Materials and Methods
ORTs undergoing electrophysiology (EP) study in our center between January 2017 and January 2022 were reviewed. ORT relying on aberrancy were selected using the following criteria: (1) Multiple episodes of ORT with aberrant conduction in ECG from emergency room or EP study; (2) No baseline BBB during sinus rhythm; (3) Absence of narrow QRS form during tachycardia unless isoproterenol used; (4) Restoration of bundle branch conduction giving rise to tachycardia termination or circuit alteration. ECGs and intracardiac tracings during study were carefully examined. The study was approved by the ethics committee of Huashan Hospital Fudan University.