Background: Radiofrequency(RF) ablation of premature ventricular complexes(PVCs) is a well-established treatment for patients high PVCs burden, even when arising from epicardial/intramural localization. Consistent data about safety of using high power RF is lacking in literature in these regions. Aim: The aim of this study is to investigate safety of different RF power settings, efficacy and outcome of non-endocardial PVCs ablation. Methods: Consecutive patients who underwent PVC ablation were included (2017-2023). We defined “Non-Endocardial Radiofrequency Ablation”(NERA) a procedure in which at least one ablation site has been identified into the cardiac venous system, aortic cusps, inter-leaflet region or pulmonary cusps. Results: Total number of NERA sites was 64 in 53 procedures. In 63% of the procedures, high power (≥40W) and in 60% long duration (≥60 seconds) RF was delivered in at least one site (mean power:37±9W(15-50), mean duration of single RF 88±65 seconds (30-304)). In 21% of the procedures, a combination of both high power and long duration RF applications was performed. Procedural success was achieved in 47 procedures(84%). Only one severe complication (pericardial bleeding) was observed. In 22(39%) procedures, multisite ablation was performed which was associated with procedural failure (OR 7,47;p=0,01). During follow-up, mean and median PVC burden reduction were 69±41% and 96% respectively. Multisite ablation and coronary venous system RF were predictors of recurrence (HR 3.6;p=0.026 and HR 3.85;p=0.014). Conclusion: Ablation from non-endocardial sites is a safe and effective procedure, even using high power and/or long duration RF with clear benefit in terms of PVC burden reduction.

Is Multipoint Pacing Superior to Optimized Single-Point Pacing?Rodolfo San Antonio1, MD; Jose María Tolosana2, MD, PhD; Lluís Mont2, MD, PhD.1Heart Institute, Teknon Medical Center, Barcelona, Spain; University of Barcelona, Spain2Institut Clínic Cardio-Vascular, Hospital Clínic, University of Barcelona, Spain; Institut d’Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), Barcelona, Spain; Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain.Word count: 434

Background: Temporary transvenous pacing in critically ill patients requiring prolonged cardiac pacing is associated with a high risk of complications. We sought to evaluate the safety and efficacy of self-contained intracardiac leadless pacemaker (LPM) implantation in this population. Methods and Results: Consecutive patients implanted with a Micra LPM during the hospitalization in an intensive care unit were retrospectively included. Inclusion criteria were: ≥1 supracaval central venous, or a ventilation tube, or intravenous antibiotic therapy for ongoing sepsis or bacteremia. Patients with a history of previous implantation of a pacemaker were excluded. Out of 1,016 patients implanted with an LPM, 99 met the inclusion criteria. Mean age was 75 years and Charlson comorbidity index 7. LPM implantation was successfully performed in 98% of cases, with a peri-operative complication rate of 5%, mainly cardiac injuries. In-hospital mortality rate was 6%. No late (>30 days) device-related complication occurred, especially no infection. Conclusions: LPM appears as an acceptable alternative to conventional temporary transvenous pacing in selected critically ill patients requiring prolonged cardiac pacing, especially regarding the risk of infection.

Background: Multipoint pacing (MPP) in cardiac resynchronization therapy (CRT) activates the left ventricle from two locations, thereby shortening the QRS duration and enabling better resynchronization; however, compared with conventional CRT, MPP reduces battery longevity. On the other hand, electrocardiogram-based optimization using the fusion-optimized intervals (FOI) method achieves more significant reverse remodeling than nominal CRT programming. Our study aimed to determine whether MPP could attain better resynchronization than single-point pacing (SPP) optimized by FOI. Methods: This prospective study included 32 consecutive patients who successfully received CRT devices with MPP capabilities. After implantation, the QRS duration was measured during intrinsic rhythm and with three pacing configurations: MPP, SPP-FOI, and MPP-FOI. In 14 patients, biventricular activation times (by electrocardiographic imaging, ECGI) were obtained during intrinsic rhythm and for each pacing configuration to validate the findings. Device battery longevity was estimated at the 45-day follow-up. Results: The SPP-FOI method achieved greater QRS shortening than MPP (-56±16 vs. -42±17 ms, P<0.001). Adding MPP to the best FOI programming did not result in further shortening (MPP-FOI: - 58±14 ms, P=0.69). Furthermore, the biventricular activation time according to ECGI was also shorter with SPP-FOI than with MPP. The estimated battery longevity was longer with SPP than with MPP (8.1±2.3 vs. 6.3±2.0 years, P=0.03). Conclusions: SPP optimized by FOI resulted in better resynchronization and longer battery duration than MPP.

LEARNING OBJECTIVES-       Sustained re-entrant tachyarrhythmias treatment has become pivotal in the grown-up congenital heart patients clinical management. -       Cardiac LGE-MRI tissue characterization integrated with high definition electroanatomic map could allow fast recognition and effective treatment of substrate of tachyarrhythmias.-       Cardiac LGE-MRI areas were suggestive of post-surgical changes both in atrium and ventricle. -       High-density electro-anatomical map localized areas of slow conduction identifying conducting isthmuses of re-entrant arrhythmias.