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In adult patients, subcutaneous implantable cardioverter defibrillators (S-ICDs) have been reported to be non-inferior to transvenous ICDs with respect to the incidence of device-related complications and inappropriate shocks. Only a few reports have investigated the efficacy of S-ICDs in the pediatric field. This study aimed to investigate the utility and safety of S-ICDs in patients ≤18 years old.This study was a multicenter, observational, retrospective study on S-ICD implantations. Patients18 years old who underwent S-ICD implantations were enrolled. The detailed data on the device implantations and eligibility tests, incidence of appropriate- and inappropriate shocks, and follow-up data were assessed.A total of 62 patients were enrolled from 30 centers. The patients ranged in age from 3 to 18 (median 14 years old [IQR 11.0-16.0 years]). During a median follow up of 27 months (13.3-35.8), a total of 16 patients (26.2%) received appropriate shocks and 13 (21.3%) received inappropriate shocks. The common causes of the inappropriate shocks were sinus tachycardia (n = 4, 30.8%) and T-wave oversensing (n = 4, 30.8%). In spite of the physical growth, the number of suitable sensing vectors did not change during the follow up. No one had any lead fractures or device infections in the chronic phase.Our study suggested that S-ICDs can prevent sudden cardiac death in the pediatric population with a low incidence of lead complications or device infections. The number of suitable sensing vectors did not change during the patients' growth.

This study sought to assess the performance of current diagnostic criteria and identify additional electrophysiological features differentiating orthodromic reciprocating tachycardia (ORT) with a concealed nodoventricular/nodofascicular (NV/NF) pathway from atrioventricular nodal re-entrant tachycardia (AVNRT).Diagnosing sustained supraventricular tachycardia (SVT) despite the occurrence of ventriculoatrial block (VAB) is challenging.We analyzed electrograms of 25 sustained SVTs (9 NV/NF-ORTs [n = 7/2] and 16 AVNRTs) with VAB and 91 AVNRTs without VAB (for reference).More than 1 SVT, each with a different ventriculoatrial interval, was commonly induced in AVNRT cases (75%) but not in NV/NF-ORT cases (0%; p = 0.0005). Wenckebach VAB was common in NV/NF-ORTs (78%), but VAB patterns varied in AVNRTs. The His-His interval transiently prolonged in the following beat after the VAB in most AVNRTs but rarely did in NV/NF-ORTs (79% vs. 22%; p = 0.01). NV/NF-ORT was diagnosed by His-refractory premature ventricular contractions (n = 5) and the findings during right ventricular overdrive pacing showing an uncorrected/corrected post-pacing interval (PPI)-tachycardia cycle length (TCL) ≤115/110 ms (n = 5/5), orthodromic His capture (n = 6), and V-V-A (ventricle-ventricle-atrial response) response (n = 3). A single form of induced SVT (positive predictive value [PPV]: 69%; negative predictive value [NPV]: 100%), Wenckebach VAB (PPV: 70%; NPV: 87%), stable His-His interval despite VAB (PPV: 70%; NPV: 85%), orthodromic His capture (PPV: 100%; NPV: 97%), and V-V-A response (PPV: 100%; NPV: 95%) characterized NV/NF-ORT, and a PPI-TCL of ≤125 ms (PPV: 100%; NPV: 100%) characterized NV-ORT.Induction of a single SVT form, Wenckebach VAB, stable His-His interval despite VAB, orthodromic His capture, and V-V-A response appeared to discriminate NV/NF-ORT from AVNRT, with a PPI-TCL of ≤125 ms discriminating NV-ORT from NF-ORT and AVNRT.

BACKGROUND Lethal ventricular arrhythmia (VA) can be initiated by idiopathic premature ventricular contractions (PVCs) originating from the left ventricular (LV) inferior wall. Furthermore, J-wave elevation in the inferior leads on ECG is sometimes associated with lethal VA. However, the relationship between these PVCs and J-wave elevation in patients with lethal VA is unclear, so we investigated it in the present study.Methods and Results:We studied 32 consecutive patients who underwent radiofrequency (RF) ablation of idiopathic PVCs with right bundle branch block (RBBB) and superior axis. Thee PVCs were originating from the inferior wall of the LV. Lethal VA was defined as ventricular fibrillation (VF) or ventricular tachycardia (VT) with loss of consciousness (LOC). Among 32 patients, 3 had VF and 2 had VT with LOC. Other 27 had non-lethal VA. Baseline clinical characteristics were not significantly difference between lethal and non-lethal VA. The ratio of J-wave elevation in lethal VA was significantly higher as compared with non-lethal VA (100% vs. 11.1%, P

