Which Way to the Summit?

A 57-year-old man presented with palpitations and dizziness for one day. He reported a history of similar short-lasting, self-limiting episodes in the past. Evaluation showed a hemodynamically stable, ongoing monomorphic ventricular tachycardia (VT) with positive concordance in the precordial leads and inferior axis. A structurally normal heart was seen on echocardiography. The VT was cardioverted to normal sinus rhythm with a biphasic 100-J direct-conversion shock under mild sedation, only to spontaneously start over again. In view of the patient's structurally normal heart, a previous history of similar complaints in the past, and no obvious trigger including ischemia for VT, he subsequently underwent an electrophysiology study (EPS).