Prolonged T-peak to T-end Interval Predicts Implantable Cardioverter Defibrillator Therapy in Patients With Cardiac Sarcoidosis.

BACKGROUND: The association between the T-peak to T-end interval (Tp-e) and ventricular arrhythmia (VA) events in cardiac sarcoidosis (CS) is unknown. The purpose of this study was to investigate whether Tp-e was associated with VA events in CS patients with implantable cardioverter defibrillators (ICDs) or cardiac resynchronization therapy defibrillators (CRT-Ds).Methods and Results: We retrospectively studied 50 patients (16 men; mean [±SD] age 56.3±10.5 years) with CS and ICD/CRT-D. The maximum Tp-e in the precordial leads recorded by a 12-lead electrocardiogram after ICD/CRT-D implantation was evaluated. The clinical endpoint was defined as appropriate ICD therapy. During a median follow-up period of 85.0 months, 22 patients underwent appropriate therapy and 10 patients died. Kaplan-Meier analysis revealed that the probability of the clinical endpoint was 28.3% at 2 years and 35.3% at 4 years. The optimal cut-off value of the Tp-e for the prediction of the clinical endpoint was 91 ms, with a sensitivity of 72.7% and a specificity of 87.0% (area under the curve=0.81). Multivariate Cox regression analysis showed that Tp-e ≥91 ms (hazard ratio [HR] 5.10; 95% confidence interval [CI] 1.99-13.1; P<0.001) and a histological diagnosis of CS (HR 3.84; 95% CI 1.28-11.5; P=0.016) were significantly associated with the clinical endpoint. CONCLUSIONS: Tp-e ≥91 ms was a significant predictor of VA events in patients with CS and ICD/CRT-D.

Lead switching to resolve undersensing of ventricular tachycardia by a cardiac resynchronization therapy defibrillator.

A 63-year-old man was admitted to the hospital due to ventricular tachycardia (VT) undersensing, caused by decreased R-wave amplitude in a cardiac resynchronization therapy defibrillator. The R-wave amplitude of VT sensed by the left ventricular (LV) lead was markedly higher than that by the right ventricular (RV) lead; therefore, we reconnected the IS-1 RV lead to the LV IS-1 port and the IS-1 LV lead to the RV IS-1 port to resolve this issue. After discharge, it was confirmed that VT was successfully terminated by the second sequence of intrinsic ATP (iATP, Medtronic, Minneapolis, MN, USA) from the LV lead.

Impact of the timing of first appropriate shock on outcomes in patients with an implantable cardioverter-defibrillator: Early versus late.

BACKGROUND: Appropriate implantable cardioverter-defibrillator (ICD) shocks are associated with an increased risk of mortality and heart failure (HF) events. The first appropriate shock may occur late after implantation. However, whether the timing of the first appropriate shock influences prognosis is unknown. This study aimed to evaluate the clinical significance of the timing of the first appropriate shock in patients with ICD. METHODS: This retrospective and observational study enrolled 565 consecutive ICD patients. Patients who received an appropriate shock were divided into the early group (first appropriate shock <1 year after ICD implantation) and late group (first appropriate shock ≥1 year after ICD implantation). All-cause mortality was compared between the two groups. RESULTS: Over a median follow-up of 5.6 years, 112 (19.8%) patients received an appropriate shock, including 32 patients (28.6%) in the early group and 80 patients (71.4%) in the late group. Comparisons of baseline characteristics at ICD implantation revealed that the late group was more likely to receive cardiac resynchronization therapy (66.3% vs. 31.3%, p < 0.001), ICD for primary prevention (60.0% vs. 31.3%, p = 0.001), and angiotensin-converting enzyme inhibitor or angiotensin-receptor blocker treatment (88.8% vs. 71.9%, p = 0.028). Survival after shock was significantly worse in the late group than in the early group (p = 0.027). In multivariable Cox proportional hazards analysis, the late group had an increased risk of all-cause mortality compared with the early group (HR: 2.22; 95% CI 1.01-4.53; p = 0.029). In both groups, the most common cause of death was HF. CONCLUSIONS: Late occurrence of the first appropriate ICD shock was associated with a worse prognosis compared with early occurrence of the first appropriate shock. Cardiac death was the most common cause of death in patients who experienced late occurrence of the first appropriate ICD shock, resulting from HF in most cases.

