Metformin May Help Prevent Recurrence of Atrial Fibrillation After Ablation in Adults with Obesity

Key Takeaways: 

• Adults with obesity who took metformin after AFib ablation had fewer recurrences of atrial fibrillation compared with those receiving standard care alone.
  
• 78% of participants receiving metformin remained free of AFib episodes lasting 30 seconds or more, compared with 58% in the standard care group.
  
• Researchers suggest further large-scale studies are needed to confirm whether diabetes medications such as metformin or GLP-1 receptor agonists could support heart rhythm stability in people with obesity who do not have diabetes.
  
  

Metformin shows promise beyond diabetes treatment

People with atrial fibrillation (AFib) and obesity may experience fewer episodes of irregular heart rhythm after undergoing ablation if they take the diabetes medication metformin in addition to standard care, according to a preliminary presentation of late-breaking science at the American Heart Association’s (AHA) Scientific Sessions 2025, held from 7 to 10 November in New Orleans. The annual meeting is a leading international forum for sharing new research and clinical advances in cardiovascular medicine.

“Lifestyle and risk factor modification efforts are essential to treating AFib and, according to the results of our study, could be aided by taking metformin,” said Dr Amish Deshmukh, lead author and clinical assistant professor of medicine at the University of Michigan in Ann Arbor.

AFib, characterised by an irregular and often rapid heartbeat, is the most common form of heart rhythm disorder. According to the AHA, it can lead to blood clots, stroke, heart failure, or other cardiovascular complications.

Metformin, a long-established and low-cost generic medication, helps regulate blood glucose levels and is most often prescribed to people with Type 2 diabetes. It is widely regarded as a first-line treatment due to its safety, affordability, and efficacy.

Exploring metformin’s role in reducing AFib recurrence

Previous research has indicated that people with diabetes and obesity who take metformin tend to have a lower risk of developing AFib compared with those using other antidiabetic medications. In laboratory studies, metformin has shown direct effects on cardiac cells, including the reduction of abnormal heart rhythms. Building on this evidence, researchers sought to determine whether metformin could help reduce the recurrence of AFib in people with obesity or overweight following catheter ablation.

The Metformin as an Adjunctive Therapy to Catheter Ablation of Atrial Fibrillation (META-AF) study enrolled 99 adults with AFib who were either overweight or obese. All participants underwent catheter ablation – a procedure that targets and removes small areas of heart tissue responsible for irregular electrical activity – and were then randomly assigned to receive either standard care alone or standard care plus metformin.

Standard care included lifestyle education focused on physical activity, nutrition, sleep, and management of comorbidities. Participants in the metformin group received the medication in addition to these measures.

Key findings: Fewer AFib episodes with metformin

Over the 12 months following ablation, the analysis revealed:

• 78% of those taking metformin experienced no AFib episodes lasting 30 seconds or longer, compared with 58% of those receiving usual care.
  
• 6% of participants in the metformin group required a repeat ablation or electric cardioversion (a procedure to restore normal rhythm) versus 16% in the usual care group.
  
• 8% of participants in the metformin group had recurrent AFib during rhythm monitoring, compared with 16% in the usual care group.
  
• Antiarrhythmic medication was required by 8% of participants in the metformin group versus 18% in usual care.
  
• Weight changes were minimal across both groups, consistent with previous findings that metformin produces little or no weight reduction in people without diabetes.
  

“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,” Dr Deshmukh said. “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.”

Could other diabetes medications offer similar benefits?

The findings raise further questions about whether other diabetes or weight management drugs – particularly GLP-1 receptor agonists – may also help prevent AFib recurrence in people with obesity who do not have diabetes.

Obesity is a well-established risk factor for AFib. People living with obesity often experience more frequent or recurrent episodes of the condition following catheter ablation. According to the American Heart Association’s 2025 Heart Disease and Stroke Statistics, more than six million people in the United States currently live with AFib.

“I would suggest conducting a larger study to investigate metformin and other diabetes treatments,” Dr Deshmukh added. “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.”

Study design and limitations

The META-AF study was conducted at the University of Michigan between 2021 and 2025. It involved 99 adults with an average age of 63 years; 70% were men, and most were white. Among participants, 70% were classified as obese and the remainder as overweight. About 22% had previously undergone ablation, and 46% experienced AFib that stopped spontaneously within a week.

Participants with Type 1 or Type 2 diabetes were excluded, although 40% met criteria for prediabetes (HbA1c between 5.7% and 6.4%). Individuals taking diabetes medications or those for whom metformin posed risks were also excluded.

All participants received anticoagulant therapy to reduce the risk of stroke. The ablation targeted pulmonary vein tissue, a common source of AFib triggers.

The study was open-label, meaning participants knew which treatment they were receiving. Forty-nine participants were assigned to the metformin group and fifty to standard care. After a three-month healing period post-ablation, and once the metformin dose was gradually increased to its maximum, participants were monitored for recurrent AFib lasting at least 30 seconds. Researchers measured the AFib burden – the proportion of time spent in AFib – at three months and twelve months using clinical monitoring data, handheld devices, pacemakers, and defibrillators.

A notable limitation was participant withdrawal: 12 of the 49 people assigned to metformin discontinued treatment due to side effects or because they felt improved and preferred to stop the medication. The small sample size and single-centre design also limit generalisability to other populations or ablation techniques.

Disclosures and context

The study’s co-authors, funding, and disclosures are listed in the abstract presented at the AHA meeting.

The AHA emphasises that statements and conclusions from conference presentations reflect only the authors’ views and do not necessarily represent official policy or position. Abstracts presented at the Association’s scientific sessions are reviewed for scientific merit but are not peer-reviewed publications. Therefore, these findings are considered preliminary until published in a peer-reviewed journal.

The Association notes that over 85% of its funding derives from non-corporate sources, including individual donations, foundations, estates, investments, and educational material sales. Corporate donations are accepted under strict policies that prevent any influence on scientific content or policy positions.