Usefulness of non-contact mapping for catheter ablation of ventricular tachycardias originating at the right ventricular outflow tract

Background: Different QRS morphologies are often observed in idiopathic ventricular tachycardias or premature ventricular contractions originating from the right ventricular outflow tract (RVOT). However, the precise mechanism underlying multiple QRS morphologies has not been clarified adequately. The purpose of this study was to examine the mechanism underlying different QRS morphologies in RVOT arrhythmia. We also investigated the usefulness of non-contact mapping guided radiofrequency catheter ablation for RVOT arrhythmia. Methods: Endocardial mapping of RVOT was performed using a non-contact mapping system in 20 patients with RVOT arrhythmia. We analyzed the underlying mechanism that produces different QRS morphologies during catheter ablation of RVOT arrhythmia. Results: Forty-six QRS morphologies of RVOT arrhythmia were observed in 20 patients. Five patients showed monofocal QRS morphology, whereas the remaining 15 patients showed multiple QRS morphologies (from 2 to 4 morphologies each). Among these, all patients presented a shift in the origin of tachycardia. Additionally, different QRS morphologies were observed in 5 of these patients that were caused by a change in the local activation after radiofrequency energy delivery. Radiofrequency energy application to the site of origin of the RVOT arrhythmia using non-contact mapping navigation eliminated the RVOT arrhythmias in all patients. However, 1 patient presented a recurrence of RVOT arrhythmia (success rate, 95.0%). Conclusions: The multiple QRS morphologies of RVOT arrhythmia were caused by a shift in the origin of tachycardia or by a change in the local activation following the radiofrequency energy application. Non-contact mapping was useful to identify the appropriate target site of RVOT arrhythmia irrespective of the changes in QRS morphologies

Worldwide survey on implantation of and outcomes for conduction system pacing with His bundle and left bundle branch area pacing leads.

BACKGROUND Adoption and outcomes for conduction system pacing (CSP), which includes His bundle pacing (HBP) or left bundle branch area pacing (LBBAP), in real-world settings are incompletely understood. We sought to describe real-world adoption of CSP lead implantation and subsequent outcomes. METHODS We performed an online cross-sectional survey on the implantation and outcomes associated with CSP, between November 15, 2020, and February 15, 2021. We described survey responses and reported HBP and LBBAP outcomes for bradycardia pacing and cardiac resynchronization CRT indications, separately. RESULTS The analysis cohort included 140 institutions, located on 5 continents, who contributed data to the worldwide survey on CSP. Of these, 127 institutions (90.7%) reported experience implanting CSP leads. CSP and overall device implantation volumes were reported by 84 institutions. In 2019, the median proportion of device implants with CSP, HBP, and/or LBBAP leads attempted were 4.4% (interquartile range [IQR], 1.9-12.5%; range, 0.4-100%), 3.3% (IQR, 1.3-7.1%; range, 0.2-87.0%), and 2.5% (IQR, 0.5-24.0%; range, 0.1-55.6%), respectively. For bradycardia pacing indications, HBP leads, as compared to LBBAP leads, had higher reported implant threshold (median [IQR]: 1.5 V [1.3-2.0 V] vs 0.8 V [0.6-1.0 V], p = 0.0008) and lower ventricular sensing (median [IQR]: 4.0 mV [3.0-5.0 mV] vs. 10.0 mV [7.0-12.0 mV], p < 0.0001). CONCLUSION In conclusion, CSP lead implantation has been broadly adopted but has yet to become the default approach at most surveyed institutions. As the indications and data for CSP continue to evolve, strategies to educate and promote CSP lead implantation at institutions without CSP lead implantation experience would be necessary