Diabetes Drug Metformin Shows Promise in Reducing AFib Recurrence After Ablation in Overweight Patients

The diabetes medication metformin may help reduce recurrent atrial fibrillation episodes in overweight and obese patients who undergo catheter ablation procedures, according to preliminary research presented at the American Heart Association's Scientific Sessions 2025. The findings suggest that this widely available, low-cost generic drug could offer cardiovascular benefits beyond its traditional use in diabetes management.

The Metformin as an Adjunctive Therapy to Catheter Ablation of Atrial Fibrillation (META-AF) study analyzed 99 adults with AFib and obesity or overweight who did not have diabetes. All participants received catheter ablation procedures, then were randomly assigned to receive either standard care or standard care plus metformin. During the year following ablation, 78% of the metformin group remained free of AFib episodes lasting 30 seconds or more, compared to only 58% of the usual-care group.

"Treatment with metformin in people with obesity who do not have diabetes and are undergoing AFib ablation seems to lower the likelihood of recurrent AFib or atrial arrhythmias after a single procedure," said Dr. Amish Deshmukh, lead author of the study and clinical assistant professor of medicine at the University of Michigan. The research was presented at the American Heart Association's Scientific Sessions 2025 in New Orleans.

The study revealed several significant benefits for patients taking metformin. Only 6% of the metformin group required repeat ablation or electric shock to restore normal heart rhythm during AFib episodes, compared to 16% in the usual-care group. Additionally, the metformin group experienced less frequent AFib episodes during heart rhythm monitoring (8% versus 16%), and fewer patients required antiarrhythmia medications after ablation (8% versus 18%).

Notably, weight changes were minimal across all participants, suggesting that metformin's benefits in reducing AFib recurrence may not be primarily due to weight loss. This finding aligns with previous research showing that metformin can directly affect heart cells and reduce irregular heart rhythms in laboratory models.

The study population consisted of adults with an average age of 63 years, with 70% categorized as obese and the remainder as overweight. All participants were taking blood thinners to reduce stroke risk, and the ablation procedures targeted the pulmonary veins, known to be common trigger areas for AFib. According to the American Heart Association's 2025 Heart Disease and Stroke Statistics, AFib currently affects more than 6 million people in the U.S.

While most participants tolerated metformin well, a significant number (12 of 49) stopped taking the medication due to side effects or because they felt better and didn't want to add another medication to their regimen. This highlights potential challenges for long-term adherence in clinical practice.

The findings raise important questions about whether other diabetes and weight loss medications, such as GLP-1 receptor agonists, might offer similar benefits for AFib patients without diabetes. Dr. Deshmukh suggested that "a study comparing various medications would be valuable to confirm our findings and also to address questions about tolerability, the feasibility of long-term use and costs."

This research is particularly significant because obesity is a common risk factor for AFib, and recurrent episodes are more frequent in overweight and obese patients following catheter ablation. The study's limitations include its relatively small size and single-center design, meaning the findings may not be generalizable to different populations or medical centers with varying ablation techniques.

As atrial fibrillation continues to affect millions of Americans and represents the most common heart rhythm disorder, finding effective, affordable adjunctive treatments could substantially improve patient outcomes and reduce healthcare costs. The potential repurposing of metformin for AFib management represents an important development in cardiovascular care that warrants further investigation through larger, multi-center trials.