fold higher odds of AF compared with African Americans (p=0.002), and a 2.4-fold higher odds compared with any other race (p=0.001). African Americans had a 72% lower odds of AF compared with all other races (p=0.003).

Further analysis of echocardiographic findings from the Heart and Soul Study indicated that White individuals had an average 2-mm greater left atrial diameter compared with African Americans (p<0.001), after adjusting for confounders including age, hypertension, BMI, and ventricular septal thickness.

The authors conclude: “Caucasians have substantially greater risk of developing AF than African Americans. After adjusting for potential confounders, atrial volumes and function are similar in the two races, but atrial diameter is significantly larger in Caucasians.

“The difference is small, but there is evidence in other studies that differences of this magnitude can be a cause of AF.”

MedWire ( is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Caroline Price

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