Researchers say using opioids such as hydrocodone can increase your risk of developing an irregular heartbeat, which can lead to heart attack. Learn more.

If you have atrial fibrillation, your risk of suffering the most common type of heart attack goes up.

And if you take an opioid such as hydrocodone, you’re increasing your risk of developing an irregular heartbeat in the first place.

That’s the conclusion of two new studies released today.

Get The Facts: Atrial Fibrillation By The Numbers »

In the first, researchers refined the results of a 2013 study of heart rhythm disorders. The team, led by Dr. Elsayed Z. Soliman of Wake Forest Baptist Medical Center, concluded atrial fibrillation raises the risk of non-ST segment elevation myocardial infarction (NSTEMI).

That’s the more common but less serious of the two types of heart attacks. It occurs when a blood clot partly clogs an artery leading to the heart causing a portion of the heart muscle that gets blood from that artery to be damaged.

Researchers reviewed the records of 14,462 people who took part in an Atherosclerosis Risk in Communities study that looked at atrial fibrillation between 1987 and 2010.

Soliman and his fellow researchers concluded an irregular heartbeat increased the overall risk of a heart attack by 63 percent, with a higher rate of increase for women. They also found that risk is limited to the NSTEMI type of heart attack.

Having atrial fibrillation, the researchers said, did not increase the risk of the less common but more serious type of heart attack known as ST segment elevation myocardial infarction (STEMI).

“These results have important implications for management of the risk of heart attack in people with atrial fibrillation,” Soliman said. “For example, blood thinners that are commonly prescribed to people with AFib to prevent stroke may not be as effective in preventing heart attacks in this population.”

The results were published in the American Heart Association journal Circulation.

Read More: What Are The Triggers For Atrial Fibrillation »

In the second study, researchers looked at 24,632 people who participated in an earlier, separate study on atrial fibrillation.

More than 7 percent of the volunteers reported using opioids. The most common was hydrocodone, followed by propoxyphene and tramadol.

More than 8 percent were diagnosed with atrial fibrillation.

The researchers discovered that about 12 percent of the opioid users had atrial fibrillation, compared to just 7 percent of the nonusers.

The researchers adjusted the results to take substance abuse into consideration, but said they still found a significant difference between users and nonusers. That difference remained when the researchers also took out the users of propoxyphene, due to its “cardiotoxic effects.”

The researchers noted an increase during the past two decades in both opioid use and cases of atrial fibrillation in the United States. They said the increases may be connected and recommended more research. 

The results of their study were published in The Journal of the American Medical Association (JAMA).

Read More: Treatment Options For Atrial Fibrillation »