Prognostic significance of cardiorenal dysfunction within 1 year after atrial fibrillation ablation in patients with systolic dysfunction.

Atrial fibrillation (AF) ablation can improve left ventricular ejection fraction (LVEF) and renal function and can even reduce mortality in patients with impaired LVEF. However, the effect of post-ablation cardiorenal dysfunction on the prognosis of patients with impaired LVEF who underwent AF ablation remains unclear. Of the 1243 consecutive patients undergoing AF ablation, the prognosis of 163 non-dialysis patients who underwent AF ablation with < 50% LVEF was evaluated. The primary outcome was a composite of all-cause mortality, heart failure hospitalization, and a need for modification of the treatment for heart failure. During the median follow-up of 4.2 years after the first AF ablation procedure, the primary outcome occurred in 30 of 163 patients (18%). The receiver operating characteristic curve analysis demonstrated that the post-LVEF (LVEF within 1 year after the procedure, and before the occurrence of primary outcome) had larger areas under the curve (0.70) than the pre-LVEF (LVEF before the procedure), and the most optimal cutoff value was LVEF ≤ 42%. Multivariate analysis demonstrated that patients with post-LVEF ≤ 42% and worsening renal function (WRF; an absolute increase in serum creatinine [SCr] ≥ 0.3 mg/dL compared with the SCr at baseline within 1 year after the procedure and before the occurrence of primary outcome) had a 3.4- to 4.3-fold and 3.4- to 3.7-fold higher risk of the primary outcome compared with those without these predictors, respectively. Patients were categorized using post-LVEF ≤ 42% and WRF as follows: group 1 (post-LVEF > 42% without WRF), group 2 (post-LVEF ≤ 42% without WRF), group 3 (post-LVEF > 42% with WRF), and group 4 (post-LVEF ≤ 42% with WRF). Group 4 had a 15.8-fold (P = 0.0001) higher risk of the primary outcome compared with group 1 after adjusting for pre-procedural factors. In patients with impaired LVEF undergoing AF ablation, post-LVEF ≤ 42% and WRF were independent predictors of poor prognosis. The combination of post-LVEF ≤ 42% and WRF is strongly associated with a poor prognosis in patients with AF undergoing ablation, who with these post-ablation cardiorenal dysfunction may have to be treated more intensively after AF ablation.

Technical Features and Clinical Outcomes of Coronary Venous Left Ventricular Lead Removal and Reimplantation.

BACKGROUND: The number of patients undergoing cardiac resynchronization therapy has increased. Consequently, there is increased frequency in the removal and reimplantation of coronary venous (CV) leads due to infection or malfunction.Methods and Results:A total of 345 consecutive patients referred for lead(s) extraction were reviewed. Of these, 34 patients who underwent a CV lead removal were investigated. The indications for CV leads removal were device-related infections in 29 patients and lead malfunctions in 5 patients. The average duration of the CV leads was 4.1±3.8 years. All CV leads were successfully removed without any major complications, except for 1 in-hospital death. Successful CV lead removal by simple traction (ST) was achieved in 21 patients (62%), whereas extraction tools were required in 13 patients (38%). Local infection and CV lead dwell time were significantly associated with successful ST (P=0.04 and P=0.014, respectively). CV lead re-implantation was successfully performed in 25 patients; however, a right-side approach was required in 92%, and occlusion/stenosis of the previous CV was observed in 80% of the patients. CONCLUSIONS: CV lead removal is relatively successful and safe. The presence of local infection and a shorter lead duration may enable successful ST of a CV lead. However, the re-implantation procedure should be well prepared for the complexity related to the right-side approach and occlusion/stenosis of the previous CV.

Left intraventricular pressure gradient in hypertrophic cardiomyopathy patients receiving implantable cardioverter-defibrillators for primary prevention.

