Significant Delayed Activation on the Right Ventricular Outflow Tract Represents Complete Right Bundle-Branch Block Pattern in Brugada Syndrome.

Background The appearance of complete right bundle-branch block (CRBBB) in Brugada syndrome (BrS) is associated with an increased risk of ventricular fibrillation. The pathophysiological mechanism of CRBBB in patients with BrS has not been well established. We aimed to clarify the significance of a conduction delay zone associated with arrhythmias on CRBBB using body surface mapping in patients with BrS. Methods and Results Body surface mapping was recorded in 11 patients with BrS and 8 control patients both with CRBBB. CRBBB in control patients was transiently exhibited by unintentional catheter manipulation (proximal RBBB). Ventricular activation time maps were constructed for both of the groups. We divided the anterior chest into 4 areas (inferolateral right ventricle [RV], RV outflow tract [RVOT], intraventricular septum, and left ventricle) and compared activation patterns between the 2 groups. Excitation propagated to the RV from the left ventricle through the intraventricular septum with activation delay in the entire RV in the control group (proximal RBBB pattern). In 7 patients with BrS, excitation propagated from the inferolateral RV to the RVOT with significant regional activation delay. The remaining 4 patients with BrS showed a proximal RBBB pattern with the RVOT activation delay. The ventricular activation time in the inferolateral RV was significantly shorter in patients with BrS without a proximal RBBB pattern than in control patients. Conclusions The CRBBB morphology in patients with BrS consisted of 2 mechanisms: (1) significantly delayed conduction in the RVOT and (2) proximal RBBB with RVOT conduction delay. Significant RVOT conduction delay without proximal RBBB resulted in CRBBB morphology in patients with BrS.

Usefulness of right ventriculography compared with computed tomography for ruling out the possibility of lead perforation before lead extraction.

PURPOSE: High-risk patients can be identified by preprocedural computed tomography (CT) before lead extraction. However, CT evaluation may be difficult especially for lead tip identification due to artifacts in the leads. Selective right ventriculography (RVG) may enable preprocedural evaluation of lead perforation. We investigated the efficacy of RVG for identifying right ventricular (RV) lead perforation compared with CT in patients who underwent lead extraction. METHODS: Ninety-five consecutive patients who were examined by thin-section non-ECG-gated multidetector CT and RVG before lead extraction were investigated retrospectively. Newly recognized pericardial effusion after lead extraction was used as a reference standard for lead perforation. We analyzed the prevalence of RV lead perforation diagnosed by each method. The difference in the detection rates of lead perforation by RVG and CT was evaluated. RESULTS: Of the 115 RV leads in the 95 patients, lead perforation was diagnosed for 35 leads using CT, but the leads for 29 (83%) of those 35 leads diagnosed as lead perforation by CT were shown to be within the right ventricle by RVG. Three patients with 5 leads could not be evaluated by CT due to motion artifacts. The diagnostic accuracies of RVG and CT were significantly different (p < 0.001). There was no complication of pericardial effusion caused by RV lead extraction. CONCLUSION: RVG for identification of RV lead perforation leads to fewer false-positives compared to non-ECG-gated CT. However, even in cases in which lead perforation is diagnosed, most leads may be safely extracted by transvenous lead extraction.

Significance of Exercise-Related Ventricular Arrhythmias in Patients With Brugada Syndrome.

