Introduction
Outflow tract ventricular arrhythmia (OTVA) is one of the most common subgroups of idiopathic ventricular arrhythmia (VA) that typically occurs in healthy patients without any structural heart diseases. Radiofrequency catheter ablation (RFCA) is considered the curative therapy for OTVA, with a high success rate. Further, with the development of new techniques, the success rate is extremely high in experienced centers (>95%)[1]. Therefore, RFCA is suggested as Class I, level B for VA arising from the right ventricular outflow tract (RVOT), and Class IIa, level B for that arising from the left ventricular outflow tract (LVOT)[2]. Notably, it is clinically important to accurately predict OTVA origin before ablation as it reduces the risk of exposure to radiation, duration of the ablation, and the number of vascular access sites. Further, timely identification of the origin of the OTVA can improve the safety and efficacy of the ablation procedure. By accurately predicting OTVA origin, the physician can customize the ablation strategy to accurately target the arrhythmia source, thereby improving patient outcomes. Typically, VA originating in the RVOT manifests as a left bundle branch block (LBBB) configuration. In contrast, VA originating in the LVOT usually manifests either as a right bundle branch block or an LBBB. Considering the overlap between precordial transition lead and morphological similarity, it is difficult to determine the origin of OTVAs. Rapid developments in the past two decades have resulted in the identification of several ECG parameters to distinguish between the origins of RVOT and LVOT. However, the use of these mentioned parameters may lead to different predictions of the VA origin and confuse the physician. To the best of our knowledge, this is the first study to systematically investigate the accuracy of these parameters. Further, we developed the algorithm for reliably predicting OTVA origin and validated it in an additional 100 patients.