African-Americans are less likely than white people to get the newest stroke-preventing medicines for atrial fibrillation, a recent study found.

Atrial fibrillation, often called A-fib, is the quivering or irregular heartbeat that increases the risk for stroke and other heart problems. The standard treatment is oral anticoagulants, or blood thinners, to prevent blood clots.

The study, in JAMA Cardiology, included 11,100 whites, 646 blacks and 671 Hispanic patients diagnosed with A-fib. After adjusting for the clinical features and severity of the condition, the study’s authors found that blacks were 25 percent less likely than whites to receive any oral anticoagulant and 37 percent less likely to receive the newer, and in many cases more effective, direct-acting oral anticoagulants. There was no difference between whites and Hispanics.

When they further adjusted for socioeconomic factors, blacks were still 27 percent less likely to receive the newer anticoagulants.

The lead author, Dr. Utibe R. Essien, an assistant professor of medicine at the University of Pittsburgh, said that questions of adherence and expense may enter a provider’s mind in choosing a medicine, but unconscious bias is also an issue.

“We may have certain assumptions about patients that are irrelevant to health care,” he said, “and then fail to offer them the full breadth of medical treatment.”

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