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Background: Atrial tachyarrhythmias (ATAs) are the primary cause of inappropriate implantable cardioverter-defibrillator (ICD) therapy in patients with idiopathic ventricular fibrillation (IVF) and are associated with decreased quality of life and increased mortality. Nonetheless, the incidence of ATAs in IVF cases has not been clarified. Objective: The study sought to determine the incidence and clinical significance of ATAs in patients with IVF compared with those with Brugada syndrome (BrS). Methods: Patients diagnosed with IVF or BrS and receiving ICDs in 6 hospitals were enrolled between February 1997 and July 2020 to compute data regarding the incidence of ATAs, appropriate/inappropriate ICD therapy frequency, and independent predictors of ATAs. Results: Overall, 137 patients (51 in the IVF group and 86 in the BrS group) were enrolled. ATAs were detected in 22 (43.1%) patients in the IVF group and 17 (19.8%) in the BrS group (P = .006). Inappropriate ICD therapies due to ATAs were more frequently observed in the IVF group than in the BrS group (12 [23.5%] vs 7 [8.1%]; P = .020). Conversely, there was no significant difference in appropriate ICD therapies between the IVF and BrS groups (14 [27.5%] vs 23 [27.1%]; P = 1.000). Cox regression analysis revealed no predictive factors for the development of ATAs in the IVF group. Conclusion: ATA events were observed more frequently in patients with IVF than in those with BrS, and ATAs led to inappropriate ICD therapy in patients with IVF. Clinicians need to consider the recurrence of not only ventricular arrhythmias, but also the development of atrial arrhythmias for better management of IVF cases.

Background: Syncope is a significant prognostic factor in patients with Brugada syndrome (BrS). However, the risk of ventricular arrhythmia in patients with nonarrhythmic loss of consciousness (LOC) is similar to that in asymptomatic patients. LOC events after implantable cardioverter-defibrillator (ICD) implantation may provide insights into underlying causes of the initial LOC episode. Objective: The purpose of this study was to examine LOC characteristics following ICD implantation. Methods: We retrospectively analyzed 112 patients with BrS (mean age 47 years; 111 men) who were treated with an ICD. The patients were classified into 3 groups based on symptoms at implantation: asymptomatic (35 patients); LOC (46 patients); and ventricular tachyarrhythmia (VTA) (31 patients). We evaluated the incidence and cause of LOC during long-term follow-up after ICD implantation. Results: During mean follow-up of 12.2 years, 41 patients (37%) experienced LOC after ICD implantation. Arrhythmic LOC occurred in 5 asymptomatic patients, 14 LOC patients, and 16 patients with VTA. Nonarrhythmic LOC, similar to the initial episode, occurred after ICD implantation in 6 patients with prior LOC (2 with neurally mediated syncope and 4 with epilepsy). Most epileptic patients experienced LOC during rest or sleeping, and did not show an abnormal encephalogram during initial evaluation of the LOC episodes. Conclusion: After ICD implantation, 13% of patients had nonarrhythmic LOC similar to the initial episode. Accurate classification of LOC based on a detailed medical history is important for risk stratification, although distinguishing arrhythmic LOC from epilepsy-related LOC episodes can be challenging depending on the circumstances and characteristics of the LOC event.

Aims: Sudden cardiac death (SCD) is a major cause of mortality in adults with congenital heart disease (ACHD). The role of implantable cardioverter-defibrillator (ICDs) in preventing SCD has been established, however, robust, clinical evidence-based guidelines are lacking in ACHD. The aim of this study was to evaluate the ICD guidelines in ACHD patients. Methods and Results: A total of 131 ACHD patients (male: n = 96 (73.3%), mean age: 42.8 ± 14.7 years, mean follow-up: 40.9 ± 28.3 months) undergoing ICDs implantation between 2010 and 2017 were reviewed. Sixty-nine patients (52.6%) received ICDs for a primary prevention indication. 122 (93.3%) patients had congenital heart disease of moderate to severe complexity. CRT-D (implantable cardiac resynchronization defibrillator) was implanted in 55 (42.0%) patients. During follow-up, 23 patients (17.6%) received appropriate ICD therapy. According to the current guideline (PACES/HRS 2014), 84 (64.1%), 8 (6.1%), and 39 (29.8%) could be classified as Class Ⅰ, Class Ⅱa, and Class Ⅱb indication, respectively. Compared to patients with Class Ⅱa and IIb indication, those with Class Ⅰ indication received more appropriate therapy (P = 0.030). Multivariate analysis showed that age (per 10-years decrease; P = 0.015, HR 1.254 CI; 1.045–1.505) and creatinine (per 100-μmol/L increase; P = 0.019, HR 1.555 CI; 1.076–2.247) were associated with appropriate therapy. Conclusion: Implantation of ICDs for preventing SCD based on current guidelines is reasonable. For patients with a borderline indication, younger age and renal dysfunction may aid in the selection of ICDs candidates.

