Wataru Shimizu

The Japanese Catheter Ablation (J‐AB) registry, started in August 2017, is a voluntary, nationwide, multicenter, prospective, observational registry performed by the Japanese Heart Rhythm Society (JHRS) in collaboration with the National Cerebral and Cardiovascular Center. From January 2022, the data registration system was changed from Research Electronic Data Capture (REDCap) system to Fountayn system. The purpose of this registry is to collect the details of target arrhythmias, the ablation procedures, including the types of target arrhythmias, outcomes, and acute complications in the real‐world settings. During the year 2024, we have collected a total of 112 151 procedures (mean age of 67.5 years and 65.2% male) from 589 participant hospitals. Detailed data were shown in Figures and Tables.

SCN5A-E1784K (c.5350G>A) is the most common variant associated with the long QT (LQTS) and Brugada syndromes (BrS). It can manifest variably as LQTS, BrS and/or conduction disorders. This presents a challenge for risk stratification. We aimed to describe clinical and ECG characteristics and identify risk markers that associate with arrhythmic events. We undertook a retrospective observational multicentre study of a large cohort of 231 subjects with SCN5A-E1784K from Europe, USA and Japan. Comprehensive demographic and clinical data, including initial presentation ECG and follow-up, were collected. ‘Lethal events’ were defined as sudden death, non-fatal cardiac arrest, and documented sustained VT or VF. ‘Cardiac events’ were defined as arrhythmic syncope plus any lethal events. Clinical characteristics and ECG parameters corrected for age were investigated for association with lethal and/or cardiac events. Fourteen (6%) subjects experienced a lethal event and 45 (19%) a cardiac event. PR interval and QRS duration were associated with lethal and cardiac events. In multivariable models, both PR interval and QRS duration were associated with lethal events but only QRS duration was associated with cardiac events. Only age-corrected QRS (rQRS) was associated with lethal and cardiac event-free survival from birth after correction for multiple testing. Ventricular myocardial conduction appears likely to play a role in the risk of arrhythmic events in patients with SCN5A-E1784K. This provides an important opportunity for the personalisation of management and has the potential to guide preventative therapies.

J‐wave syndromes (JWS)—comprising Brugada syndrome (BrS) and early repolarization syndrome (ERS)—are important causes of malignant ventricular arrhythmias and sudden cardiac death in patients whose hearts appear structurally normal. Since the 2016 consensus, advances in genetics, pathophysiology, and therapy have redefined both understanding and management. BrS, once viewed as a purely electrical disorder, is now recognized along a microstructural–electrical continuum, with sodium‐channel dysfunction and subtle epicardial fibrosis of the right ventricular outflow tract as key contributors. Likewise, ERS—historically considered benign—carries significant risk when inferolateral J‐waves coexist with arrhythmic events. Genetically, SCN5A remains the sole gene with definitive disease association, while polygenic susceptibility materially modulates risk, underscoring complex inheritance. Risk stratification remains challenging: patients with prior cardiac arrest or arrhythmic syncope are highest risk, whereas asymptomatic individuals warrant multiparametric assessment integrating clinical features, ECG markers, electrophysiologic studies, and genetics. For decades, treatment centered on implantable cardioverter‐defibrillators and quinidine, both limited by availability, tolerance, and device complications. More recently, epicardial substrate ablation has emerged as a transformative therapy, with large registries and randomized trials demonstrating durable suppression of ventricular fibrillation and acceptable safety. This APHRS‐organized international consensus updates and extends the 2016 Expert Consensus and the 2022 ESC Guidelines, providing contemporary diagnostic frameworks, pragmatic risk‐stratification tools, and treatment algorithms for BrS and ERS. It emphasizes JWS as a microstructural–electrical disease spectrum and elevates substrate ablation as a major therapeutic advance, while outlining priorities for genetics, risk‐stratification and treatment algorithms.

