Reappraisal of the clinical and anatomic characteristics of idiopathic outflow tract ventricular arrhythmias with an R wave pattern break in precordial lead: A multi-center study.

Background: Idiopathic outflow tract ventricular arrhythmia (OT-VA) with a pattern break (PB) in the precordial leads is challenging to treat and is associated with low success rates. Objective: Describe the anatomic characteristics and outcomes of patients with PB idiopathic OT-VA underwent catheter ablation. Methods: We retrospectively reviewed the electronic medical records of idiopathic OT-VA patients underwent catheter ablation at Taipei Veterans General Hospital, Taiwan, and Makiminato Central Hospital, Japan. Patients with a documented left bundle branch block (LBBB) pattern and inferior axis VA QRS morphology with PB were included. Clinical data, VA morphology, electrophysiological parameters, and anatomic characteristics were analyzed. Results: A total of 66 patients (6.7 %) had a PB in V2 (N = 60) or V3 (N = 6) were identified. The acute and long-term success rates (after a median follow-up of 37 months) were 92.4 % and 78.8 %, respectively, higher than previously reported. The successful ablation sites were mainly the right ventricular outflow tract (RVOT, 81.8 % [54/66]). The earliest activation site in the LVOT was mainly the left coronary cusp (LCC)/right coronary cusp (RCC) commissure (95.7 %, 22/23). A long anatomic distance from the LCC/RCC commissure to the RVOT and diabetes mellitus (DM) independently predicted acute procedural failure or recurrence. Conclusion: OT-VA with PB in the Asian population may not have worse clinical outcomes than previously reported in Western countries. The most common site of acute success for ablation was the RVOT. A long anatomic distance from the LCC/RCC commissure to the RVOT and DM diagnosis was associated with an unsatisfied ablation outcome.