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

BACKGROUND

The electrophysiology algorithm for localizing left or right origins of outflow tract ventricular arrhythmias (OT-VAs) with lead V 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 V transition.

METHODS

We measured lead I R-wave amplitude in 82 OT-VA patients with lead V 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 V S/V R index, transitional zone (TZ) index, and V 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 V S/V R index, TZ index, and V 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 V transition.