Polymorphic ventricular tachycardia due to change in pacemaker programming

Introduction Bradycardia is a known risk factor for QT prolongation and polymorphic ventricular tachycardia (polymorphic VT). With the widespread use of pacemakers, it is important to pay attention to different pacing modes while programming pacemakers to avoid bradycardia. We present a case of bradycardia-induced polymorphic VT that occurred after a VDD pacemaker was replaced with a VVIR pacemaker. The lower pacing rate of the new VVIR pacemaker was set at 50 beats per minute (bpm), similar to the old VDD pacemaker. With the absence of atrial tracking in the VVI mode, the patient was paced at the lower pacing rate. The resultant bradycardia caused significant QT prolongation with subsequent polymorphic VT. Increasing the lower pacing rate corrected the QT prolongation and resolved the polymorphic VT.