Irregular heartbeat or atrial fibrillation (AFib) occurred more often among American Indians than among other racial and ethnic groups, said a new study. AFib affects 2.7 million people in the United States, and it is a serious disorder behind the increasing risk for stroke. The most common symptom is a fluttering heartbeat.
The study published in Circulation, the American Heart Association's premier cardiovascular research journal, examined 300,000 new cases of AFib between January 1, 2005 and December 31, 2011, in California, and found that among American Indians, new AFib cases occurred, on average, 7.5 times per year per every thousand patients. In other racial and ethnic groups, it occurred on average 6.9 times per year per every thousand patients. The higher frequency of AFib in American Indians persisted after controlling for other factors, such as age, sex, income and heart and other diseases, stated the study.
Researchers further examined the records of 16 million California residents aged 18 years or more to identify new cases of AFib and to link them to patients' self-reported race and ethnicity, with an average follow-up time being slightly more than four years. The 300,000 patients were new cases of AFib and nearly 400,000 patients were excluded due to already existing AFib.
"We were surprised to find that American Indians experienced a higher risk of atrial fibrillation compared to every other racial and ethnic group," said Gregory M. Marcus, professor of atrial fibrillation research at University of California, San Francisco. Damage to the heart from other heart diseases, such as uncontrolled high blood pressure, can increase the risk for AFib, but sometimes the root cause is unknown, he said.
But some previous studies found a higher risk among whites, even though American Indians and other minority populations may have been prone more risk factors but then the AFib research in the general population did not include American Indians.