VEin of MArshall Ethanolization Vs Extended Pulmonary Vein PULSEd Field Ablation After Failed PVI for Persistent AF

The goal of this clinical trial is to compare two ablation techniques to treat patients with persistent atrial fibrillation (irregular and often very rapid heart rhythm). An ablation is a procedure during which some scars are made on the inside of the heart to break up the electrical signals that cause the irregular heartbeat. In this trial researchers will compare a new technique, which uses tiny electric shocks to make the scars, to the standard technique, which uses heat. The main question the trial aims to answer is: • Does the new technique work as well as the standard technique to prevent the irregular heartbeat from returning within one year of the procedure? Participants will: * Undergo an ablation with either the new or the standard technique * Visit the hospital 1, 3, 6, 9 and 12 months after the procedure for a check-up * Wear a device to register their heart rhythm for 24 hours before the 3 month visit and for 72 hours before the 6, 9 and 12 month visit * Record their heart rhythm at home every week * Complete a questionnaire 3, 6, 9 and 12 months after the procedure