Background Sinus tachycardia during exercise attenuates ST-segment elevation in patients with Brugada syndrome, whereas ST-segment augmentation after an exercise test is a high-risk sign. Some patients have premature ventricular contractions (PVCs) related to exercise, but the significance of exercise-related PVCs in patients with Brugada syndrome is still unknown. The objective of this study was to determine the significance of exercise-related PVCs for predicting occurrence of ventricular fibrillation (VF) in patients with Brugada syndrome. Methods and Results The subjects were 307 patients with Brugada syndrome who performed a treadmill exercise test. We evaluated the occurrence of PVCs at rest, during exercise and at the peak of exercise, and during recovery after exercise (0-5 minutes). We followed the patients for 92±68 months and evaluated the occurrence of VF. PVCs occurred in 82 patients (27%) at the time of treadmill exercise test: PVCs appeared at rest in 14 patients (4%), during exercise in 60 patients (20%), immediately after exercise (0-1.5 minutes) in 28 patients (9%), early after exercise (1.5-3 minutes) in 18 patients (6%), and late after exercise (3-5 minutes) in 12 patients (4%). Thirty patients experienced VF during follow-up. Multivariable analysis including symptoms, spontaneous type 1 ECG, and PVCs in the early recovery phase showed that these factors were independently associated with VF events during follow-up. Conclusions PVCs early after an exercise test are associated with future occurrence of VF events. Rebound of vagal nerve activity at the early recovery phase would promote ST-segment augmentation and PVCs in high-risk patients with Brugada syndrome.

Indication and prognostic significance of programmed ventricular stimulation in asymptomatic patients with Brugada syndrome.

AIMS: To establish the indication for programmed ventricular stimulation (PVS) for asymptomatic patients with Brugada syndrome (BrS), we evaluated the prognostic significance of PVS based on abnormal electrocardiogram (ECG) markers. METHODS AND RESULTS: One hundred and twenty-five asymptomatic patients with BrS were included. We performed PVS at two sites of the right ventricle with up to three extrastimuli [two pacing cycle lengths and minimum coupling interval (MCI) of 180 ms]. We followed the patients for 133 months and evaluated ventricular fibrillation (VF) events. Fragmented QRS (fQRS) and Tpeak-Tend (Tpe) interval were evaluated as ECG markers for identifying high-risk patients. Fragmented QRS and long Tpe interval (≥100 ms) were observed in 66 and 37 patients, respectively. Ventricular fibrillation was induced by PVS in 60 patients. During follow-up, 10 patients experienced VF events. Fragmented QRS, long Tpe interval, and PVS-induced VF with an MCI of 180 ms or up to two extrastimuli were associated with future VF events (fQRS: P = 0.015, Tpe ≥ 100 ms: P = 0.038, VF induction: P < 0.001). However, PVS-induced VF with an MCI of 200 ms was less specific (P = 0.049). The frequencies of ventricular tachyarrhythmia events during follow-up were 0%/year with no ECG markers and 0.1%/year with no VF induction. The existence of two ECG factors with induced VF was strongly associated with future VF events (event rate: 4.4%/year, P < 0.001), and the existence of one ECG factor with induced VF was also associated (event rate: 1.3%/year, P = 0.011). CONCLUSION: We propose PVS with a strict protocol for asymptomatic patients with fQRS and/or long Tpe interval to identify high-risk patients.

Prognosis after lead extraction in patients with cardiac implantable electronic devices infection: Comparison of lead-related infective endocarditis with pocket infection in a Japanese single-center experience.

BACKGROUND: The increase in the use of cardiac implantable electronic devices (CIEDs) has been associated with an increase in CIED-related infections. Transvenous lead extraction is safe and effective for patients with CIED-related infections; however, the mortality rate in these patients is high. The prognosis after transvenous lead extraction in Japanese patients, especially those with lead-related infective endocarditis, has not been evaluated. Then, the purpose of this study is to clarify the prognosis after transvenous lead extraction in Japanese patients with CIED-related infections at a single Japanese center. METHODS: A total of 107 patients who underwent transvenous lead extraction were retrospectively reviewed. The patients were divided into a lead-related infective endocarditis group (n = 32) and a pocket infection group (n = 75). Procedure success rate and prognosis after lead extraction were evaluated between the two groups. RESULTS: Procedure success rate was not significantly different between the groups. There were no deaths associated with the procedure or with infection. The survival rate was not significantly different at 1 year or at a median of 816 days (lead-related infective endocarditis vs pocket infection; 93.7% vs 94.7%, P = 1.000; 78.1% vs 81.3%, P = 0.791) Time to reimplantation and duration of hospital stay and antibiotics therapy were significantly longer for patients with lead-related infective endocarditis. CONCLUSION: In this study, the prognosis for patients with lead-related infective endocarditis after transvenous lead extraction was favorable. Thus, extraction should be strongly recommended, even if the general condition of the patient is poor.

