The DefiPace Study

Phase A Approximately 150 consecutive patients undergoing elective cardiac surgery (bypass and / or valve surgery) * Data regarding standard of care post-operative pacing and treatment of POAF, if applicable, will be collected from time of surgery until discharge * No use of an external bi-atrial pacing device * No use of Defipace * In-hospital data will be collected for all patients * Patients that developed POAF (n=50) will be followed-up with a phone call 30 days after surgery. Phase B Approximately 300 consecutive patients undergoing elective cardiac surgery (bypass and / or valve surgery) with planned TMA implantation * In-hospital data will be collected for all patients * Use of the DefiPace system for the treatment (low-energy cardioversion) and post-operative prevention (bi-atrial pacing) of POAF will be documented (n=100). These patients will be followed-up with a phone call 30 days after surgery