Here’s a surprising revelation: a drug commonly used for diabetes might hold the key to reducing atrial arrhythmia recurrences in overweight or obese patients undergoing catheter ablation—even if they don’t have diabetes. But here’s where it gets controversial: the benefits aren’t fully explained by weight loss or improved blood sugar control, leaving researchers puzzled yet excited about its potential. The META-AF trial, presented at the American Heart Association (AHA) 2025 Scientific Sessions, found that patients with a body mass index (BMI) of 25 kg/m² or higher who took metformin for six weeks before their procedure had a significantly lower risk of atrial arrhythmia recurrence and reduced atrial fibrillation (AF) burden after one year.
And this is the part most people miss: while metformin is known for its role in managing diabetes, its effects in this context seem to go beyond blood sugar regulation. Investigator Amrish Deshmukh, MD, from the University of Michigan, suggests that the drug may directly impact cardiac cells, potentially preventing AF. This is particularly intriguing because AF is notoriously linked to higher BMI, with overweight individuals facing not only a greater risk of developing AF but also its progression to more severe forms.
The META-AF trial enrolled 117 patients with persistent or paroxysmal AF and overweight or obesity, randomizing them to receive either standard care (lifestyle education) or standard care plus metformin. Lifestyle education focused on weight loss, exercise, sleep apnea management, and reducing tobacco and alcohol use. Metformin was adjusted to the highest tolerable dose, and all participants used a handheld ECG device to monitor their heart rhythm.
The results were striking: atrial arrhythmia recurrence lasting over 30 seconds between 3 and 12 months post-ablation was halved in the metformin group compared to usual care. Freedom from recurrence was 78% with metformin versus 58% with usual care. AF burden, another key metric, was also significantly lower in the metformin group. Interestingly, both groups lost weight and saw symptom improvements, but metformin’s advantages persisted despite similar HbA1c levels in both arms.
Here’s the controversial question: Could metformin’s role extend beyond diabetes management to become a game-changer in AF treatment? Discussant Gregory G. Schwartz, MD, PhD, highlights metformin’s long history—dating back to its use as an herbal remedy in the 17th century—and its mechanism of action, which involves stabilizing cellular energy metabolism. In AF, where atrial energy metabolism is disrupted, metformin’s ability to sustain this process under stress could explain its anti-arrhythmic effects.
While the META-AF trial was a single-center, open-label study that didn’t assess long-term metformin use, its findings are compelling enough to warrant larger, randomized trials. What do you think? Is metformin’s potential in AF treatment a breakthrough, or is it too early to tell? Share your thoughts in the comments—this debate is far from over!