Background and Aims: Patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) are at risk for potentially life-threatening arrhythmic events (AEs) even while treated with β-blockers. The aim was to develop a model for individualized prediction of AEs in patients with RYR2-mediated CPVT on β-blocker monotherapy. Methods: The derivation and independent validation cohorts included 743 and 129 patients, respectively. AEs were defined as arrhythmic syncope, appropriate implantable cardioverter–defibrillator shock, sudden cardiac arrest (SCA), and sudden cardiac death. Near-fatal or fatal AEs (nf/fAEs) included all AEs except for arrhythmic syncope. Prediction models using Cox regression were developed and internally and externally validated. Results: A total of 102 (13.7%) patients in the derivation cohort and 24 (18.6%) patients in the validation cohort experienced ≥1 AE over a median follow-up of 5.1 [interquartile range (IQR), 7.7] and 2.4 (IQR, 4.4) years, respectively. Predictors of AE were arrhythmic syncope or SCA prior to diagnosis and age at β-blocker initiation. In the derivation and validation cohorts, the optimism-corrected C-indices of the models for AE were 0.67 [95% confidence interval (CI) 0.62–0.72] and 0.59 (95% CI 0.48–0.71), respectively. For nf/fAEs, ventricular arrhythmia severity before β-blocker initiation was a fourth independent predictor, and C-indices of the models in the derivation and validation cohorts were 0.74 (95% CI 0.68–0.80) and 0.60 (95% CI 0.47–0.72), respectively. In the derivation cohort, calibration slopes were 1.00 (95% CI 0.59–1.41) for AE and 1.00 (95% CI 0.69–1.32) for nf/fAE. Conclusions: These externally validated risk prediction models using clinical parameters accurately distinguished CPVT patients on β-blocker monotherapy at low and high risk for future AEs while treated with β-blockers. These models provide guidance for implementation of clinical management therapies to prevent AEs in patients with CPVT.

The Japanese Heart Rhythm Society established a nationwide, mandatory, multi‐center, prospective, observational registry of transvenous lead extraction (TLE) named the Japanese lead extraction registry (J‐LEX) in 2018. As of the end of 2024, a cumulative total of approximately 5400 cases has been registered across 140 participating centers since 2018. The registry includes all consecutive transvenous extractions, excluding surgical‐only cases. The indication of TLE was an infection in 54.5%, and the guideline classification was class I in 59.8% and class IIa in 21.8%. As for non‐infectious indications, TLE is performed for abandoned leads in case of lead failure or device upgrade, and for lead‐related trouble such as pain, vessel stenosis or occlusion, too many leads, tricuspid valve regurgitation, and difficulty with radiation therapy. In 2024, the TLE procedure was attempted on patients with a median age of 71.3 years, female in 32.7%, in the hybrid operating room in 73.3%, and in a standard OR with a C‐arm fluoroscope in 11.5%. The average implantation duration of the target leads was 8.5 years. Complete removal was achieved in 96.7% of the target leads, and clinical success in 97.3% of the patients. Perioperative complications were observed in 4.8% of the patients. Three patients died during a TLE operation, and 11 patients died in‐hospital (cardiac death in three patients and non‐cardiac death in eight patients).

Background: Heart rate score (HrSc) ≥ 70% reflects chronotropic incompetence and predicts prognosis in patients with cardiac implantable electronic devices (CIEDs) and left ventricular (LV) systolic dysfunction. However, its prognostic value in Japanese patients remains underexplored, and longitudinal changes in HrSc and their contributing factors are poorly characterized. Methods: This post hoc analysis of the Heart Failure Indication and Sudden Cardiac Death Prevention Trial in Japan (HINODE) included 172 patients with CIEDs and LV ejection fraction ≤ 50%. HrSc, defined as the percentage of all atrial‐paced and sensed beats in a single tallest 10 beat/min device histogram bin, was assessed using remote monitoring. Results: At baseline, the median HrSc was 53% (interquartile range, 41%–83%), with 68 (39.5%) patients having HrSc ≥ 70%. During the 2‐year follow‐up, the incidence of all‐cause death or heart failure (HF) events was similar between patients with HrSc ≥ 70% and < 70% (31.1% vs. 29.4%, log‐rank p = 0.862). However, among 142 patients whose follow‐up data were available, HrSc increased from < 70% to ≥ 70% in 13 patients (13%) and decreased from ≥ 70% to < 70% in 19 (9.1%). An increase in HrSc was associated with lower LV ejection fraction, antiarrhythmic drug initiation, increased lower rate limit, and HF events. Conclusion: In the HINODE study, baseline HrSc ≥ 70% was not predictive of 2‐year cardiovascular outcomes. However, HrSc changed in approximately one‐quarter of patients and was associated with clinical and device‐related factors, as well as HF events. HrSc is not a static measure but a dynamic marker that reflects evolving patient conditions and CIED programming.