People with atrial fibrillation (AF) and obesity may have fewer episodes of AF after catheter ablation treatment if they take the diabetes medication metformin in addition to standard care, according to preliminary, late-breaking science presented at the 2025 American Heart Association (AHA) Scientific Sessions (7–10 November, New Orleans, USA).
“Lifestyle and risk factor modification efforts are essential to treating AF and, according to the results of our study, could be aided by taking metformin,” said Amish Deshmukh (University of Michigan, Ann Arbor, USA), lead author of the study.
Metformin is a widely prescribed generic medication that helps control blood sugar levels, primarily in people with Type 2 diabetes. It is often used as an initial treatment due to its effectiveness, long history of use and relatively low cost.
In previous research on adults with diabetes and obesity, those taking metformin to manage blood sugar and weight have shown a lower risk of AF as compared to other antidiabetic agents. In studies of laboratory models, metformin has also directly affected heart cells and reduced irregular heart rhythms, leading to researchers wanting to find out if the drug can help lower the chances of AF returning in people treated for the condition who are overweight or obese.
The META-AF study analysed 99 adults with AF—who were obese or overweight—to determine whether adding metformin to standard care after a catheter ablation procedure would be beneficial. All participants received ablation and were then randomly selected to receive either usual care, including lifestyle education about physical activity, healthy eating, sleep and management of other medical conditions, or usual care plus metformin.
During the yearlong period after ablation, the analysis found that:
- Some 78% of patients in the metformin group versus 58% in the usual care group had no episodes of AF lasting 30 seconds or more
- The metformin group had fewer patients who needed a repeat ablation or electric shock to restore a normal heart rhythm during an AF episode (6% vs 16%, respectively)
- The metformin group had less frequent AF episodes during heart rhythm monitoring compared to the usual care group (8% vs 16%, respectively)
- Antiarrhythmic medications were used after ablation in 8% of patients in the metformin group and 18% in the usual care group
- Weight changes were minimal in all participants, consistent with prior studies of metformin use in people without diabetes
“Treatment with metformin in people with obesity who do not have diabetes and are undergoing AF ablation seems to lower the likelihood of recurrent AF or atrial arrhythmias after a single procedure,” Deshmukh added. “While most people tolerated the medication well, a significant number stopped taking it due to side-effects, or because they felt well and did not want to add another medication to their regimen.”
According to the META-AF researchers, these results raise the question of whether other medications for diabetes and weight loss, such as GLP-1 receptor agonists, may have similar benefits and side-effects in adults without diabetes who have AF and are obese.
“I would suggest conducting a larger study to investigate metformin and other diabetes treatments,” Deshmukh commented. “We know that many of these medications offer cardiovascular benefits, and we are starting to gain a better understanding of how they might specifically benefit patients with arrhythmias. 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.”
Limitations to this study include it being small and conducted at one medical centre, with researchers also noting that the findings may not be generalisable to centres with different populations or different techniques for performing catheter ablation.
