The ultra-low-temperature cryoablation (ULTC) ablation system using −196°C N₂ cryogen has been reported to create lesions with freeze duration–dependent depth titratable to over 10 mm with minimum attenuation by scar. Cryocure-VT (NCT04893317) was a first-in-human clinical trial evaluating the safety and efficacy of a novel, purpose-built ULTC catheter in endocardial ablation of scar-dependent ventricular tachycardias (VTs). This prospective, multi-centre study enrolled patients referred for de novo or second ablations of recurrent monomorphic VT of both ischaemic and non-ischaemic aetiologies. Primary safety and efficacy endpoints of the study were freedom from device- or procedure-related major adverse events (MAEs) up to 30 days post-ablation, acute non-inducibility of clinical VTs at the end of the procedure, and freedom from sustained VT or implantable defibrillator intervention at 6 months. Ultra-low-temperature cryoablation was performed in 64 patients (age 67 ± 11 years, 78% ischaemic, ejection fraction = 35 ± 10%) at 9 centres. The primary acute effectiveness endpoint was achieved in 94% (51/54) of patients in whom post-ablation induction was attempted. There were no protocol-defined MAEs; four procedure-related serious adverse events resolved without clinical sequelae. At 6-month follow-up, 38 patients (60.3%) remained VT-free, and freedom from defibrillator shock was 81.0%, with no significant difference between ischaemic and non-ischaemic cohorts. In 47 patients with defibrillator for at least 6 months prior to the ablation, the VT burden was reduced from median of 4, inter-quartile range (IQR, 1–9) to 0, IQR (0–2). In this first-in-human multi-centre experience, endocardial ULTC ablation of monomorphic VT appears safe and effective in patients with both ischaemic-cardiomyopathy and non-ischaemic-cardiomyopathy. NCT04893317.

The right ventricular outflow tract (RVOT) is used as an alternative pacing site, but its superiority to the RV apex remains to be established. This lack of proof may in part be explained by heterogeneity within the RVOT-paced group, due to poor definitions of the RVOT. The aim of the present study is to characterize the RVOT in terms of fluoroscopic and electrocardiographic parameters. One hundred and forty-three patients who underwent pacemaker implantation with a ventricular lead in the RVOT were included. Lead position was determined by fluoroscopy. The RVOT was divided into three areas: anterior, septal, and free wall (FW). On a 12-lead electrocardiogram (ECG) during forced ventricular pacing, QRS duration, configuration, and amplitude was determined. Lead position was judged to be anterior in 52 (36%), septal in 43 (30%), and FW in 48 (34%) patients, respectively. QRS duration is not significantly different between groups. QRS axis differs significantly between pacing sites (septal 79 ± 31°, anterior 60 ± 46°, FW 47 ± 38°, P < 0.05). QRS vector in lead I and QRS morphology and vector in lead aVL differ significantly between pacing sites. Precordial transition is earlier (towards V1) in septal pacing. This study demonstrates heterogeneity of pacing site and depolarization pattern within a cohort of patients paced form the RVOT. However, due to considerable overlap, we could not define clear cut-off point or devise flow-charts to match ECG and pacing site.

During the diagnostic work-up of patients with idiopathic ventricular fibrillation (VF), next-generation sequencing panels can be considered to identify genotypes associated with arrhythmias. However, consensus for gene panel testing is still lacking, and variants of uncertain significance (VUS) are often identified. The aim of this study was to evaluate genetic testing and its results in idiopathic VF patients. We investigated 419 patients with available medical records from the Dutch Idiopathic VF Registry. Genetic testing was performed in 379 (91%) patients [median age at event 39 years (27–51), 60% male]. Single-gene testing was performed in 87 patients (23%) and was initiated more often in patients with idiopathic VF before 2010. Panel testing was performed in 292 patients (77%). The majority of causal (likely) pathogenic variants (LP/P, n = 56, 15%) entailed the DPP6 risk haplotype (n = 39, 70%). Moreover, 10 LP/P variants were found in cardiomyopathy genes (FLNC, MYL2, MYH7, PLN (two), TTN (four), RBM20), and 7 LP/P variants were identified in genes associated with cardiac arrhythmias (KCNQ1, SCN5A (2), RYR2 (four)). For eight patients (2%), identification of an LP/P variant resulted in a change of diagnosis. In 113 patients (30%), a VUS was identified. Broad panel testing resulted in a higher incidence of VUS in comparison to single-gene testing (38% vs. 3%, P < 0.001). Almost all patients from the registry underwent, albeit not broad, genetic testing. The genetic yield of causal LP/P variants in idiopathic VF patients is 5%, increasing to 15% when including DPP6. In specific cases, the LP/P variant is the underlying diagnosis. A gene panel specifically for idiopathic VF patients is proposed.

Background: There are few comparative studies on the everyday clinical outcomes of commercially available pulsed field ablation (PFA) systems for atrial fibrillation (AF). Objective: This study evaluates the acute efficacy and safety outcomes of the FARAPULSE™ (pentaspline catheter) and PulseSelect™ (circular catheter) system. Methods: International, multicenter, registry on patients with paroxysmal or persistent AF, undergoing a first ablation using either PFA system between January 29th, 2024 and September 1st, 2024. Primary endpoints were electrical isolation of ablation targets, procedural characteristics and freedom from major adverse events within 30 days postprocedure. Results: A total of 402 patients were enrolled at the six participating centers, of whom 56.5% were treated with the pentaspline ablation‐catheter. Acute procedural efficacy was 100% for both groups. Use of the pentaspline ablation‐catheter was associated with significantly shorter procedural times (36.0 min [IQR 31.0; 44.0] vs. 49.0 min [IQR 41.5;76.0]) compared to the circular ablation‐catheter ( p < 0.001). Major adverse events were scarce and not different between cohorts. Two patients (0.5%) experienced a stroke and one patient (0.2%) had a serious vascular access site complication. One patient had a transient ischemic attack (0.2%). Minor vascular access site complications were more common in the pentaspline catheter group (11.9% vs. 1.1%, p < 0.001). Conclusions: This study showed excellent acute efficacy and safety for both PFA‐systems. Our findings reveal shorter procedural times with the pentaspline catheter, less minor access site complications with the circular catheter, and several procedural differences between the ablation systems, often driven by operator choice.