Left ventricular outflow tract arrhythmias with divergent QRS morphology: mapping of different exits and ablation strategy

Ventricular arrhythmias (VAs) from the left ventricular outflow tract (LVOT) can have multiple exits exhibiting divergent ECG features.

In a series of 131 patients with VAs with LVOT origin, 10 patients presented with divergent QRS morphologies. Multisite endo- and epicardial mapping of different exit sites was performed.

The earliest ventricular activity of 23 LVOT VAs in 10 patients was detected in the endocardium of the LV in 7 patients, the aortic sinuses of Valsalva (SoV) in 3 patients, the distal coronary sinus in 6 patients, the anterior interventricular vein in 3 patients, and the posterior right ventricular outflow tract (RVOT) in 4 patients. Simultaneous elimination of two divergent QRS morphologies of LVOT VAs by ablation from a single site was achieved in 5 patients (aorto-mitral continuity in 3 patients, SoV and RVOT in each 1 patient) using a mean maximum ablation energy of 46 ± 5 W. Sequential ablation from two or three different sites, including trans-pericardial and distal coronary sinus ablation in each 2 patients, led to elimination of the divergent VA QRS morphologies in the other 5 patients. During the follow-up of 28 ± 29 months, 4 of the 10 patients had recurrence of at least one LVOT VA. A 43-year-old patient with muscular dystrophy Curschmann-Steinert had recurrence of sustained LVOT VTs and died of sudden cardiac death.

Multisite mapping of different exit sites of LVOT VAs can guide ablation of intramural foci but the recurrence rate after initially successful ablation was high.