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Abstract Background Despite the positive impact of implantable cardioverter defibrillators (ICDs) and wearable cardioverter defibrillators (WCDs) on prognosis, their implantation is often withheld especially in Japanese heart failure patients with reduced left ventricular ejection fraction (HFrEF) who have not experienced ventricular tachycardia (VT) or ventricular fibrillation (VF) for uncertain reasons. Recent advancements in heart failure (HF) medications have significantly improved the prognosis for HFrEF. Given this context, a critical reassessment of the treatment and prognosis of ICDs and WCDs is essential, as it has the potential to reshape awareness and treatment strategies for these patients. Methods We are initiating a prospective multicenter observational study for HFrEF patients eligible for ICD in primary and secondary prevention, and WCD, regardless of device use, including all consenting patients. Study subjects are to be enrolled from 31 participant hospitals located throughout Japan from April 1, 2023, to December 31, 2024, and each will be followed up for 1 year or more. The planned sample size is 651 cases. The primary endpoint is the rate of cardiac implantable electronic device implementation. Other endpoints include the incidence of VT/VF and sudden death, all‐cause mortality, and HF hospitalization, other events. We will collect clinical background information plus each patient's symptoms, Clinical Frailty Scale score, laboratory test results, echocardiographic and electrocardiographic parameters, and serial changes will also be secondary endpoints. Results Not applicable. Conclusion This study offers invaluable insights into understanding the role of ICD/WCD in Japanese HF patients in the new era of HF medication.

Abstract Extremely low alanine aminotransferase (ALT) may reflect aging, frailty, sarcopenia, and malnutrition in several cardiovascular diseases, but the association between low ALT and patient characteristics, cardiovascular and all-cause mortality is not well investigated in the population with atrial fibrillation. We conducted a post hoc analysis of a prospective, observational multicenter study. Patients with nonvalvular AF in the SAKURA AF Registry (n = 3156) were classified into 3 tertiles according to baseline ALT: first (ALT ≤ 15 U/L, n = 1098), second (15

Introduction Data are lacking on the extent to which patients with non-valvular atrial fibrillation (AF) who are aged ≥80 years benefit from ablation treatment. The question pertains especially to patients’ postablation quality of life (QoL) and long-term clinical outcomes.Methods and analysis We are initiating a prospective, registry-based, multicentre observational study that will include patients aged ≥80 years with non-valvular AF who choose to undergo treatment by catheter ablation and, for comparison, such patients who do not choose to undergo ablation (either according to their physician’s advice or their own preference). Study subjects are to be enrolled from 52 participant hospitals and three clinics located throughout Japan from 1 June 2022 to 31 December 2023, and each will be followed up for 1 year. The planned sample size is 660, comprising 220 ablation group patients and 440 non-ablation group patients. The primary endpoint will be the composite incidence of stroke/transient ischaemic attack (TIA) or systemic embolism (SE), another cardiovascular event, major bleeding and/or death from any cause. Other clinical events such as postablation AF recurrence, a fall or bone fracture will be recorded. We will collect standard clinical background information plus each patient’s Clinical Frailty Scale score, AF-related symptoms, QoL (Five-Level Version of EQ-5D) scores, Mini-Mental State Examination (optional) score and laboratory test results, including measures of nutritional status, on entry into the study and 1 year later, and serial changes in symptoms and QoL will also be secondary endpoints. Propensity score matching will be performed to account for covariates that could affect study results.Ethics and dissemination The study conforms to the Declaration of Helsinki and the Ethical Guidelines for Clinical Studies issued by the Ministry of Health, Labour and Welfare, Japan. Results of the study will be published in one or more peer-reviewed journals.Trial registration number UMIN000047023.

