Abstract Body (Do not enter title and authors here): Background:
Accurate localization of the site of origin (SOO) of ventricular arrhythmias (VAs), including premature ventricular contractions (PVCs) and ventricular tachycardia, is essential for successful catheter ablation. Current electrocardiographic (ECG) localization algorithms have limitations in precision, particularly for complex cases.

Objective:
This study aimed to retrospectively develop and prospectively validate a novel PVC/VT-algorithm, a stepwise approach designed to enhance SOO localization accuracy and to improve ablation outcomes.

Methods:
In this multicenter study, the novel SMART-PVC/VT algorithm was developed based on an analysis of ECG features of patients undergoing catheter ablation for VAs between 2019 and 2024. The algorithm employs a structured, stepwise methodology incorporating QRS morphology patterns, transition zone assessment, and lead-specific voltage criteria (Figure 1). The algorithm was validated against intracardiac mapping data in a cohort of patients with idiopathic and structural heart disease-associated VAs.

Results:
A total of 309 patients (64±14 years old, 25% female) undergoing catheter ablation for 470 VAs were enrolled. The SMART-PVC/VT algorithm allowed for an accurate SOO localization (accuracy: 454/470, 97%) across multiple anatomical sites including the left and the right ventricle [accuracy 293/306 (96%); sensitivity 97%; specificity 99%; positive predictive value (PPV) 96%; negative predictive value (NPV) 100%], right and left ventricular outflow tracts [accuracy 128/131 (98%); sensitivity 98%; specificity 100%; PPV 99%; NPV 100%], as well as the parahisian region [accuracy 33/33 (100%); sensitivity 100%; specificity 100%; PPV 100%; NPV 100%].

Conclusion:
Our novel SMART-PVC/VT algorithm provides a systematic ECG-based method for precise and reliable SOO localization of PVCs. Its’ stepwise approach enhances accuracy, facilitating better procedural planning and improving ablation success rates.