BACKGROUND: Conventional risk factors for sudden cardiac death (SCD) justify primary prevention through implantable cardioverter-defibrillator (ICD) implantation in hypertrophic cardiomyopathy (HCM) patients. However, the positive predictive values for these conventional SCD risk factors are low. Left ventricular outflow tract obstruction (LVOTO) and midventricular obstruction (MVO) are potential risk modifiers for SCD. The aims of this study were to evaluate whether an elevated intraventricular pressure gradient (IVPG), including LVOTO or MVO, is a potential risk modifier for SCD and ventricular arrhythmias requiring ICD interventions in addition to the conventional risk factors among HCM patients receiving ICDs for primary prevention. METHODS: We retrospectively studied 60 HCM patients who received ICDs for primary prevention. An elevated IVPG was defined as a peak instantaneous gradient ≥ 30 mmHg at rest, as detected by continuous-wave Doppler echocardiography. The main outcome was a composite of SCD and appropriate ICD interventions, which were defined as an antitachycardia pacing or shock therapy for ventricular tachycardia or fibrillation. The Cox proportional hazards model was used to assess the relationships between risk factors and the occurrence of SCD and appropriate ICD interventions. RESULTS: Thirty patients met the criteria of elevated IVPG (50%). During the median follow-up period of 66 months, 2 patients experienced SCD, and 10 patients received appropriate ICD interventions. Kaplan-Meier curves showed that the incidence of the main outcome was higher in patients with an IVPG ≥ 30 mmHg than in those without an IVPG ≥ 30 mmHg (log-rank P = 0.03). There were no differences in the main outcome between patients with LVOTO and patients with MVO. The combination of nonsustained ventricular tachycardia (NSVT) and IVPG ≥ 30 mmHg was found to significantly increase the risk of the main outcome (HR 6.31, 95% CI 1.36-29.25, P = 0.02). Five patients experienced ICD implant-related complications. CONCLUSIONS: Our findings showed that a baseline IVPG ≥ 30 mmHg was associated with an increased risk of experiencing SCD or appropriate ICD interventions among HCM patients who received ICDs for primary prevention. Combined with NSVT, which is a conventional risk factor, a baseline IVPG ≥ 30 mmHg may be a potential modifier of SCD risk in HCM patients.

Feasibility of superior vena cava isolation in patients with cardiac implantable electronic devices.

INTRODUCTION: Some patients with cardiac implantable electronic devices (CIEDs) require atrial fibrillation (AF) ablation, and the superior vena cava (SVC) has been identified as one of the most common non-pulmonary vein foci of AF. This study aimed to investigate the interaction between SVC isolation (SVCI) and CIED leads implanted through the SVC. METHODS AND RESULTS: We studied 34 patients with CIEDs who had undergone SVCI as part of AF ablation (CIED group), involving a total of 71 CIED leads. A similar number of age-, sex-, and AF type-matched patients without CIEDs formed a control group (non-CIED group). Patients' background and procedural characteristics were compared between the groups. In the CIED group, lead parameters before and after AF ablation were compared, and lead failure after AF ablation was also examined in detail. Procedural characteristics other than fluoroscopic time were similar in both groups. The success rate of SVCI after the final ablation procedure was 91.2% in the CIED group and 100% in the non-CIED group; however, these differences were not statistically significant. Lead parameters before and after the AF ablation did not significantly differ between the two groups. Lead failure was observed in three patients, with a sensing noise in one patient and an impedance increase in two patients after SVCI. CONCLUSION: SVCI was achievable without lead failure and significant change in lead parameters in most patients with CIEDs; however, it should be noted that lead failure was observed in 8.8% of the study patients after SVCI.

Comparison of high-power and conventional-power radiofrequency energy deliveries in pulmonary vein isolation using unipolar signal modification as a local endpoint.

INTRODUCTION: Negative component abolition of the unipolar signal (unipolar signal modification [USM]) reflects the lesion transmurality. The purpose of this study was to compare the procedural safety and outcome between high-power and conventional-power atrial radiofrequency applications during a pulmonary vein isolation (PVI) using USM as a local endpoint. METHODS AND RESULTS: High-power (50 W) and conventional-power (25-40 W) applications were compared among 120 consecutive patients with paroxysmal atrial fibrillation who underwent a USM-guided PVI. The first 60 patients were treated with conventional-power (CP) group and last 60 with high-power (HP) group. The atrial radiofrequency applications lasted for 5 to 10 seconds (CP group) or 3 to 5 seconds (HP group) after the USM. All procedures were performed using 3D mapping systems with image integration and esophageal temperature monitoring. The baseline characteristics were similar between the two groups. The HP group had fewer acute PV reconnections (62% vs 78%; P = .046) and a reduced procedure time (119.3 ± 28.1 vs 140.1 ± 51.2 minutes; P = .04). Freedom from recurrence after a single ablation procedure without any antiarrhythmic drugs was higher in the HP group than CP group (88.3% vs 73.3% at 12-months after the procedure, log-rank; P = .0423). There were no major complications that required any intervention. CONCLUSIONS: The high-power PVI guided by USM decreased the procedural time and may improve the procedural outcomes without compromising the safety.

