Lead I R-wave amplitude to distinguish ventricular arrhythmias with lead V3 transition originating from the left versus right ventricular outflow tract.

ABSTRACT

BACKGROUND: The electrophysiology algorithm for localizing left or right origins of outflow tract ventricular arrhythmias (OT-VAs) with lead V3 transition still needs further investigation in clinical practice. HYPOTHESIS: Lead I R-wave amplitude is effective in distinguishing the left or right origin of OT-VAs with lead V3 transition. METHODS: We measured lead I R-wave amplitude in 82 OT-VA patients with lead V3 transition and a positive complex in lead I who underwent successful catheter ablation from the right ventricular outflow tract (RVOT) and left ventricular outflow tract (LVOT). The optimal R-wave threshold was identified, compared with the V2 S/V3 R index, transitional zone (TZ) index, and V2 transition ratio, and validated in a prospective cohort study. RESULTS: Lead I R-wave amplitude for LVOT origins was significantly higher than that for RVOT origins (0.55 ± 0.13 vs. 0.32 ± 0.15 mV; p < .001). The area under the curve (AUC) for lead I R-wave amplitude as assessed by receiver operating characteristic (ROC) analysis was 0.926, with a cutoff value of ≥0.45 predicting LVOT origin with 92.9% sensitivity and 88.2% specificity, superior to the V2 S/V3 R index, TZ index, and V2 transition ratio. VAs in the LVOT group mainly originated from the right coronary cusp (RCC) and left and right coronary cusp junction (L-RCC). In the prospective study, lead I R-wave amplitude identified the LVOT origin with 92.3% accuracy. CONCLUSION: Lead I R-wave amplitude provides a useful and simple criterion to identify RCC or L-RCC origin in OT-VAs with lead V3 transition.