Reverse-Type Left Posterior Fascicular Ventricular Tachycardia: A New Electrocardiographic Entity.

Objectives: This study sought to demonstrate a new type of verapamil-sensitive fascicular ventricular tachycardia (VT) with a reverse circuit.

Background: Left posterior fascicular ventricular tachycardia (LPFVT) is the most common form of verapamil-sensitive fascicular VT. Reverse-type LPFVT has not been reported.

Methods: We searched for a reverse-type LPFVT among 242 patients with verapamil-sensitive VT from February 2006 to September 2019.

Results: Three patients had a reverse-type LPFVT (cycle lengths: 340, 360, and 340 ms). QRS configuration during VT was narrow (140, 150, and 140 ms) and exhibited rSr' morphology in V with an early precordial transition and inferior axis. Two of 3 patients had common-type LPFVT. During reverse-type LPFVT, the earliest ventricular activation was the left superior middle septum. Fragmented Purkinje potentials (P1) buried within the local ventricular electrogram were recorded with an activation sequence from the apex to the base and were linked to the subsequent left ventricular septal activation. After radiofrequency catheter ablation at P1 during LPFVT, the reverse-type LPFVT also became noninducible. In 1 patient with only the reverse-type LPFVT, radiofrequency catheter ablation at the earliest LV activation site suppressed VT. These findings suggest that this new type of verapamil-sensitive fascicular VT shares a re-entrant circuit with a reverse direction of common LPFVT with an intramural exit site at the superior middle septum.

Conclusions: Reverse-type LPFVT can occur. If common LPFVT exists, diastolic P1 during LPFVT can be a common target of ablation. If only reverse-LPFVT is inducible, the earliest ventricular activation site can be a target.