Background There are some controversial reports related to the pro‐arrhythmic or anti‐arrhythmic potential of cardiac resynchronization therapy (CRT) and little is known about the relationship between ventricular arrhythmia (VA) and left ventricular (LV)‐lead threshold. Hypothesis Upgrade CRT is anti‐arrhythmic effect of VA with implantable cardioverter‐defibrillator (ICD) patients and has a relationship with the incident of VA and LV‐lead threshold. Methods Among 384 patients with the implantation of CRT‐defibrillator (CRT‐D), 102 patients underwent an upgrade from ICD to CRT‐D. We divided patients into three groups; anti‐arrhythmic effect after upgrade (n = 22), pro‐arrhythmic effect (n = 14), and unchanging‐VA events (n = 66). The VA event was determined by device reports. We described the electrocardiography parameters, LV‐lead characteristics, and clinical outcomes. Results Before upgrade, the numbers of VA were 305 episodes and the numbers of ICD therapy were 157 episodes. While after upgrade, the numbers of VA were 193 episodes and the number of ICD therapy were 74 episodes. Ventricular tachycardia cycle length (VT‐CL) after upgrade was significantly slower as compared to those with before upgrade. Pro‐arrhythmic group was significantly higher with delta LV‐lead threshold (after 1 month—baseline) as compared to those with anti‐arrhythmic group (0.74 vs −0.21 V). Furthermore, pro‐arrhythmic group was significantly bigger with delta VT‐CL (after 3 months—before 3 months) as compared to those with anti‐arrhythmic group (P = .03). Conclusions We described upgrade‐CRT was associated with reduction of VA, ICD therapies and VT‐CL. While 14 patients had a pro‐arrhythmic effect and LV lead threshold might be associated with VA‐incidents.

Background Atrial fibrillation (AF) is a leading preventable cause of heart failure (HF) for which early detection and treatment is critical. Subclinical-AF is likely to go untreated in the routine care of patients with cardiac resynchronization therapy defibrillator (CRT-D). Hypothesis The hypothesis of our study is that subclinical-AF is associated with HF hospitalization and increasing an inappropriate therapy. Methods We investigated 153 patients with an ejection fraction less than 35%. We divided into three groups, subclinical-AF (n = 30), clinical-AF (n = 45) and no-AF (n = 78). We compared the baseline characteristics, HF hospitalization, and device therapy among three groups. The follow-up period was 50 months after classification of the groups. Results The average age was 66 ± 15 years and the average ejection fraction was 26 ± 8%. Inappropriate therapy and biventricular pacing were significantly different between subclinical-AF and other groups (inappropriate therapy: subclinical-AF 13% vs clinical-AF 8.9% vs no-AF 7.7%: P = .04, biventricular pacing: subclinical-AF 81% vs clinical-AF 85% vs no-AF 94%, P = .001). Using Kaplan-Meier method, subclinical-AF group had a significantly higher HF hospitalization rate as compared with other groups. (subclinical-AF 70% vs clinical-AF 49% vs no-AF 38%, log-rank: P = .03). In multivariable analysis, subclinical-AF was a predictor of HF hospitalization. Conclusions Subclinical-AF after CRT-D implantation was associated with a significantly increased risk of HF hospitalization. The loss of the biventricular pacing and increasing an inappropriate therapy might affect the risk of HF hospitalization.

Background Lethal-ventricular-arrhythmia (VA) could be sometimes initiated by idiopathic Premature Ventricular Contractions (PVCs) originated form inferior wall. Furthermore, J-wave elevation in inferior leads was sometimes associated with lethal-VA. However, it was unclear the relationship between these PVCs and J-wave elevation in patients with lethal-VA. Purpose The aim of this study was to investigate the relationship between PVCs and J-wave elevation. Methods and results We studied 32 patients who underwent radiofrequency (RF) ablation of idiopathic PVCs with RBBB and superior axis. These PVCs were originating from inferior wall of left ventricular. Lethal-VA was defined as ventricular fibrillation (VF) or ventricular tachycardia (VT) with loss of consciousness (LOC). Among 32 patients, 3 had VF and 2 had VT with LOC. Other 27 had non-lethal-VA. Baseline clinical characteristics were not significantly difference between lethal and non-lethal-VA. The ratio of J-wave elevation in lethal-VA was significant higher as compared to those with non-lethal-VA (5/5 (100%) vs. 3/27 (11.1%), p Conclusions We speculated that J-wave elevation in inferior leads might be a predictor of lethal-VA initiated by PVCs with RBBB and superior axis. RF ablation of these PVCs were useful method of treating lethal-VA. Acknowledgement/Funding None