Background: Implantable cardioverter defibrillators (ICDs) are effective in preventing arrhythmic sudden cardiac death in patients with tetralogy of Fallot (TOF). Although ICD therapies for malignant ventricular arrhythmias can be life-saving, shocks could have deleterious consequences. Substrate-based ablation therapy has become the standard of care to prevent recurrent ICD shocks in patients with ischemic cardiomyopathy. However, the efficacy and safety of this invasive therapy in the prevention of recurrent ICD shocks in patients with TOF has not been well evaluated. Methods: Records of a total of 47 consecutive TOF patients (mean age: 43.1 ± 13.2 years, male sex: n = 34 [72.3%]) who underwent ICD implantation for secondary prevention between 2000 and 2018 were reviewed. Results: Twenty (42.6%) patients underwent invasive therapy (radiofrequency catheter ablation, n = 8; surgical ablation with pulmonary valve replacement, n = 12) before ICD implantation. Twenty-seven patients (57.4%) were managed noninvasively. During follow-up (median 80.5 [interquartile range, 28.5-131.0] months), 2 (10.0%) patients in the invasive group and 10 (37.0%) patients in the noninvasive group received appropriate ICD shocks (P = 0.036). Logistic regression analysis showed that invasive therapy was associated with a decreased risk of ICD shocks by 81.1% (odds ratio, 0.189; 95% confidence interval, 0.036-0.990; P = 0.049). Furthermore, invasive therapy was associated with decreased risk of the composite outcomes of ICD shock, death, cardiac transplantation, and hospital admission (odds ratio, 0.090; 95% confidence interval, 0.025-0.365; P = 0.013) compared with noninvasive therapy. Conclusions: Invasive substrate modification therapy was associated with a lower likelihood of ICD shocks and improvement of long-term outcomes in TOF patients. Résumé: Contexte: Les défibrillateurs cardioverteurs implantables (DCI) sont efficaces pour prévenir la mort cardiaque subite provoquée par une arythmie chez les patients présentant une tétralogie de Fallot (TF). Bien que le traitement des arythmies ventriculaires malignes par DCI puisse sauver des vies, les chocs administrés peuvent avoir des conséquences délétères. L’ablation du substrat est devenue le traitement de référence pour prévenir l’administration à répétition de chocs par DCI chez les patients atteints d’une cardiomyopathie ischémique. L’efficacité et l’innocuité de ce traitement invasif pour prévenir l’administration de chocs répétés chez les patients présentant une TF n’ont toutefois pas été bien évaluées. Méthodologie: Nous avons examiné les cas consécutifs de 47 patients présentant une TF (âge moyen : 43,1 ± 13,2 ans; hommes : n = 34 [72,3 %]) ayant reçu un DCI en prévention secondaire entre 2000 et 2018. Résultats: Au total, 20 (42,6 %) patients ont subi un traitement invasif (ablation par cathéter par radiofréquence, n = 8; ablation chirurgicale et remplacement de la valve pulmonaire, n = 12) avant l’implantation d’un DCI. Vingt-sept patients (57,4 %) ont été pris en charge de façon non invasive. Au cours de la période de suivi (durée médiane de 80,5 [intervalle interquartile : 28,5 à 131,0] mois), 2 (10,0 %) patients du groupe ayant subi une intervention invasive et 10 (37,0 %) patients du groupe ayant subi une intervention non invasive ont reçu un choc approprié par DCI (p = 0,036). Les résultats de l’analyse par régression logistique montrent que le traitement invasif est associé à une réduction du risque de choc par DCI de 81,1 % (rapport des cotes : 0,189; intervalle de confiance à 95 % : de 0,036 à 0,990; p = 0,049). En outre, le traitement invasif est associé à une réduction du risque de survenue d’un des événements du paramètre d’évaluation composé, soit un choc administré par DCI, le décès, une transplantation cardiaque ou une hospitalisation (rapport des cotes : 0,090; intervalle de confiance à 95 % : de 0,025 à 0,365; p = 0,013) par rapport au traitement non invasif. Conclusions: La modification invasive du substrat a été associée à une probabilité plus faible de choc administré par DCI et à une amélioration des résultats à long terme chez les patients présentant une TF.