Aortic valve artifact during ventricular tachycardia originating from the outflow tract.

A 61-year-old male with dilated cardiomyopathy underwent electrophysiological study for incessant ventricular tachycardia (VT). Although early and late diastolic potentials were recorded in the aortic sinus during VT, electrograms obtained during the sinus beat revealed two components following the QRS, suggesting that aortic valve artifacts were the cause of the prepotentials during VT. This case underscores the importance of distinguishing valve artifacts from true arrhythmogenic potentials in left ventricular outflow tract mapping.