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

BACKGROUND

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.

OBJECTIVE

The purpose of this study was to develop a more accurate electrocardiographic (ECG) criterion for differentiating between left and right OT-VA origins.

METHODS

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 (QRS) 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 (VS/VR index, V transition ratio, and transition zone index) in the validation cohort with 107 patients (RVOT 75; LVOT 32).

RESULTS

QRS of identical precordial leads were significantly greater in the LVOT group than the RVOT group (P <.05). In the development cohort, QRS of V (VQRS) 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, VQRS ≥0.52 mV outperformed previous criteria in predictive performance (accuracy 90.7%; sensitivity 84.4%; specificity 93.3%). This advantage of VQRS over previous criteria also held true for subgroups of transition zone index = 0 and V R/S transition.

CONCLUSION

VQRS is a novel and accurate ECG criterion to predict OT-VA origin that outperforms previous criteria.