A Low Critical Event Rate Despite a High Abnormal Event Rate in Patients with Cardiac Implantable Electric Devices Followed Up by Remote Monitoring.

Objective Remote monitoring (RM) of cardiac implantable electric devices (CIEDs) has been advocated as a healthcare standard. However, expert consensus statements suggest that all patients require annual face-to-face follow-up consultations at outpatient clinics even if RM reveals no episodes. The objective of this study was to determine the critical event rate after CIED implantation through RM. Methods This multicenter, retrospective, cohort study evaluated patients with pacemakers (PMs), implantable cardioverter defibrillators (ICDs), or cardiac resynchronization therapy defibrillator (CRT-Ds) and analyzed whether or not the data drawn from RM included abnormal or critical events. Patients A total of 1,849 CIED patients in 12 hospitals who were followed up by the RM center in Okayama University Hospital were included in this study. Results During the mean follow-up period of 774.9 days, 16,560 transmissions were analyzed, of which 11,040 (66.7%) were abnormal events and only 676 (4.1%) were critical events. The critical event rate in the PM group was significantly lower than that in the ICD or CRT-D groups (0.9% vs. 5.0% or 5.9%, p<0.001). A multivariate analysis revealed that ICD, CRT-D, and a low ejection fraction were independently associated with critical events. In patients with ICD, the independent risk factors for a critical event were old age, low ejection fraction, Brugada syndrome, dilated phase hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy. Conclusion Although abnormal events were observed in two-thirds of the transmitted RM data, the critical event rate was <1% in patients with a PM, which was lower in comparison to the rates in patients with ICDs or CRT-Ds. A low ejection fraction was an independent predictor of critical events.

Radiofrequency catheter ablation prior to percutaneous coronary intervention in patients with atrial fibrillation coexisting with stable coronary artery disease: a single-center pilot study.

Atrial fibrillation (AF) frequently coexists with cardiovascular disease (CAD) in a clinical setting. However, the optimum therapy for AF patients who have concomitant CAD is unclear. We retrospectively examined the efficacy and safety of radiofrequency catheter ablation (RFCA) prior to percutaneous coronary intervention (PCI) in patients with AF who had concomitant stable CAD. Between January 2014 and December 2015, a total 264 patients (179 men; mean age, 65.5 ± 10.1 years) who were referred to undergo a first RFCA procedure were reviewed in this study. Of the 264 patients, 41 (15.5%) had stable CAD detected by multi-detector computed tomography before RFCA. Thirty-seven patients who had AF with stable CAD were divided into two treatment arms: (1) RFCA prior to PCI (n = 13) and (2) PCI prior to RFCA (n = 24) [four patients excluded because of left main coronary artery disease (LMCA) or triple vessel disease (TVD)]. The median follow-up was 14 (IQR 8-19) months. There was no significant difference in AF recurrence rate after the procedure between the RFCA first group and PCI first group (P = 0.515). No symptomatic cardiovascular events occurred the during follow-up period. The PCI first group had a significantly longer duration of triple therapy (188.5 ± 167 days vs 5.6 ± 24.5 days, P = 0.01) and all of the four bleeding events occurred during triple therapy (P = 0.01). The results of this single-center pilot study suggested that prior RFCA in patients with AF coexisting with CAD could have fewer serious bleeding events than prior PCI.

Progression of electrocardiographic abnormalities associated with initial ventricular fibrillation in asymptomatic patients with Brugada syndrome.

