All eligible and consenting patients will undergo elective electrical cardioversion for atrial fibrillation (AF) using the Ottawa AF protocol.The fact that the physician follows the protocol makes this experimental. Aside from following the protocol, subjects will receive standard care before, during and after the procedure. Outcomes of the procedure and clinical features know to affect cardioversion efficacy will be collected. These will be compared to a group of 500 previous patients who underwent elective electrical cardioversion for AF at the Heart Institute.