The Impact of Race on Stroke Risk Among Atrial Fibrillation Patients

It’s well reported that African Americans have a lower risk of developing A-Fib as compared to Caucasians.

But it’s a different story regarding strokes. A new study has found that compared with whites, blacks are at increased risk of developing an ischemic stroke either before or after a diagnosis of atrial fibrillation (A-Fib).

A new University of Pennsylvania study found that such strokes may occur even before the patient is aware of having the heart-rhythm problem, and that this risk is higher for black patients. In many cases, the stroke was the red flag that led to the patient’s A-Fib diagnosis.

African Americans and Heart Disease

Heart disease tends to occur earlier in African American patients than in white counterparts.

The death rate from heart-related causes is higher, too, largely due to a higher rate of heart attacks, sudden cardiac arrest, heart failure, and stroke, according to the American Heart Association. 

The Penn Study: Looking Back and Monitoring Forward

Researchers used a centralized pool of patient data from across the University of Pennsylvania Health System, which was comprised of 56,835 patients without a history of atrial fibrillation or a remote history of stroke.

Of these patients, the authors identified 3,507 patients who developed A-Fib. Upon diagnosis, they checked each patient’s medical history for the prior six months to document any history of stroke.

Going forward, the authors monitored these A-Fib patients for strokes for a median of 3.6 years.

Unique Design: The study design was unique in that researchers had a time point that represented the initial diagnosis of atrial fibrillation.

This approach provided an opportunity to examine the risk of stroke during a six-month period prior to a formal, clinical diagnosis of atrial fibrillation. Until now, no prior study has examined stroke risk in this period prior to a diagnosis of atrial fibrillation.

Study Findings

Out of 538 strokes occurring in the study periods, nearly half, 254, occurred before diagnosis with atrial fibrillation.

The authors suspect that in many of those 254 cases, the patients already had A-Fib but were undiagnosed.

Prior Six Months Findings: For the strokes that occurred in the six months before A-Fib diagnosis, the rate in black patients was about one-third higher than the rate in white patients.

Findings after A-Fib Diagnosis: For the strokes that occurred in the years following an A-Fib diagnosis, the rate in black patients was two-thirds higher than in white patients — a 2.5 percent chance of stroke per year in black patients compared with a 1.5 percent chance for whites.

Blood-Thinning Medicines: The increased stroke risk for black patients (with A-Fib) was especially high among those who did not have prescriptions for blood-thinning medicines (i.e., warfarin or NOACs).

But even the black patients with prescriptions had a somewhat higher risk of stroke than their white counterparts. (Note: The study authors did not examine whether patients took the medicines, only if they had been given a prescription.)

Editor’s Comments

It’s well reported that African Americans have a lower risk of developing A-Fib as compared to Caucasians. But until now, there was little data on the additional risks that come with A-Fib for each race.

The new findings build on previous studies examining the impact of race on the risk of developing atrial fibrillation.

More Facts About Strokes in African Americans: On his website, Dr. Greg Hall, who specializes in urban health and the clinical care of African Americans shared these sobering facts about strokes in African Americans:

“Most strokes in African Americans occur due to high blood pressure, and a much higher number of African Americans have uncontrolled blood pressure.

A quarter of all strokes occur in the presence of atrial fibrillation (a fib). And while representing 13 percent of the US population, African Americans experience almost twice that percentage of all strokes (26%).

Strokes are worse in Blacks. And when a stroke occurs, African Americans have them earlier in life and present with more severe and disabling conditions. “

To learn more, see Dr. Hall’s post: Atrial Fibrillation in African Americans

A-Fib Stroke Risk Greater for Blacks: This is obviously a very important study for black patients. If you’re African American, you have less chance of developing A-Fib. 

But if you do develop A-Fib, your stroke risk is much greater than for Caucasians. As Dr. Hall points out, African Americans experience almost twice the percentage of all strokes (26%) while making up only 13% of the U.S. population.

“Silent” A-Fib Stroke Risk Greater for Blacks: An even more disturbing fact is that in this study, half of the strokes occurred before an African American patient was diagnosed with A-Fib. Silent A-Fib is a danger for all A-Fib patients, but the stroke risk was nearly one-third higher in black patients.

Blacks Urgently Need Monitoring for Silent A-Fib: Most strokes in African Americans occur because of high blood pressure which is more prevalent in blacks. But from a public health aspect, it’s even more important to test black patients for silent A-Fib. Monitoring for silent A-Fib needs to become Standard Operating Procedure for blacks reaching middle age.

If you are African American, you should be monitored or get yourself a DIY A-Fib monitor to make sure you don’t have silent A-Fib.

(For recommended DIY heart monitors, see my article, Do-It-Yourself ECG: A Review of Consumer Handheld ECG Monitors.) 

 

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