Background: Pulmonary vein isolation (PVI) via catheter ablation has been shown to be a highly effective treatment option for patients with symptomatic paroxysmal atrial fibrillation (AF). The recurrence of AF within 3 months after PVI is not considered to be the result of ablation procedure failure, because early recurrence of AF is not always associated with late recurrence. We examined the usefulness of an external loop recorder with an auto-trigger function (ELR-AUTO) for the detection of atrial fibrillation following PVI to characterize early recurrence and to determine the implications of AF occurrence within 3 months after PVI. Methods: Fifty-three consecutive symptomatic patients with paroxysmal AF (age 61.6±12.6 years, 77% male) who underwent PVI and were fitted with ELR-AUTO for 7±2.0 days within 3 months after PVI were enrolled in this study. Results: Of the 33 (62.2%) patients who did not have AF recurrence within 3 months after PVI, only 1 patient experienced AF recurrence at 12 months. Seven (35%) of the 20 patients who experienced AF within 3 months of PVI experienced symptomatic AF recurrence at 12 months. The sensitivity, specificity, positive predictive value, and negative predictive value of early AF recurrence for late recurrence were 87.5%, 71.1%, 35.0%, and 96.9%, respectively. Conclusions: AF recurrence measured by ELR-AUTO within 3 months after PVI can predict the late recurrence of AF. Freedom from AF in the first 3 months following ablation significantly predicts long-term AF freedom. ELR-AUTO is useful for the detection of symptomatic and asymptomatic AF.

BACKGROUND Syncope is a common occurrence. The presence of J-wave, also known as early repolarization, on electrocardiogram is often seen in the general population, but the relationship between syncope and J-wave is unclear. METHODS AND RESULTS After excluding 67 patients with structural heart disease from 326 with syncope, we classified 259 patients according to the presence or absence of J-wave (≥1 mm) in at least 2 inferior or lateral leads. Head-up tilt test (HUT) was performed for 30 min. If no syncope or presyncope occurred, HUT was repeated after drug loading. Before tilt, 97/259 (37%) had J-wave (57 male, 47.6±22.5 years) and 162 patients had no remarkable change (89 male, 51.1±21.2 years). HUT-positive rate was higher in patients with J-wave, compared with patients without (P

Background: Head-up tilt (HUT) testing is used to establish the diagnosis of neurally mediated syncope (NMS). Adenosine administration during HUT testing is useful for inducing NMS. However, no comparison between adenosine HUT testing and HUT testing using other drugs has been reported. The purpose of this study was to investigate the clinical usefulness of adenosine compared with isoproterenol (ISP) and isosorbide (ISDN) during HUT testing. Methods: The subjects comprised 103 consecutive patients with unexplained syncope who underwent adenosine and isoproterenol (ISP) HUT tests following a negative response in a drug-free HUT test. Subjects were first tilted upright at an 80° angle for 30 min and shown to have a negative response in drug-free HUT test. Subsequently, a continuous bolus of 0.1- or 0.2-mg/kg adenosine was administered while the subjects remained upright and were observed for 5 min (adenosine HUT test). Next, they were tilted upright for 15 min during a continuous infusion of 0.01–0.02 mg/kg min ISP (ISP HUT test). Lastly, they were tilted upright for 15 min after 1.25-mg ISDN infusion (ISDN HUT test). Results: The diagnostic yield of the adenosine HUT test was 18.1% (18/99) and that of the ISP HUT test was 6.0% (6/99; p=N.S.). Sixty-one of 99 patients underwent ISDN HUT testing, and 17 patients had a positive response. The diagnostic yield of the adenosine HUT test was 14.7% (9/61) and that of ISDN HUT test was 27.8% (p

BACKGROUND Predictors of poor outcomes remain unknown for cardiovascular syncope patients after discharge.Methods and Results:We reviewed the medical records of consecutive patients admitted to hospital with cardiovascular syncope. We then performed Cox stepwise logistic regression analysis to identify significant independent factors for death, rehospitalization for syncope, and cardiovascular events. The study group was 206 patients with cardiovascular syncope. Of them, bradycardia was diagnosed in 50%, tachycardia in 27%, and structural disease in 23%. During a 1-year follow-up period, 18 (8%) and 45 (23%) patients, respectively, were rehospitalized for syncope or a cardiovascular event, and 10 (4%) died. Independent predictors of cardiovascular events were systolic blood pressure

