More than 33 million people around the world have the irregular, often rapid heartbeat known as atrial fibrillation (AFib). It’s more common as you get older. But for reasons that aren’t fully understood, you’re less likely to get AFib if you’re Asian, Black, or Hispanic in America than if you’re white. One study found 2.5% of Black people had AFib compared with 7.8% of white people. Another found lower rates of AFib, but the rate in white people still was twice that in Black people (2.5% vs. 1.2%).
Researchers have also found that Black Americans have rates of AFib similar to those of Asian and Hispanic Americans. All three groups have lower rates of the condition than white Americans.
These differences exist even though Black Americans have a lot of other risk factors that doctors normally think should raise their chances of AFib. Because these facts don’t appear to make sense on the surface, experts have called this the “atrial fibrillation paradox.”
What Are the Risk Factors for Atrial Fibrillation?
Some commonly accepted conditions that make AFib more likely are:
- Heart disease
- High blood pressure
- Thyroid disease
- Other health conditions, such a diabetes, kidney disease, or lung disease
- Drinking alcohol and especially binge drinking
- Sleep apnea
- Family history
The reason doctors have been confused by lower rates of AFib in Black Americans is that this group tends to have a lot of these known risk factors. For example, about half of Black individuals have obesity. More than half of Black adults have high blood pressure. Black people also more often have diabetes compared with white people. And yet, the data show Black people don’t have AFib as much as white people do.
What does it mean? Well, if these risk factors fully explained why people get AFib, then Black people should have AFib more often than they do. So the AFib paradox suggests there are things about AFib and why it happens that doctors don’t fully understand. There could be other factors that protect Black people from AFib. But since this difference in AFib rates is mostly noted between Black and white people, it may also be that those who are Black have a normal risk level. Their rates may only appear lower because white people have a higher chance of having the condition.
Do Black Americans Really Have Less AFib?
You might wonder if Black Americans really have AFib less than those who are white. That’s a fair question because the evidence could look like that because AFib is just missed more often in Black people. It turns out researchers do have ways to look at this.
To see if Black people really do have less AFib (versus having more AFib that’s undiagnosed), researchers looked at people who had implanted pacemakers. A pacemaker makes it less likely that a doctor would miss AFib if it were there.
They looked at more than 10,000 Black individuals and more than 90,000 white individuals whose doctors hadn’t diagnosed them with AFib at the start. They followed them for more than 3.5 years. And the AFib rates really did look different. Black people in the study had a significantly lower rate of AFib than white people in the study did. The findings suggest it doesn’t just look like there’s a difference because doctors miss AFib more often when you're Black.
How Do Rates of AFib in Black Americans Compare to Other Groups?
It’s hard to know by comparing two groups whether Black people are somehow protected from AFib. It’s just as likely that white people for some reason have higher risk. To figure that out, you need to look at AFib rates in other groups of people.
It turns out researchers have looked at this, too, in a group of almost 14 million people in California who had more than 375,000 episodes of AFib. The study included people who identified as Black, white, Hispanic, and Asian. Researchers tracked their data for more than 3 years.
And how did it look? It turned out that Black, Hispanic, and Asian people all had lower chances of having AFib than white people. When you’re white, it looks like the odds of AFib are higher even when you don’t have other heart-related conditions that put you at risk. The study went on to show that the differences weren’t there as much when you compare people of different races who all have more AFib risk factors. But white people seem to get AFib more often than other groups even without any conditions that might make AFib more likely. It suggests that Black people don’t have special protection or unusually low rates of AFib. Instead, white people may have added risks for AFib that doctors don’t yet recognize or understand.
Why Does Race Seem to Affect Your Chances of Having AFib?
One reason this could happen is genetics. Some people do seem to carry genes that make them more likely to have AFib. One way to see this is that the AFib risk runs in families. If you have a parent with AFib, your chance of having it almost doubles. If you have a parent who got AFib before age 75, your risk triples. This is especially true if your family members get the condition earlier in life without having other heart problems.
The reasons that conditions run in families can be due to genetics as well as shared home environments. And some studies have pointed to changes or variants in certain genes that may influence a person’s AFib chances of AFib. One of them asked whether the higher likelihood of AFib in white people compared with Black people had to do with genetic factors.
The study looked for differences among races in the frequency of gene variants that have been linked to the likelihood of AFib. It found that white people do more often carry one AFib variant with a link to AFib. So differences in this gene variant might be part of why Black people get AFib less than white people. But it doesn’t explain all of it. The researchers estimate it explains 11%-32% of the difference.
So genetics and this gene in particular explain some of the AFib paradox. Genes might explain some of the differences in AFib risk among races. But there are still other complicated genetic and environmental reasons for differences in AFib chances and rates that scientists and doctors don’t understand.
Do Black Americans With AFib Have More Health Risks?
If you’re Black, it’s important to remember that you still could have AFib, even if it’s less likely. Even though rates are lower in Black people than in those who are white, 1 in 9 Black people will find out they have AFib before age 80. The chances of AFib go up for everyone with age. If you’re Black and don’t have AFib by age 50, your chance of getting it is 11%. This is lower than the risk white people have. But it doesn’t mean that you can’t get AFib.
Another study also suggests that if you’re Black and you do get AFib, you have a greater chance of complications. AFib comes with greater odds of a stroke. And the study found, Black people are more likely than white people to have a stroke either before or after they find out they have AFib.
So if you’re Black and have AFib, it’s a good idea to find out and get treatment to lower your chances of a stroke or other health problems. And no matter your race, if you have AFib or are worried you could have it, see a doctor.