Patients undergoing first time cardiac surgery will undergo rapid atrial pacing prior to initiation of cardiopulmonary bypass to screen for AF inducibility. Patients with inducible AF will be randomized to prophylactic amiodarone treatment versus no treatment. Patients who are not inducible to AF will be treated with standard post-operative care. Patients will be monitored post-operatively to explore the value of intraoperative inducibility of AF to predict POAF and to evaluate whether the combination of intraoperative inducibility and precision amiodarone therapy is effective at reducing the incidence of POAF