Black patients in the U.S. with atrial fibrillation — an irregular heart rhythm — are less likely to receive the medications that would help prevent stroke, the most dangerous outcome of the condition, compared to whites and Hispanics, according to a new study.

The study involved more than 12,000 patients with atrial fibrillation, often called AFib or AF. When researchers took socioeconomic factors into account, the overall difference in treatment with any kind of blood thinner between blacks and others narrowed. But black patients put on blood thinners were still less likely to receive prescriptions for one of the newer, more effective medications.

“We found that African American patients were much less likely to receive the newer class of anticoagulant medications than whites, even after controlling for socioeconomic factors, such as income, education and insurance type,” said Dr. Utibe Essien of the University of Pittsburgh School of Medicine and core investigator at the Center for Health Equity and Research Promotion at the VA Pittsburgh Healthcare System in Pennsylvania.

The data were collected between 2013 and 2016 from participants in a multi-site trial assessing outcomes of AFib treatment. All of the patients in the current analysis had been diagnosed with AFib, and 11,100 identified themselves as white, 646 as black and 671 as Hispanic.

After accounting for clinical and sociodemographic factors, the researchers found that black patients were 25 percent less likely to receive any oral anticoagulant drugs compared to white and Hispanic counterparts and 37 percent less likely to receive the newer medications that are safer and easier to use, according to the results published in JAMA Cardiology.

The biggest difference between the older and newer drugs, Essien said, is that the newer ones are easier to use. With the older drugs, patients need to get their blood tested at regular intervals, so the dose can be modified if needed, he explained.

The researchers also determined that for black patients, the blood-thinning effect of the older medication warfarin was less likely to end up in the right range, which would be another factor suggesting that the newer drugs might be a better choice for these patients.

“We have decades of data showing that (anticoagulant therapy) is the most important way to prevent stroke,” Essien said, adding that studies have shown black patients are at higher risk of stroke than whites.

The analysis wasn’t designed to determine why individual patients and their doctors chose the treatments they did, and it didn’t examine whether the medications prescribed affected outcomes like stroke.

What’s particularly striking about the findings is that the “data set in question is one that reflects the ideal care model,” said Dr. Clyde Yancy, chief of cardiology at Northwestern Medicine in Chicago, who wrote an editorial accompanying the study. “And after controlling for as many things as you can there is still this nagging difference that unfortunately tracks to the race of the patient.”

The new research means that all of us “finally have to acknowledge the perverse influence of subconscious bias,” said Yancy. “We should be aware of this and institute strategies that allow us to acknowledge this is operative in decision making and see ways to overcome it.”

The researchers “have advanced a theme that’s been developing over the last 25 years,” said Dr. James Glazier, a cardiologist and clinical professor of medicine at Wayne State University in Detroit, Michigan, who wasn’t involved in the study. “It’s an embarrassment to the U.S. healthcare system that depending on your race or ethnicity you don’t get the same healthcare.”

Glazier suspects there would be less disparity if there were more black cardiologists. “Specifically, 12.4 percent of the population is African American,” Glazier said. “And just over 1 percent of cardiologists identify themselves as African American. So there is a huge discrepancy. There are some very concrete things you can do. For example, you can try to get more underserved minorities to medical school.”

Wayne State has instituted a program to bring underserved minority high school kids to the university’s Harper Hospital to learn about medicine. “They learn how the operating room works and how infections are controlled, for example,” Glazier said. “And it’s paid off. Now we’re seeing the first of our young students entering medical school at Wayne State and Michigan State.”