Abstract Background Limited data exist on indicators of durable pulmonary vein isolation (PVI) undergoing cryoballoon ablation (CBA) for atrial fibrillation (AF). We investigated whether balloon temperature and time to PVI can be used to predict early PV reconduction (EPVR), including residual PV conduction and adenosine triphosphate‐induced dormant conduction and the relation between touch‐up ablation of EPVR sites and mid‐term recurrence of AF. Methods We obtained procedural and outcome data from the records of 130 consecutive patients who underwent CBA and followed up for 13.4 months. Results EPVR was identified in 86 (17%) PVs of 61 (47%) patients. Balloon temperatures during 30 seconds (−27 ± 5.7°C vs −31 ± 5.5°C), 60 seconds (−36 ± 5.6°C vs −41 ± 5.4°C), and at the nadir point (−41 ± 7.4°C vs −49 ± 7.0°C) were significantly higher, and the time to PVI was longer (90 ± 50 seconds vs 52 ± 29 seconds) in PVs with EPVR than in those without (P

Background: The relationship between cardiac contrast-enhanced magnetic resonance imaging (CE-MRI)-derived scar characteristics and substrate for ventricular tachycardia (VT) in patients with structural heart disease (SHD) has not been fully investigated. Methods: This study included 51 patients (mean age, 63.3±15.1 years) who underwent CE-MRI with SHD and VT induction testing before ablation. Late gadolinium-enhanced (LGE) regions on MRI slices were quantified by thresholding techniques. Signal intensities (SIs) 2–6 SDs above the mean SI of the remote left ventricular (LV) myocardium were considered as scar border zones, and SI>6 SDs, as scar zone, and the scar characteristics related to VT inducibility and successful ablation via endocardial approaches were evaluated. Results: The proportion of the total CE-MRI-derived scar border zone in the inducible VT group was significantly greater than that in the non-inducible VT group (26.3±9.9% vs. 19.2±7.8%, respectively, P=0.0323). The LV endocardial scar zone to total LV myocardial scar zone ratio in patients whose ablation was successful was significantly greater than that in those whose ablation was unsuccessful (0.61±0.11 vs. 0.48±0.12, respectively, P=0.0042). Most successful ablation sites were located adjacent to CE-MRI-derived scar border zones. Conclusions: By CE-MRI, we were able to characterize not only the scar, but also its location and heterogeneity, and those features seemed to be related to VT inducibility and successful ablation from an endocardial site.

Background: The mechanisms underlying self-perpetuation of persistent atrial fibrillation (AF) are not well understood. To gain insight into these mechanisms, we conducted a study comparing left atrial (LA) electroanatomic maps obtained during sinus rhythm between patients with paroxysmal AF (PAF) and patients with persistent AF (PerAF). Methods: The study included 23 men with PAF (age, 56.3±12.1 years) and 13 men with PerAF (age, 54.3±13.4 years). LA voltage mapping was performed during sinus rhythm. The clinical and electroanatomic characteristics of the two groups were evaluated and analyzed statistically. Results: The bipolar voltages at the LA septum, roof, and posterior wall, right superior pulmonary vein (PV) and its antrum, right superior PV carina, and right inferior PV antrum were significantly lower in patients with PerAF than in those with PAF. The bipolar voltages in other parts of the LA did not differ statistically between the two groups. Conclusion: PAF and PerAF seem to be characterized by differences in the regional voltage in the LA and PVs. The LA structural remodeling of PerAF may initiate from the right PVs and their antra and LA septum, roof, and posterior wall.

Background: Ablation targeting complex fractionated atrial electrograms (CFAEs) or high dominant frequency (DF) sites is generally effective for persistent atrial fibrillation (AF). CFAEs and/or high DF sites may exist in low-voltage regions, which theoretically represent abnormal substrates. However, whether CFAEs or high DF sites reflect low voltage substrates during sinus rhythm (SR) is unknown. Methods: Sixteen patients with AF (8 with paroxysmal AF; 8, persistent AF) underwent high-density mapping of the left atrium (LA) with a 3-dimensional electroanatomic mapping system before ablation. The LA was divided into 7 segments and the mean bipolar voltage recorded during AF and SR, CFAEs (cycle lengths of 50–120 ms), and DF sites were assessed in each segment with either a duo-decapolar ring catheter (n=10) or a 64-pole basket catheter (n=6). Low-voltage areas were defined as those of 8 Hz) did not correlate with % low-voltage sites during SR; however, CFAEs sites were located in high-voltage regions during AF and high DF sites were located in low voltage regions during AF. Conclusions: CFAEs and high DF areas during AF do not reflect damaged atrial myocardium as shown by the SR voltage. However, CFAEs and high DF sites may demonstrate different electrophysiologic properties because of different voltage amplitude during AF.

