The goal of this clinical trial is to learn if drug dapagliflozin, a sodium-glucose transport-2 inhibitor, works to treat atrial fibrillation in adults. The main question it aims to answer is: • Does the drug dapagliflozin reduce the recurrence rate of atrial fibrillation? Researchers will compare drug dapagliflozin to standard therapy to see if drug dapagliflozin reduce the recurrence of atrial fibrillation. Persons with atrial fibrillation who are planned for an electric cardioversion will: * Take the drug dapagliflozin, or no drug, once a day for a maximum of 56 days * Undergo a planned electric cardioversion of the atrial fibrillation * Record the rhythm with a hand-held device that transmits the signal to researchers during the study period, but no longer than for 56 days