236 Modified High Precordial Lead R-Wave Deflection Interval Accurately Predicts Left and Right-Sided Idiopathic Outflow Tract Ventricular Arrhythmias

Abstract

Electrocardiogram (ECG) prediction algorithms for outflow tract ventricular arrhythmias (OTVA) using standard precordial lead configuration localise OTVA with variable accuracy. We evaluated if modifying ECG precordial leads to a higher intercostal position improved the accuracy of OTVA localisation. Patients undergoing OTVA catheter ablation were prospectively enrolled. Multiple indices were measured to develop an algorithm that differentiated RVOT and LVOT with high accuracy: the modified lead R-wave deflection interval (RWDI). The accuracy of the RWDI was compared to all ECG algorithms using a standard precordial ECG position. Finally, prospective validation of the modified lead RWDI was performed. 40 patients (31 females, mean age 51±18 years) had a successful catheter ablation for OTVA (RVOT 60%, LVOT 40%). The modified lead RWDI was significantly shorter in the RVOT group compared to the LVOT group (16.7±13.4ms vs 66.8±14.4ms, p<0.0005). Using a RWDI <40ms to predict a RVOT focus, the sensitivity and specificity of the modified lead RWDI were both 100% and area under the receiver operator characteristic curve was 1. This was superior to all previously published algorithms. In the validation cohort (n=16 patients), the sensitivity and specificity of the modified lead RWDI was 88% and 75%, respectively. In 2 patients with a failed RVOT ablation, the modified lead RWDI was >40ms, indicating a LVOT focus. The modified lead RWDI is a simple, easily interpretable algorithm that can differentiate a right or left-sided origin of OTVA with high accuracy.