Right atrial conduction time for predicting coexistent typical atrial flutter in patients with paroxysmal atrial fibrillation.

INTRODUCTION: Screening of coexistent typical atrial flutter (AFL) in patients with atrial fibrillation (AF) is sometimes challenging. This study investigated whether a prolonged right atrial conduction time (RACT) estimated by tissue Doppler imaging (TDI) predicts patients with concomitant AFL and AF. METHODS AND RESULTS: We retrospectively analyzed 398 patients (mean age: 61.6 years, 73.4% men) undergoing catheter ablation of paroxysmal AF. The patients were classified into two groups according to whether they had evidence of AFL (N = 122, 30.7%) determined by a clinical observation (N = 68), induction during procedures (N = 33), or AFL recurrence after procedures (N = 21) or not (N = 276, 69.3%). The preoperative RACT, defined as a longer duration between the onset of the P-wave and peak A'-wave on the right atrial lateral wall or septal wall, and total atrial conduction time (TACT), defined as the same time duration on the left atrial lateral wall, were evaluated in all patients. Patients with evidence of AFL had a significantly longer RACT than those without AFL (p < .001). A multiple logistic regression and receiver operator characteristics curve analysis revealed the ratio of the RACT and TACT (RACT/TACT) was the independent and most superior accurate cofounder for predicting evidence of AFL (area under the curve: 0.867). When adding a discriminator of an RACT/TACT ≧ 93% into the conventional screening, 98.4% of the patients with evidence of AFL were estimated to be treated during the initial procedures. CONCLUSION: The estimated RACT/TACT using the TDI may be useful for predicting patients with concomitant AFL in patients with AF.

Safety and efficacy of transvenous lead extractions for noninfectious superfluous leads in a Japanese population: A single-center experience.

BACKGROUND: A challenging decision exists as whether to abandon or remove noninfectious superfluous leads during lead revisions or cardiac implantable electronic device (CIED) upgrades. There is insufficient data in the Asian population to guide decision making. METHODS: This study investigated the safety and efficacy of transvenous lead extractions (TLEs) in a high-volume Japanese center. Among a total of 341 patients who underwent lead revisions or CIED upgrades between 2008 and 2018, 53 patients (16%) who underwent TLEs to remove the superfluous leads were analyzed. RESULTS: Indications for TLE were vascular issues (60%), recalled leads (21%), growth of the body size (6%), abandoned leads in young patients (6%), switch to a subcutaneous implanted cardiac defibrillator (4%), need for an MRI conditional CIED (2%), and risks of vascular injury (2%). The population included 29 patients (55%) with nonfunctional leads and 24 (45%) with functional abandoned leads. A total of 74 target leads (mean 1.4 leads/person, median lead age 6.7 years) were extracted with a complete removal achieved in 98%. All coexisting leads, intended for continued use, were not damaged. All new leads (mean 1.4 leads/person) that had been simultaneously implanted during the TLE procedures were successfully implanted. There was one minor complication (2%) involving a pericardial effusion but it did not affect the hemodynamics. CONCLUSIONS: In this Japanese single center experience, the removal of noninfectious superfluous leads with TLEs seemed to be a safe and effective therapeutic option.

Occurrence of Potentially Lethal Arrhythmia due to Sudden Exposure of an Overt Accessory Pathway 8 Years After Catheter Ablation of a Concealed Accessory Pathway.

