A new algorithm differentiate the septum originated ventricular arrhythmias from the free wall in the right ventricular outflow tract

Abstract

Background: Until now, no ventricular arrhythmias QRS axis dominated ECG algorithms was used to differentiate VT/PVCs originating from the free wall or septum in the RVOT. In this study, we described new ECG criteria and investigated the sensitivity and specificity of them in practice. Method: Consecutive 121 patients with LBBB morphology and precordial transition lead ≥ V4 were successfully underwent mapping and ablation by contact or non-contact mapping. They were rerolled into the septum group (group A, n=95) and the free wall group (group B, n=26) according to VT/PVCs origin. We analyzed the ECG pattern with following criteria: 1) QRS axis >89°; 2) R wave amplitude III > II, and 3) A2III score including QRS axis 154.5ms (score = 1) and AVL QRS >156.5ms (score = 1). Results: Retrospective analysis that VT/PVC axis > 89° and R wave amplitude III > II predict the septum PVCs origin with 100.00% sensitivity, 93.94% specificity, and 97.78% positive prediction value. VT/PVCs A2III score ≥ 2 predicts VT/PVCs originating from the free wall in the RVOT with 80.00% sensitivity, 87.50% specificity and 84.09% positive predictor value. The new algorithm predicted VT/PVCs originating from the RVOT septum with the overall sensitivity, specificity, and positive predictor value were 91.30%, 81.48% and 97.78%. Prospective analysis in 23 patients showed that the new algorithm predicted VT/PVCs originating from the RVOT septum and free wall with overall sensitivity, specificity and positive predict value were 95.23%, 100% and 100%; 100.00%, 95.23%, and 66.67, respectively. Conclusion: VT/PVC axis > 89°, R wave amplitude III > II and A2III score ≤1 with very high sensitivity, specificity and positive prediction value for prediction VT/PVCs originating from septum origin in the RVOT.