Metformin as an Adjunctive Therapy to Catheter Ablation of Atrial Fibrillation (META-AF)

Obesity is a prevalent risk factor for recurrent atrial fibrillation (AF) after catheter ablation. Experimental and observational studies suggest that metformin may reduce the risk of AF.

To determine the effect of metformin on recurrent atrial arrhythmias after catheter ablation for AF.

In this single-center, randomized, open-label trial, patients undergoing AF ablation with body mass index (BMI) > 25 kg/m² and without diabetes were randomized (1:1) to metformin or usual care before ablation. Metformin was titrated to the maximum tolerated dose and continued for 1 year after ablation. All patients received handheld electrocardiogram monitors in addition to usual clinical monitoring. The primary endpoint was freedom from recurrent atrial arrhythmia assessed at 12 months after ablation with a 3-month blanking period.

Of 99 participants (mean age 63 ± 9.5 years, 70% men, BMI 32 ± 5.4 kg/m², A1c 5.7 ± 0.5, 46% paroxysmal, and 22% prior ablation), 49 were randomized to metformin and 50 to usual care. At 12 months, the primary endpoint occurred in 38 (78%) of the metformin group and 29 (58%) of the usual care group (HR: 0.5; 95% CI: 0.2-0.9; P = 0.04). In the year after ablation, AF burden was lower in the metformin group (IQR: 0%-0%; median 0%) compared with usual care (IQR: 0%-25%; median 0%) (P = 0.03). Antiarrhythmic drugs were used in 4 of 49 patients (8%) in the metformin group and in 9 of 50 patients (18%) in the control group after ablation.

In patients with AF, elevated BMI, and without diabetes, treatment with metformin may reduce recurrent atrial arrhythmias after ablation. These findings require confirmation in larger trials.