Patients with cardiac implantable electronic devices are at additional risk for arrhythmias while undergoing surgical procedures. In this case report, we present a patient with a dual chamber implantable cardioverter-defibrillator who developed intraoperative pacemaker-mediated tachycardia causing significant hemodynamic instability. Management of this arrhythmia can be particularly challenging, because standard application of a magnet does not affect the pacing functions of an implantable cardioverter-defibrillator. Awareness by the anesthesiologist and timely coordination with the cardiac electrophysiology team helped to optimize care for this patient.