Background: Although alteration of the amplitude and morphology of bipolar electrograms is used widely as a guide of the ablation effect, there is little information concerning unipolar electrograms. The amplitude and morphology of filtered bipolar (BP) and filtered unipolar (UP) electrograms were compared during pulmonary vein isolation in patients with atrial fibrillation. Methods: BP (30–250 Hz) and UP (30–100 Hz) signals from the ablation catheter were recorded before and after each ablation point at the pulmonary vein antrum in 6 patients with atrial fibrillation. Results: In the electrogram group with low-voltage amplitude in BP electrograms before ablation (

Background: Complex fractionated atrial electrograms (CFAEs) and high dominant frequency (DF) are targets for atrial fibrillation (AF) ablation. Although adenosine triphosphate (ATP) is known to promote AF by shortening the atrial refractory period, its role in the pathogenesis of CFAEs and DF during AF is not fully understood. Methods: We recorded electrical activity from a 64-electrode basket catheter placed in the left atrium (LA) of patients with paroxysmal AF (PAF, n=18) or persistent AF (PerAF, n=19) before ablation. Atrial electrogram fractionation intervals (FIs) and DFs were measured from bipolar electrograms of each adjacent electrode pair. Offline mean atrial FIs and DFs were obtained before bolus injection of 30 mg ATP. Peak effect was defined as an R–R interval >3 s. Results: With ATP, the mean FI decreased (from 110.4±29.1 ms to 90.5±24.7 ms, P

Background: Because obesity is an important risk factor for atrial fibrillation (AF), we conducted an animal study to examine the effect of a high-fat diet (HFD) on atrial properties and AF inducibility. Methods: Ten 8-week-old pigs (weight, 18–23 kg) were divided into two groups. For 18 weeks, five pigs were fed a HFD (HFD group) and five were fed a normal diet (control group). Maps of atrial activation and voltages during sinus rhythm were created for all pigs using the EnSite NavX system. Effective refractory period (ERP) and AF inducibility were also determined. When AF was induced, complex fractionated atrial electrogram (CFAE) mapping was performed. At 18 weeks, hearts were removed for comparing the results of histological analysis between the two groups. Body weight, lipid levels, hemodynamics, cardiac structures, and electrophysiological properties were also compared. Results: Total cholesterol levels were significantly higher (347 [191–434] vs. 81 [67–88] mg/dL, P=0.0088), and left atrium pressure was higher (34.5 [25.6–39.5] vs. 24.5 [21.3–27.8] mmHg, P=0.0833) in the HFD group than in the control group, although body weight only increased marginally (89 [78–101] vs. 70 [66–91] kg, P=0.3472). ERPs of the pulmonary vein (PV) were shorter (P

Background: The presence of complex fractionated atrial electrograms (CFAEs) and high dominant frequencies (DFs) during atrial fibrillation (AF) have been demonstrated to be related to AF maintenance. Therefore, sequential mapping of CFAEs and DFs have been used for target sites of AF ablation. However, such mapping strategies are valid only if the CFAEs and DFs are spatiotemporally stable during the mapping procedure. We obtained spatially stable multi-electrode recordings to assess the spatiotemporal stability of CFAEs and DFs. Methods: We recorded electrical activity during AF for 10 min with a 64-electrode basket catheter (48 bipole electrode pairs) placed in the left atrium in 36 patients with AF (paroxysmal AF [PAF], n=16; persistent AF [PerAF], n=20). The spatial and temporal distribution of the CFAEs (fractionation interval 8 Hz) at 1-min intervals for 10 min were compared for each of the 48 bipoles. Results: The baseline CFAEs were located at 68.5±14.0% (32.9±6.7) of the 48 bipoles; however, the high DF sites were fewer (9.6±8.6% [4.6±4.1 bipoles]). The CFAEs sites did not change significantly during the 10-min recording period (kappa statistic: 0.71±0.24); however, the high DF sites changed significantly (kappa statistic: 0.07±0.19). These spatiotemporal changes in the CFAEs and high DFs did not differ between patients with PAF and PerAF. Conclusions: Regardless of the AF type, CFAEs sites, but not high DF sites, showed a high degree of spatial and temporal stability.

