Amplitude of QRS complex within initial 40 ms in V2 (V2QRSi40): Novel electrocardiographic criterion for predicting accurate localization of outflow tract ventricular arrhythmia origin

Abstract

The initial depolarization vector of outflow tract (OT) ventricular arrhythmia (VA) varies in different origins, which may help to predict OT-VA origin more accurately. The purpose of this study was to develop a more accurate electrocardiographic (ECG) criterion for differentiating between left and right OT-VA origins. We studied 275 patients with successful ablation in the right ventricular outflow tract (RVOT) (n = 207) or left ventricular outflow tract (LVOT) (n = 68) in the development cohort. Amplitude of the QRS complex within initial 40 ms (QRSi40) in precordial leads was measured. A novel criterion for identifying OT-VA origin was developed based on the development cohort. Predictive performance of novel criterion was further validated by comparing with previous ECG criteria (V2S/V3R index, V2 transition ratio, and transition zone index) in the validation cohort with 107 patients (RVOT 75; LVOT 32). QRSi40 of identical precordial leads were significantly greater in the LVOT group than the RVOT group (P <.05). In the development cohort, QRSi40 of V2 (V2QRSi40) exhibited the greatest area under the curve of 0.950, with cutoff ≥0.52 mV predicting LVOT origin (sensitivity 86.0%; specificity 94.6%). In the validation cohort, V2QRSi40 ≥0.52 mV outperformed previous criteria in predictive performance (accuracy 90.7%; sensitivity 84.4%; specificity 93.3%). This advantage of V2QRSi40 over previous criteria also held true for subgroups of transition zone index = 0 and V3 R/S transition. V2QRSi40 is a novel and accurate ECG criterion to predict OT-VA origin that outperforms previous criteria.