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.

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.