A hybrid score to predict the origin of outflow tract ventricular arrhythmias in patients with intraventricular conduction disorders or paced rhythm

Abstract Background The identification of outflow tract ventricular arrythmia (OTVA) site of origin (SOO) is of crucial importance for the ablation planning. Previous published algorithms have been validated only in patients with narrow QRS during sinus rhythm; furthermore, some scores have been developed by comparing characteristics of the OTVA with those of the sinus rhythm QRS, reducing their performance when applied to patients with intraventricular conduction disorder or paced rhythm. Purpose The present study sought to evaluate the performance of a previously published clinic and electrocardiographic hybrid score (HS) for the prediction of OTVA-SOO in a cohort of patients with wide QRS during sinus or paced rhythm, making a comparison with other published algorithms (NCT06602635). Methods In this multicenter international study, we retrospectively included patients with intraventricular conduction disorder or paced rhythm who underwent OTVA ablation. The HS consists of an algebraic sum according to clinical characteristics (age over 50 years, male sex, and arterial hypertension) and to ECG precordial transition of the OTVA (Figure 1). Results Seventy-two patients (age 62±15 years; 80.8% males) were included in the study. In the studied population, the most prevalent OTVA-SOO was left ventricle outflow tract (75%) compared to right ventricle outflow tract (25%). 50% of patients were hypertensive, 62% of patients have a diagnosis of cardiomyopathy, with the most common diagnosis being non-ischemic cardiomyopathy. The mean baseline QRS duration was 129±23 ms. The most frequent electrical conduction disorder was advanced left anterior fascicular block (29%), 24% of patients presented right bundle branch block, 12% left bundle branch block, 4% left posterior fascicular block, 24% paced rhythm; the other patients presented non-specific intraventricular conduction disorder. Regarding correct OTVA-SOO prediction in the study population, HS achieved an accuracy value of 90% (92% sensitivity, 86% specificity, AUC: 0.97), reporting prediction performance superior to that of previously published ECG scores (accuracy ranging from 63% to 85% and AUC ranging from 0.56 to 0.92) (Figure 2). Conclusion The HS has proved to accurately anticipate the OTVA-SOO in a consecutive population of patients presenting wide baseline QRS, demonstrating better performances than the scores published so far. Most patients with wide baseline QRS presented left-sided OTVA-SOO.