Although the efficacy of catheter ablation of the accessory pathway (AP) has been established, there are subgroups of APs with an intermittent conduction property, which is sometimes difficult to diagnose accurately. A 57-year-old man with a history of catheter ablation was referred to our clinic due to frequent faintness. He had undergone concealed AP ablation 8 years previously and bilateral circumferential pulmonary vein isolation (CPVI) 6 years previously. During regular electrocardiogram monitoring, it was suggested that irregular wide QRS tachycardia, which was considered to be atrial fibrillation with antegrade AP conduction, was the cause of the present symptoms. In the present electrophysiological study, we noticed a residual antegrade AP in the left lateral wall that was not observed during the previous session. We achieved abolition of overt accessory conduction, bilateral CPVI, and superior vena cava isolation with several radiofrequency applications without any recurrence. We also confirmed the absence of dormant conduction in the AP and the left atrium-PV connection with 20 mg adenosine triphosphate. This case demonstrated the possibility of sudden exposure of overt AP conduction late after catheter ablation of the concealed AP and the importance of confirming the absence of dormant conduction by means of adenosine triphosphate, which has the potential benefit of revealing latent AP conduction.

Cause of the "power-on reset" phenomenon other than electric magnetic interference in a patient with a pacemaker.

A 67-year old male with a dual-chamber pacemaker visited for a regular check-up. An unfamiliar message emerged on the display just after placing the programmer wand. We could recognize that the pacemaker had already been in the safe back-up mode of DDI, and the programmer prompted a re-initialization request. We are so surprised because there was no indication of device malfunction the day before in daily monitoring and a 12-lead electrocardiogram revealed normally working in the DDD mode just before checking the device. The pacemaker was immediately re-programmed to the former setting. This phenomenon has not recurred for 12 months.

Applicability of 3-Dimensional Quantitative Coronary Angiography-Derived Computed Fractional Flow Reserve for Intermediate Coronary Stenosis.

BACKGROUND: Quantitative flow ratio (QFR) is a newly developed image-based index for estimating fractional flow reserve (FFR).Methods and Results:We analyzed 151 coronary arteries with intermediate stenosis in 142 patients undergoing wire-based FFR measurement using dedicated software. Predefined contrast flow QFR, which was derived from 3-dimensional quantitative coronary angiography (3-D QCA) withThrombolysis in Myocardial Infarction (TIMI) frame counts, was compared with FFR as a reference. QFR had good correlation (r=0.80, P<0.0001) and agreement (mean difference: 0.01±0.05) with FFR. After applying the FFR cut-off ≤0.8, the overall accuracy rate of QFR ≤0.8 was 88.0%. On receiver operating characteristics analysis, the area under the curve was 0.93 for QFR. In contrast, 3-D QCA-derived anatomical indices had insufficient correlation with FFR and diagnostic performance compared with QFR. CONCLUSIONS: QFR had good correlation and agreement with FFR and high diagnostic performance in the evaluation of intermediate coronary stenosis, suggesting that QFR may be an alternative tool for estimating myocardial ischemia.

Multiple focal and macroreentrant left atrial tachycardias originating from a spontaneous scar at the contiguous aorta-left atrium area in a patient with hypertrophic cardiomyopathy: a case report.

BACKGROUND: Spontaneous scar-related left atrial tachycardia (AT) is a rare arrhythmia. We describe a patient with hypertrophic cardiomyopathy (HCM) who developed multiple, both focal and macroreentrant left ATs associated with a spontaneous scar located at the aorta-left atrium (LA) contiguous area. CASE PRESENTATION: A 65-year-old man with HCM complained of palpitations. Twelve-lead electrocardiogram showed narrow QRS tachycardia with 2:1 atrioventricular conduction. Two sessions of radiofrequency ablation (RFA) were required to eliminate all left ATs. In the first session, 3-dimensional electroanatomical mapping fused with the image constructed by multi-detector computed tomography showed a clockwise macroreentrant AT (AT1) associated with a low-voltage or dense scar area located along the aorta-LA contiguous area. AT1 was eliminated by RFA to the narrow isthmus with slow conduction velocity within the scar. Additional ATs (AT2-AT4) occurred 1 month after the first ablation. In the second session, AT2 and AT3 were identified as focal ATs with centrifugal propagation and few accompanying fragmentations, and AT4 as a macroreentrant AT with features similar to AT1. AT2 and AT3 were successfully eliminated by performing RFA to the earliest activation site, and AT4 was terminated by performing RFA to the narrow isthmus with slow conduction velocity. No ATs have recurred for 11 months after these RFAs. Interestingly, the substrate for all left ATs was associated with the aorta-LA contiguous area. CONCLUSION: To our knowledge, this is the first case of multiple, both focal and macroreentrant left ATs associated with a contiguous aorta-LA spontaneous scar area in a patient with HCM.