Introduction: Acute and mid-term effects of ablation for atrial fibrillation (AF) on left atrial (LA) and left ventricular (LV) function and the atrial electromechanical interval are controversial. Methods: Echocardiographic variables and the PA-TDI interval (time from ECG lead II P-wave onset to lateral a′ wave on tissue Doppler tracings, indicating the total atrial conduction time [TACT]) were evaluated in 33 paroxysmal AF patients before, 1 day, and 3, 6, and 12 months after ablation. Results: During a 12-month follow-up, 10 (30.3%) patients had recurrent AF, associated with a greater baseline LA volume (LAV) (48.4±19.3 mm3 vs. 38.7±11.4 mm3, P=0.0811) and PA-TDI interval (163.9±11.0 ms vs. 151.1±14.6 ms, P=0.0189) than in patients without AF recurrence. By 6 months after ablation, LAV had decreased progressively in the non-recurrence group (27.9±8.1 mm3, P

Background: Electrophysiological characteristics of early repolarization syndrome (ERS), i.e., the spatial and transmural dispersion of ventricular repolarization and ventricular late potentials can be evaluated using a signal-averaged vector-projected 187-channel high-resolution electrocardiogram (187-ch SAVP-ECG). We investigated these characteristics as markers of ventricular fibrillation and sudden cardiac arrest in patients presenting with an ER pattern. Methods: The 187-ch SAVP-ECGs were recorded for 8 patients with idiopathic ventricular fibrillation associated with ERS (ERS patients), and 5 patients with an ER pattern without arrhythmic events (ER pattern patients). Results: The ER pattern was located in the inferior leads (n=7), lateral leads (n=1), or both inferior and lateral leads (n=5). The corrected RT(RTc) (peak point of the R wave − positive maximum peak of the first derivative of the T wave interval corrected using the Bazett formula) interval and T(peak-end)-c interval from the 187 channels were calculated. Late potentials were positive in 7 of 8 ERS patients and in 3 of 5ER pattern patients (P=0.25). The average RTc was shorter in patients with ERS (192.6±29.8 ms vs. 234.0±25.5 ms, P=0.04). However, average T(peak-end)-c interval did not differ between the 2 groups. Conclusion: Late ventricular potentials were common in ERS and ER pattern patients. Lethal arrhythmia in ERS patients appeared to be related to the relatively short average repolarization time rather than the spatial and transmural dispersion of repolarization.

Background: Vector-projected 187-channel electrocardiograms (ECGs) were recorded in 45 patients with a Brugada-type ECG to evaluate spatial and transmural repolarization and dispersion of action potential duration in Brugada syndrome (BS). Methods: Corrected recovery time (RT-c, R wave peak to the first positive maximum derivative of the T wave with Bazett correction) and RT-c dispersion were calculated. The corrected T peak-end interval (T(p-e)-c, T wave peak to the end of the T wave with Bazett correction) and T(p-e)-c dispersion were calculated. Results: RT-c dispersion and T(p-e)-c interval were longer in patients with a type 1 ECG, but there was no significant difference in Tp-e dispersion between patients with a type 1 and those with a type 2/3 ECG. No significant correlation was noted between RT-c dispersion, T(p-e)-c dispersion, and symptoms. Late potentials (P=0.023) and a family history of sudden cardiac death (P=0.0017) were correlated with symptoms. Conclusions: Spatial dispersion of repolarization may constitute the electrocardiographic pattern of the Brugada type ECG and conduction disturbance in addition to repolarization abnormality may contribute to the development of malignant ventricular tachyarrhythmias.

