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To evaluate the validity of lead aVL for identifying idiopathic outflow tract premature ventricular contractions (IOT-PVCs) originating from aortic sinus cusp (ASC).
This study retrospectively enrolled 65 successive patients (mean age 42.3 ± 15.6 years, 21 male) of IOT-PVCs in which lead V1 presented with an rS QRS pattern at Second Xiangya Hospital of Central South University between February 2015 and February 2016. None of the patients had structural heart disease by physical examination and echocardiography. All patients underwent catheter ablation procedures and then a series of parameters of QRS waveform amplitudes from the surface 12-lead electrocardiogram (ECG) tracing were measured manually and analyzed.
16 patients (24.6%) were from ASC and 49 patients (75.4%) were from right ventricular outflow tract (RVOT). There were no significant differences in baseline characteristics between the 2 groups of PVCs origin, except there were more males in the ASC group than in the RVOT group (10 in 16 patients vs 11 in 49 patients, P=0.003). Four variables of parameters of QRS waveform amplitudes with statistical difference between two groups and the four relatively larger AUC values, included the lead aVL S index which equals lead aVL S wave amplitude in PVCs minus that in sinus rhythm, the lead V1 R/R+S wave amplitude ratio (in PVCs), the lead aVL S wave amplitude (in PVCs) and the lead V1 R wave amplitude (in PVCs). The AUCs and 95% CIs of the four variables used for identifying the origin in the ASC were 0.859(0.741-0.977), 0.853(0.762-0.943), 0.837(0.718-0.957) and 0.828(0.726-0.930), and the cut-offs were 0.6mV, 0.20, 0.7mV and 0.25mV respectively. Among them, the lead aVL S index was selected to develop the new method for identifying ASC originating PVCs because of the largest AUC value. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 81.3%, 89.8%, 72.2%, 93.6% and 87.7%, respectively.
For rS QRS pattern in lead V1 of IOT-PVCs, lead aVL S index > 0.6mV could be applied to identifying ASC originating PVCs.