BACKGROUND: Various risk stratifications in asymptomatic patients with Brugada syndrome (BrS) have been proposed, but the electrophysiological change that promotes ventricular fibrillation (VF) is still unknown. OBJECTIVE: The aim of this study was to clarify the changes in electrocardiographic (ECG) markers at the onset of VF from ECGs recorded when patients were still asymptomatic. METHODS: The subjects of this study included 14 patients with VF and 48 consecutive asymptomatic patients with BrS. We compared ECGs before the initial VF events (>6 months; early phase) with ECGs at the initial VF events (late phase). In asymptomatic patients, we evaluated ECGs at 2 time points with an interval of >6 months. We evaluated various ECG markers including type 1 ECG and fragmented QRS (fQRS; multiple spikes within the QRS complex). RESULTS: ECG parameters of the early and late phases were not different except for decreased ST voltage and low incidence of type 1 ECG in asymptomatic patients. There were no differences in ECG parameters of the early phase between patients with VF and asymptomatic patients. In patients with VF, ECGs at the late phase had longer QRS intervals and intervals between the peak and the end of the T wave and more frequent type 1 ECG and fQRS than did ECGs at the early phase. Those changes were associated with initial VF events (QRS widening: odds ratio [OR] 11.5, P < .01; interval between the peak and the end of the T wave: OR 11.6, P < .01; fQRS: odds ratio 15.3, P < .01; type 1 ECG: OR 6.6, P < .05). CONCLUSION: QRS and ST-T wave abnormalities developed in association with the initial VF events. Aggravation of the conduction disturbance in addition to BrS-ECG promotes VF.

Shanghai Score System for Diagnosis of Brugada Syndrome: Validation of the Score System and System and Reclassification of the Patients.

OBJECTIVES: The principal objective was to perform an initial test of the Shanghai Brugada Scoring System. Diagnosis of probable and/or definite Brugada syndrome (BrS), possible BrS, and nondiagnostic outcomes were assigned scores of ≥3.5, 2 to 3, and <2 points, respectively. The proposed score system was based on the available published reports and on weighted coefficients derived from limited datasets, with the understanding that these recommendations would need to undergo continuing validation. BACKGROUND: The 2016 HRS/EHRA/APHRS/SOLAECE J-Wave Syndrome Consensus Report proposed a scoring system for diagnosis of BrS that takes into account electrocardiographic recordings, genetic results, clinical characteristics, and family history. METHODS: The patient population consisted of 393 patients evaluated at our hospital for BrS (271 asymptomatic, 99 with syncope, and 23 with ventricular fibrillation [VF]) between 1996 and 2016. Subjects were classified into 4 groups: group A with a score of ≤3.0 points (n = 45); group B with a score of 3.5 points (n = 186); group C with a score of 4.0 to 5.0 points (n = 81); and group D with a score of ≥5.5 points (n = 81). RESULTS: A total of 348 (88%) patients had probable and/or definite BrS, and 81 (20%) had a score ≥5.5. During a follow-up of 97.3 months (range: 39.7 to 142.1 months), 43 patients experienced VF. Significant differences were seen among the 4 groups (p = 0.01). A malignant arrhythmic event did not occur in any patient with possible or nondiagnostic BrS. CONCLUSIONS: This study provided validation for the use of the Shanghai Score System for the diagnosis and risk stratification of patients with BrS.

Prognostic Significance of the Sodium Channel Blocker Test in Patients With Brugada Syndrome.

BACKGROUND: A drug provocation test using a sodium channel blocker (SCB) can unmask a type 1 ECG pattern in patients with Brugada syndrome. However, the prognostic value of the results of an SCB challenge is limited in patients with non-type 1 ECG. We investigated the associations of future risk for ventricular fibrillation with SCB-induced ECG changes and ventricular tachyarrhythmias (VTAs). METHODS AND RESULTS: We administered intravenous pilsicainide to 245 consecutive patients with Brugada syndrome (181 patients with spontaneous type 1 ECG, 64 patients with non-type 1 ECG). ECG parameters before and after the test and occurrence of drug-induced VTAs were evaluated. During a mean follow-up period of 113±57 months, fatal VTA events occurred in 31 patients (sudden death: n=3, ventricular tachycardia/ventricular fibrillation: n=28). Symptomatic patients and spontaneous type 1 ECG were associated with future fatal arrhythmic events. Univariable analysis of ECG parameters after the test showed that long PQ and QRS intervals, high ST level, and SCB-induced VTAs were associated with later VTA events during follow-up. Multivariable analysis showed that symptomatic patients, high ST level (V1) ≥0.3 mV after the test, and SCB-induced VTAs were independent predictors for future fatal arrhythmic events (hazard ratios: 3.28, 2.80, and 3.62, 95% confidence intervals: 1.54-7.47, 1.32-6.35, and 1.64-7.75, respectively; P<0.05). CONCLUSIONS: SCB-induced VTAs and ST-segment augmentation are associated with an increased risk of the development of ventricular tachycardia/ventricular fibrillation events during follow-up in patients with Brugada syndrome.

