Researchers identify stroke predictors in black patients

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Predictors of atrial fibrillation might offer physicians a better way to prevent stroke in blacks, according to a new study done by researchers at Wake Forest University School of Medicine, Winston-Salem, USA.

Despite low reported prevalence of atrial fibrillation in black patients, they suffer strokes five times more often than white patients and die from them two times more often. That paradox might result from limitations in the methods (electrocardiograms or self-report) used to detect atrial fibrillation, said Dr Elsayed Z Soliman, Epidemiological Cardiology Research Center at the School of Medicine and lead author of the study.


“The limitations stem from the fact that atrial fibrillation is intermittent in at least 30% of patients, and most patients are not aware if they have atrial fibrillation or not,” Soliman said. “Trying to detect atrial fibrillation using an electrocardiogram, or simply counting on patients to know if they have it, leads to underdiagnosis of the condition most of the time. Our research suggests that being proactive in predicting it may be a better approach.”


The study appears in Stroke, the peer-reviewed journal of the American Heart Association and American Stroke Association.


Researchers reviewed electrocardiogram data from the Atherosclerosis Risk in Communities study supported by the National Heart, Lung and Blood Institute. More than 15,000 people in North Carolina, Mississippi, Minnesota and Maryland participated in the study during the 1980s and 90s.


Researchers found that, while electrocardiogram reports of atrial fibrillation were significantly less in black participants than in whites, black participants ultimately suffered more ischemic strokes. However, the analysis uncovered that electrocardiogram on black participants revealed a higher rate of predictors (P-wave terminal force, P-wave duration, P-wave area and PR duration) of future atrial fibrillation than did the electrocardiograms of the white participants.


“With the blacks having more abnormal electrocardiogram predictors of atrial fibrillation, as the results showed, there is a possibility that blacks might actually have a higher prevalence of atrial fibrillation than previous studies have picked up on,” Soliman said. “Blacks may have more ‘intermittent’ atrial fibrillation, the difficult type to detect, which could be the reason why previous studies underestimated diagnosis more in blacks.”


Soliman added that physicians, knowing this, should use the electrocardiogram to evaluate black patients’ risk of stroke by determining if the patient has certain predictors, instead of the condition itself. If so, the patients may be able to be treated with blood thinners as if they have the disease. It is a treatment adjustment that could help prevent stroke, however further investigation into the subject is needed, he said.


“P-wave terminal force in the electrocardiogram may provide a strong independent predictor for incidence stroke and atrial fibrillation in clinical practice,” Soliman said. “For the physician evaluating black patients for the risk of stroke, these results show that you cannot think atrial fibrillation is less common in this population,” Soliman said.


Soliman said that the next step in research on this subject is to do a long-term electrocardiogram study to confirm the hypothesis that atrial fibrillation, especially the intermittent type, has been underdiagnosed in blacks.


“We need further studies using long-term electrocardiogram recording – 48-72 hours – or event monitors to detect atrial fibrillation” he said. “The cost of these tests on population studies has always been an obstacle. However, with the results of this study, it may be worth it.”