Introduction We investigated the efficacy of carvedilol for preventing the recurrence of atrial fibrillation and reducing QT prolongation induced by bepridil. Methods We assigned 144 subjects with persistent atrial fibrillation. The subjects were divided into 3 groups: carvedilol plus bepridil, candesartan plus bepridil, and bepridil alone. The primary endpoint was length of time to the recurrence of atrial fibrillation. All subjects were followed up for 3 years. Electrocardiographic parameters were measured for QT interval, QTc, heart rate, and QRS duration. Results The pharmacological conversion rate by carvedilol plus bepridil was 77%, candesartan plus bepridil was 63%, and bepridil alone was 57%. The significant difference was between carvedilol plus bepridil and bepridil alone (P = 0.03). The maintenance of SR at 3 years was 60% in carvedilol plus bepridil, 59% in candesartan plus bepridil, and 40% in bepridil alone. The difference between carvedilol plus bepridil and bepridil alone was statistically significant (P = 0.04). QTc and QT interval were significantly prolonged in candesartan plus bepridil and bepridil alone but not in carvedilol plus bepridil. Conclusions The authors demonstrated that the combination therapy with carvedilol plus bepridil is more effective for maintaining SR than bepridil alone therapy and carvedilol reduced QT prolongation by bepridil therapy.

Background: Long-term right ventricular apical (RVA) pacing increases the risk of heart failure (HF) by inducing ventricular dyssynchronization. Although recent studies suggest that right ventricular septal (RVS) pacing results in improved short-term outcomes, its long-term effectiveness remains unclear. Methods and results: This study investigated 149 consecutive patients who underwent implantation of a dual chamber pacemaker for atrioventricular block with either RVS-pacing between July 2007 and June 2010 or RVA-pacing between January 2003 and June 2007. The endpoint was defined as death and hospitalization due to heart failure (HF). The rates of mortality and hospitalization due to HF were significantly lower in the RVS-pacing group than that in the RVA-pacing group (event free RVS: 1 year, 98% and 2 years, 98%; RVA: 1 year, 85% and 2 years, 81%; p

Background Left atrial–esophageal fistulas (LAEFs) are serious complications with high mortality after atrial fibrillation radiofrequency ablation (AFRA). Decreasing the incidence of esophageal thermal lesions (EsoTLs) that may lead to LAEFs is important. The aim of this study was to suppress EsoTL development and determine the appropriate alarm setting for a temperature-monitoring probe by using steerable sheath (STS) methods. Methods We enrolled 82 consecutive patients (mean, 61.9±11.7 years; 75.6% men) who underwent AFRA, including pulmonary vein isolation for symptomatic, drug-refractory atrial fibrillation with esophageal temperature monitoring by using STS between January 2011 and April 2014. All patients underwent upper gastrointestinal endoscopy (UGE) 1–3 days after AFRA. The timing of ablation discontinuation in the first 17 patients was determined by each physician during AFRA (only monitoring group, OM). In the next 65 patients, physicians were to immediately discontinue ablation when an alarm set at 39°C went off (instruction group, INS). We compared two groups with respect to the incidence of EsoTLs. Results Among the 82 patients, 5 (6.1%) had EsoTLs after AFRA. EsoTLs occurred in 3 of 17 patients (17.6%) and 2 of 65 patients (3.1%) in the OM and INS groups, respectively. The incidence of EsoTLs in the INS group was significantly lower than that in the OM group ( p =0.0254). EsoTL did not occur at maximal temperature less than 39°C, measured by using esophageal temperature-monitoring probe. Conclusions Immediate discontinuation of ablation during pulmonary vein isolation remarkably decreased the incidence of EsoTLs, even when using STS.

