(HealthDay)—Many people with the heart condition known as atrial fibrillation stop taking the blood-thinning medication that's prescribed to help prevent a stroke, a new study reveals.
Atrial fibrillation is an irregular heartbeat that causes the heart to quiver. This raises the risk of blood clots and stroke, according to the American Heart Association.
People who've had a medical procedure such as cardioversion (electrical shocks to the heart through electrodes placed on the chest) or ablation (using heat, cold or radio energy to scar heart tissue via catheter or surgery) to help manage their condition were even more likely to ditch their prescribed drugs.
"We don't know if changing the heart to a normal rhythm, by either cardioversion or ablation, always removes the risk of stroke," said study author Dr. Geoffrey Barnes, a cardiologist at the University of Michigan Frankel Cardiovascular Center.
"It's an ongoing debate, whether to continue the patient on blood thinners after a procedure," Barnes said in a university news release.
The study included more than 700 people with atrial fibrillation. All had started taking the blood thinner warfarin (brand name Coumadin) between 2011 and 2013.
In less than one year, nearly 37 percent of these people stopped taking the drug, the study found.
The research team also found that more than 54 percent of those who had cardioversion or radiofrequency ablation were off warfarin after one year.
Study participants who didn't have one of these procedures, however, were much more likely to continue warfarin therapy, the study showed. The researchers pointed out that about 30 percent of these people stopped taking the medication, which is still a sizable group not adhering to their treatment plan.
"When we took into account whether the patient had undergone a recent [atrial fibrillation] procedure, the numbers look very different," said Dr. James Froehlich, a study researcher and a Frankel Center cardiologist.
It's unclear why these patients stopped taking warfarin. The researchers speculated the drug's side effects, such as bruising, may play a role. People taking warfarin must also undergo routine blood tests. Some people may stop taking the drug to avoid having to do this, the study authors explained.
"We need to understand why they are stopping warfarin and figure out what other medications might be better adhered to in order to prevent strokes," said Froehlich.
Barnes said more study is needed to learn whether or not blood thinners are needed to prevent stroke after medical procedures. "We need more data to help us understand what the risk of stroke is after cardioversion or ablation, to inform physician decision-making and guidelines," he said.
Explore further: Medication adherence a problem in atrial fibrillation patients
The American Heart Association provides more information on atrial fibrillation.