Electrophysiological and electrocardiographic predictors of ventricular arrhythmias originating from the left ventricular outflow tract within and below the coronary sinus cusps.

Aims: Ventricular arrhythmias (VAs) from the left ventricular outflow tract (LVOT) can originate from within or below the aortic sinus of valsalva (ASV). Mapping and ablation below the ASV is challenging and there are limited data predicting VA origins using electrocardiographic and electrophysiological features.

Methods: Thirty-four patients (56.7 ± 15.2 years; 19 males) with symptomatic VAs were analyzed. VA origins were determined by successful ablation. Patients were classified into 2 groups (group 1, VAs within the ASV; group 2, VAs below the ASV). Local activation and QRS morphology were compared between these 2 groups.

Results: Twelve patients were classified as group 1 and 22 as group 2. Presystolic potentials (PPs) during VAs were present in 11 patients (91 %) in group 1 and 3 (13 %) in group 2. S-wave amplitude and duration in lead I were lower and shorter in group 1 vs. group 2, respectively. Q-wave aVL/aVR ratio (Q-aVL/aVR) was smaller in group 1 vs. group 2. No group 1 patients had Q-aVL/aVR >1.45. PPs in the ASV was the strongest independent predictor for VAs originating within the ASV (OR: 30.003, P = 0.006).

Conclusion: Deeper and longer S-waves in lead I and Q-aVL/aVR >1.45 suggest VAs originating below the ASV. Local PPs strongly suggest an origin within the ASV. ECG characteristics combined with local PPs can be a practical guide for ablating LVOT-VAs.