Background and purpose The present diagnostic method and features of syncope in Japan are unclear. Implantable loop recorder (ILR) and head-up tilt tests have recently become available for diagnosing syncope. The examination method and rates of diagnosing syncope may vary. This study aimed to clarify the present diagnostic method and features of syncope in a single Japanese medical center. Methods and results We retrospectively reviewed the medical records of consecutive patients who were seen at our hospital from January 1, 2009, to December 31, 2012. A total of 547 patients (328 men, 60.4 ± 21.5 years) with syncope were seen at our hospital. Reflex syncope was diagnosed in 29.1% of the cases, orthostatic hypotension in 11.7%, cardiac syncope in 34.0%, and unexplained syncope in 23.9% by initial and early evaluations. The number of patients with situational syncope and orthostatic hypotension that could be diagnosed in the initial evaluation of the first examination was significantly greater than that in subsequent evaluations. Forty-three percent of the unexplained syncope patients received an ILR. The consent rate for ILR implantations in the unexplained syncope patients with a suspected arrhythmia nature was 53.1%. The cumulative ILR diagnostic rates were 47% and 65% at 1 and 2 years after the ILR implantation, respectively. The estimated ILR diagnostic rates were significantly greater than that for conventional test without using an ILR. When patients with unexplained syncope could be diagnosed, the recurrent symptoms were greatly reduced. Conclusions Syncope is induced by various causes in Japan. It is important that we understand the characteristics of each syncope cause. The consent rate for implanting an ILR in appropriate unexplained syncope patients is low. We need to educate these patients about the importance of making a diagnosis of syncope.

Fibrosis and inflammation may play a significant role in the pathogenesis of atrial fibrillation (AF) recurrence. Type III procollagen-N-peptide (PIIINP) may be related to atrial fibrosis and play a role in predicting the recurrence of AF. We investigated whether PIIINP as a fibrosis marker predicts the recurrence of AF after cardioversion.Serum PIIINP, interleukin-6, high-sensitivity C-reactive protein, brain natriuretic peptide, renin and aldosterone were measured at baseline and 24 months in 88 patients (62%) with sinus rhythm (SR) maintenance and 54 patients (38%) with AF recurrence. Furthermore, the root mean square voltage in the last 20 ms (RMS20) via P-wave signal-averaged electrocardiogram (P-SAECG) was measured and the relationship between fibrosis biomarkers and RMS20 was examined. Baseline PIIINP with AF recurrence was significantly higher than for those with SR maintenance (0.664 vs. 0.581 U/mL, P = 0.001). However, there were no significant differences in other biomarkers. A logistic regression identified PIIINP (odds ratio 2.61, P = 0.008) as an independent predictor of AF recurrence. The RMS20 as measured by P-SAECG with SR maintenance and PIIINP levels0.72 U/mL (at baseline) was significantly higher after 24 months than at baseline. Furthermore, the RMS20 with AF recurrence and PIIINP levels0.72 U/mL (at baseline) was significantly lower after 24 months than baseline.Elevated baseline PIIINP concentration is an independent predictor for AF recurrence after cardioversion. Furthermore, there is a relationship between PIIINP and RMS20 and the fibrosis of AF.

A 61 years old man admitted for catheter ablation for persistent atrial fibrillation (AF), lasting 18 months, which was resistant to aprindine and bepridil. At the catheter ablation, complex fractionated atrial electrograms (CFAEs) were mapped on the electroanatomical map merged with computed tomography using CARTO XP system (Johnson & Johnson). Radio frequency ablation was performed to the point of CFAEs in left atrium, but AF was persisting after CFAEs were decreased especially. Then, ablate for electrograms like action potential firing from high right atrium and inside of coronary sinus, AF changed into atrial tachycardia (AT) on which the earliest action potential started from high right atrium. Put Lasso catheter in superior vena cava (SVC), there was action potential firing in front side of SVC. AT terminated during ablation of action potential firing in front side of SVC, but AT repeated with firing electrograms from almost same site of SVC. After several times ablation to firing site of SVC, both AF and AT did not recur and they could not be induced.

Background: The impact of cardiac resynchronization therapy (CRT) on dispersion of repolarization is controversial. This study aimed to determine whether CRT alters the QT interval and Tpeak–Tend interval (Tpeak–end) and whether such changes relate to the risk of developing a major arrhythmic event (MAE). Methods: Data from 67 patients (49 men; age 71±10 years) who underwent CRT device placement were analyzed retrospectively. Patients had NYHA class III or IV heart failure. Mean left ventricular ejection fraction was 25±9%. The electrocardiogram was recorded at baseline and during follow-up after implantation (3 days, 7 days, 1 month, and 2 months). Results: After 29-months of follow-up, 11 patients had experienced MAEs. QT interval and Tpeak–end did not change significantly immediately after CRT. However, 3 days after CRT, Tpeak–end in patients with MAE was significantly increased when compared with patients without MAE (p