Abstract
A 69-year-old man, who had undergone surgery for mitral and tricuspid regurgitation with the Maze procedure for paroxysmal atrial fibrillation, was admitted with an episode of syncope due to sick sinus syndrome. Three days after implantation of a dual-chamber pacemaker (Accent MRI™, St. Jude Medical Inc.,), ventricular pacing on T-wave was recorded multiple times. St. Jude Medical Inc. pacemakers have a unique additional algorithm, called premature ventricular contraction response, related to preventing pacemaker-mediated tachycardia. This algorithm was determined to be a cause of ventricular pacing on T-wave. We report the limitations and potential adverse effects of such automated algorithms.