Background: Supernormal conduction (SNC) of the human ventricular myocardium has been reported, but its mechanism remains controversial. Methods: We recorded monophasic action potentials during rapid ventricular pacing from the right ventricular endocardium in 24 patients with supraventricular tachyarrhythmias who underwent catheter ablation. Results: In 7 of 24 patients, shortening of the QRS duration was observed at a pacing cycle length ≤400 ms and lengthening of the QRS duration was observed in 3. Conclusions: Shortening of the QRS duration during rapid ventricular pacing was observed in the patients.

Background: Action potential alternans may be important in causing ventricular arrhythmias. Methods and results: We recorded monophasic action potentials from the right ventricular endocardium in patients with persistent atrial fibrillation who underwent internal atrial defibrillation during rapid ventricular pacing. In 3 of 45 patients, monophasic action potential duration alternans was observed at a pacing cycle length ≤350 ms. Conclusion: Action potential alternans is not a rare phenomenon (6.6%) in humans.

Abstract We describe treatment of atrial flutter and electrical storm presenting as incessant ventricular tachycardia (VT) after implantation of a cardiac resynchronization therapy defibrillator (CRT‐D) in a patient with dilated cardiomyopathy. No prior arrhythmic event had occurred. Our treatment strategy, including amiodarone administration, was guided in part by signal‐averaged vector‐projected 187‐channel electrocardiogram (SAVP‐ECG)‐based risk stratification for ventricular arrhythmia. Corrected recovery time (RTc) dispersion and Tpeak‐end dispersion were used to evaluate transmural dispersion of repolarization. RTc and Tpeak‐end dispersion increased during the period of electrical storm. Values were improved 2 years after CRT‐D implantation, and the amiodarone was discontinued. The VT has not recurred despite discontinuation of the antiarrhythmic agent. SAVP‐ECG‐based risk stratification for ventricular arrhythmia proved useful for the management of antiarrhythmic therapy.

Background: Brugada syndrome is a distinct form of idiopathic ventricular fibrillation. We retrospectively investigated the incidence and clinical implications of supraventricular tachyarrhythmia in patients with Brugada syndrome. Methods: We reviewed 69 consecutive cases of Brugada syndrome, 11 of which had a history of syncope. Results: Seven patients (10.1%) had clinically documented supraventricular tachyarrhythmia: 3 patients with atrioventricular reentrant tachycardia, 2 with atrioventricular nodal reentrant tachycardia, and 2 with paroxysmal atrial fibrillation. The prevalence of a spontaneous type 1 Brugada electrocardiogram and symptoms (history of syncope, presyncope, documented ventricular tachyarrhythmia, or aborted sudden cardiac death) were significantly higher, and QRS duration was significantly longer in patients without than in those with supraventricular tachyarrhythmia. The PR and AH intervals were also longer in patients without than in those with supraventricular tachyarrhythmia, but the differences were not statistically significant. Conclusion: The arrhythmogenic substrate in Brugada syndrome may not be restricted to the ventricles. Palpitations in patients with this syndrome should raise the question of supraventricular tachyarrhythmia. Conversely, in patients with supraventricular tachyarrhythmia and aborted sudden cardiac death or syncope not related to supraventricular tachyarrhythmia, Brugada syndrome should be considered a possible additional electrophysiologic abnormality.

We describe a 49-year-old woman with atrial tachycardia (AT) and arrhythmogenic right ventricular cardiomyopathy/dysplasia. Cardiac magnetic resonance images showed a markedly dilated right atrium and right ventricle. Electroanatomical mapping showed that the AT originated from the right atrial appendage.

