The QRS-right ventricular apex interval as a cut-off value to differentiate the origin of outflow tract premature ventricular complexes.

BACKGROUND

Many electrocardiography (ECG) criteria have been proposed for the localization of outflow tract premature ventricular contractions (PVCs); however, in some cases, it is difficult to accurately localize the origin of PVCs using the surface ECG. The authors aimed to study the QRS-right ventricular apex (RVA) interval measured during electrophysiological study and its role in the differentiation between different sites of origin of outflow tract PVCs.

METHODS

The study included 90 patients (81 females, mean age 37.20 ± 7.87) referred for outflow tract PVC ablation. The authors measured the interval from the onset of the earliest QRS complex of the PVCs to the distal RVA intracardiac signal (the QRS-RVA interval) during the electrophysiological study and correlated this interval with the origin of outflow tract PVCs as identified by successful ablation during the procedure.

RESULTS

The QRS-RVA interval was significantly longer in PVCs originating from the left ventricular outflow tract (LVOT) compared to the right ventricular outflow tract (RVOT) (67.33 ± 7.56 for LVOT PVCs vs. 37.11 ± 4.34 for RVOT PVCs, p < 0.001). Receiver operating characteristic (ROC) analysis showed that a QRS-RVA interval ≥ 48 ms predicted an LVOT origin of PVCs. A shorter interval was noted in PVCs originating from the RVOT free wall rather than the septal RVOT wall, and a shorter interval was also noted in LVOT PVCs originating from the right coronary cusp as compared to other LVOT PVCs, although these differences did not reach statistical significance.

CONCLUSION

Measuring the QRS-RVA interval is a simple and accurate method for differentiating the origin of outflow tract PVCs during an electrophysiological study. A QRS-RVA interval ≥ 48 ms predicts an LVOT origin of PVCs rather than an RVOT origin.