Double-device therapy in a patient with long QT syndrome.

A 26-year-old man with long QT syndrome (LQTS) underwent subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation. The patient exhibited sinus bradycardia relative to his age. The heart rate decreased, and the QT interval became longer with the administration of ß-blockers, the first-line therapy for LQTS. The patient experienced frequent S-ICD discharges. Subsequently, a single-chamber pacemaker was implanted, and the 12-lead electrocardiogram showed atrial pacing and ventricular sensing at 60 beats per minute with a shorter QTc interval. After converting to "double-device therapy," the patient did not experience any ventricular arrhythmia events.

Hybrid ablation for persistent atrial fibrillation: a narrative review.

Background and Objective: Treatment for atrial fibrillation (AF) has evolved significantly, with pulmonary vein isolation (PVI) becoming an established treatment. However, the outcomes following catheter ablation for persistent AF remain unsatisfactory. Hybrid catheter-surgical ablation has emerged as a therapeutic approach for persistent AF, combining the strengths of both interventions. The purpose of this narrative review is to comprehensively examine the current state of knowledge regarding hybrid ablation for AF. Methods: A thorough PubMed search using the terms "hybrid ablation", "atrial fibrillation", "catheter ablation", and "guideline on cardiology" within the timeframe of 1980 to 2024 resulted in 138,969 articles. Consensus on the selected articles was reached through a series of structured meetings and discussions. Key Content and Findings: PVI has demonstrated higher sinus rhythm maintenance rates, especially for paroxysmal AF. However, the efficacy is not as high for persistent AF. Additional ablation strategies, such as linear ablation, complex fractionated atrial electrogram ablation, low voltage zone ablation as well as posterior wall isolation, lack consistent evidence of effectiveness. Hybrid ablation, involving collaboration between cardiac surgeons and electrophysiologists, presents a promising alternative for hard-to-treat AF. Recent studies report favorable outcomes of hybrid ablation, with atrial arrhythmia-free rates ranging from 53.5% to 76%, surpassing those of catheter ablation alone, which might result from better lesion durability or intervention for non-PV foci and left atrial appendage excision or closure during hybrid ablation. The rate of complications associated with hybrid ablation is higher than catheter ablation alone. Conclusions: While favorable outcomes of hybrid ablation for persistent AF have been reported, it is not recommended for all AF patients due to its invasiveness compared to catheter ablation. Additionally, some patients with persistent AF maintain sinus rhythm with catheter ablation alone. More clinical data are needed to determine which patients are suitable candidates for hybrid ablation.

Impact of fracture-prone implantable cardioverter defibrillator leads on long-term patient mortality.

Background: The long-term relationship between fracture-prone implantable cardioverter-defibrillator (ICD) leads and poor prognosis remains unclear in Japanese patients. Methods: We conducted a retrospective review of the records of 445 patients who underwent implantation of advisory/Linox leads (Sprint Fidelis, 118; Riata, nine; Isoline, 10; Linox S/SD, 45) and non-advisory leads (Endotak Reliance, 33; Durata, 199; Sprint non-Fidelis, 31) between January 2005 and June 2012 at our hospital. The primary outcomes were all-cause mortality and ICD lead failure. The secondary outcomes were cardiovascular mortality, heart failure (HF) hospitalization, and the composite outcome of cardiovascular mortality and HF hospitalization. Results: During the follow-up period (median, 8.6 [4.1-12.0] years), there were 152 deaths: 61 (34%) in patients with advisory/Linox leads and 91 (35%) in those with non-advisory leads. There were 32 ICD lead failures: 27 (15%) in patients with advisory/Linox leads and five (2%) in those with non-advisory leads. Multivariate analysis for ICD lead failure demonstrated that the advisory/Linox leads had a 6.65-fold significantly greater risk of ICD lead failure than non-advisory leads. Congenital heart disease (hazard ratio 2.51; 95% confidence interval 1.08-5.83; p = .03) could also independently predict ICD lead failure. Multivariate analysis for all-cause mortality demonstrated no significant association between advisory/Linox leads and all-cause mortality. Conclusions: Patients who have implanted fracture-prone ICD leads should be carefully followed up for ICD lead failure. However, these patients have a long-term survival rate comparable with that of patients with non-advisory ICD leads in Japanese patients.