Background: Brugada-type ECG changes have been described in association with various cardiac disease states including electrolyte abnormalities, myocardial pathologies, and mechanical cardiac abnormalities as well as drug therapies with particular medications. Such potential confounding factors make it difficult to diagnose Brugada syndrome on the basis of standard guidelines. Methods: To investigate the incidence of significant coronary artery disease in patients with Brugada-type ECG, coronary angiography was performed in 55 patients with Brugada-type ECGs. Results: Five of the 55 patients (9%) had significant coronary artery stenosis, and 3 out of these 5 were asymptomatic. Patients with coronary artery disease were older than in those without coronary artery disease (59.4±7.2 years vs. 49.0±13.8 years, P=0.03). An electrophysiological study was performed in 4 of the 5 patients, and ventricular fibrillation was induced in all 4. Conclusions: We conclude that patients with Brugada-type ECGs should be evaluated for coronary artery disease, and this is especially important for patients in whom age could be a risk factor for the disease.

In this study, the prevalence and prognostic significance of the early repolarization (ER) pattern in the inferolateral leads in patients with Brugada syndrome were investigated. Clinical, genetic, and electrophysiological data were collected and analyzed from 69 individuals with either a spontaneous or drug-induced Brugada type 1 electrocardiogram (ECG) pattern. An ER pattern was defined as J-point elevation at least 0.1 mV from the baseline in at least 2 inferior or lateral leads. The presence of late potentials and inducibility of ventricular fibrillation (VF) by programmed stimulation were compared between patients with and without a J wave. Follow-up data, including outcome events, were obtained for all patients. An ER pattern was observed in the inferolateral leads in 6 patients with a spontaneous Brugada type 1 ECG pattern and in 1 patient with a drug-induced Brugada type 1 ECG pattern. There was no significant intergroup difference in symptoms, family history of sudden cardiac death, prevalence of late potentials, or inducibility of VF. No patient with the ER pattern developed a cardiac event during the mean follow-up period of 73.6±38.1 months. The ER pattern in the inferolateral leads is not uncommon in Brugada syndrome; however, the presence of a J wave does not appear to be associated with subsequent arrhythmic events in patients with Brugada syndrome.

A 73-year-old man with hypertrophic cardiomyopathy was referred for an electrophysiologic study and catheter ablation of premature ventricular contractions (PVCs)/nonsustained ventricular tachycardia (NSVT). The QRS morphology of the PVCs was right bundle branch block with an inferior axis. Transthoracic echocardiography showed left ventricular hypertrophy and a normal left ventricular ejection fraction without any obstruction in the left ventricle (LV). Intracardiac mapping showed that the earliest activation site of the PVCs was within the anterior portion of the basal LV, where a Purkinje potential preceded the QRS onset by 32 ms. Radiofrequency application at that site terminated the PVCs. The PVCs/NSVT did not recur during 10 months of follow-up.

Although the most feared cardiac manifestation in cardiac sarcoidosis is the onset of ventricular arrhythmia, some patients may present with supraventricular arrhythmias. We present a rare case of cardiac sarcoidosis associated with double tachycardia manifesting as atrial flutter and ventricular tachycardia.

We report an interesting case in which atrial fibrillation (AF) was terminated during ablation of high-dominant frequency (DF) sites covered with epicardial adipose tissue (EAT). High-DF sites are known to be related to the center of focal-firing rotors or local reentry circuits. Therefore, this phenomenon suggests that EAT may be related to the development of dominant rotors maintaining AF.

Here, we report a case of a 69-year-old patient with paroxysmal atrial fibrillation and inducible typical atrial flutter who required catheter ablation. After pulmonary vein isolation, cavotricuspid isthmus ablation was performed. During ablation at a lateral site of the cavotricuspid isthmus, a spiky potential appeared at the distal electrode of the ablation catheter, and subsequently, a 2:1 atrioventricular (AV) block occurred. Radiofrequency (RF) delivery at the same site caused a similar phenomenon, implying that the spiky potential may reflect a slow pathway potential as an anatomical variant of the rightward extension of the AV node.