NEW YORK (Reuters Health) – Postmenopausal African American women in the Women’s Health Initiative (WHI) study had lower rates of atrial fibrillation (AF) than postmenopausal white women.
Still, once AF occurs in black women, it’s just as problematic as in white women, one researcher pointed out.
Lower rates of AF have been consistently reported in African Americans compared with whites, but unlike in whites, there have been no common variants associated with AF in African Americans with genome-wide statistical significance.
Dr. Marco V. Perez from Stanford University School of Medicine in Stanford, California and colleagues used WHI data to look for differences in rates of AF between African Americans and whites and associations between AF and common genomic variants previously associated with AF in European populations.
They also wanted to replicate the association between genome-wide European ancestry and AF in the African American women.
Altogether they had data from more than 80,000 women, including 7,234 who were African American, according to the August 9th report online in the American Heart Journal.
African American race was associated with a 57% reduction in the rate of incident AF after adjustment for age, diabetes, coronary heart disease, congestive heart failure, peripheral arterial disease, body mass index, use of hormone therapy, smoking, and higher education.
Among the African American women, genome-wide European ancestry was not significantly associated with AF after adjustment for age, congestive heart failure, myocardial infarction, body mass index, and hypertension.
Moreover, none of the 13 single nucleotide polymorphisms that had previously been reported as associated with AF in European cohorts was significantly associated with AF in these African American women.
“Ethnic differences in disease rates found in multivariate analyses imply that there are (1) unmeasured environmental exposures accounting for these disparities, (2) genomic factors driving different rates of disease, or (3) a combination of these two factors,” the investigators explain.
“More thorough environmental characterization and studies of ancestry informative markers in African American populations will need to be performed to help identify the factors that account for the differences in rates of AF between different ethnicities,” the researchers say.
“Meta-analyses combining several large African American cohorts are ongoing to identify novel variants associated with AF in this understudied population,” they add.
“In general, I was not surprised by the findings of the study,” Dr. Gian M. Novaro from Cleveland Clinic Florida, Weston, Florida, who has published research on AF, told Reuters Health. “They are consistent with most prior analyses on race and incident AF; namely that African American race was significantly associated with a lower rate of AF.”
“The study is significant for extending the prior observation of racial disparity in AF occurrence to a large group of African American women,” Dr. Novaro said. “It’s also interesting that none of the previously identified polymorphisms (DNA sequence variations) linked to AF in European populations were associated with AF in these African American women. This tells us that we still don’t know why African Americans develop less AF compared to whites, and that there are yet no identified common gene variants associated with AF among African Americans.”
“As best as we can tell from available data, the management strategies of AF should not differ by race,” Dr. Novaro added. “Although African American women seem to have a lower chance of developing AF, physicians should remain equally vigilant of its occurrence; that is because once AF develops, the related consequences of AF (i.e., stroke, heart failure) are no different between races.”
Dr. Perez did not respond to a request for comments on this report.
Am Heart J 2013.