Identification of electrocardiographic risk markers for the initial and recurrent episodes of ventricular fibrillation in patients with Brugada syndrome.

INTRODUCTION: New onset of ventricular fibrillation (VF) in asymptomatic patients with Brugada-type ECG is not frequent, but it cannot be negligible. Risk markers for predicting VF are usually based on results of analysis in symptomatic patients, and they have not been determined for asymptomatic patients. We analyzed ECG markers in patients with Brugada syndrome to differentiate the risk factors for VF in both symptomatic and asymptomatic patients. METHODS: The subjects were 471 patients with Brugada syndrome and we divided the subjects into two groups: Asymptomatic group (n = 326) and Symptomatic group (syncope: n = 122, VF: n = 23). We analyzed the following ECG markers: RR, PQ, QRS, QT and Tpeak-Tend (Tpe) intervals, ST level, atrial fibrillation (AF), atrioventricular block, spontaneous type 1 ECG, early repolarization (ER) and fragmented QRS (fQRS). RESULTS: During follow-up (91 ± 64 months), 41 patients experienced VF (Asymptomatic: n = 10, Symptomatic: n = 31). Univariable analysis showed that spontaneous type 1 ECG, Tpe interval (≥95 milliseconds), high ST level (≥0.52 mV) and fQRS were common predictors for VF in both the Asymptomatic and Symptomatic groups. In addition to the common risk factors, wide QRS (≥107 milliseconds), long QT interval (≥420 milliseconds), ER and AF were predictors for VF in Symptomatic group. Multivariable analysis of the Symptomatic group showed fQRS, Tpe and ER were independent predictors of prognosis. CONCLUSIONS: fQRS and Tpe interval are common risk factors for VF in both asymptomatic and symptomatic patients, whereas ER is a predictor for recurrent VF.

Analysis of arrhythmic events is useful to detect lead failure earlier in patients followed by remote monitoring.

BACKGROUND: Remote monitoring (RM) has been advocated as the new standard of care for patients with cardiovascular implantable electronic devices (CIEDs). RM has allowed the early detection of adverse clinical events, such as arrhythmia, lead failure, and battery depletion. However, lead failure was often identified only by arrhythmic events, but not impedance abnormalities. OBJECTIVE: To compare the usefulness of arrhythmic events with conventional impedance abnormalities for identifying lead failure in CIED patients followed by RM. METHODS: CIED patients in 12 hospitals have been followed by the RM center in Okayama University Hospital. All transmitted data have been analyzed and summarized. RESULTS: From April 2009 to March 2016, 1,873 patients have been followed by the RM center. During the mean follow-up period of 775 days, 42 lead failure events (atrial lead 22, right ventricular pacemaker lead 5, implantable cardioverter defibrillator [ICD] lead 15) were detected. The proportion of lead failures detected only by arrhythmic events, which were not detected by conventional impedance abnormalities, was significantly higher than that detected by impedance abnormalities (arrhythmic event 76.2%, 95% CI: 60.5-87.9%; impedance abnormalities 23.8%, 95% CI: 12.1-39.5%). Twenty-seven events (64.7%) were detected without any alert. Of 15 patients with ICD lead failure, none has experienced inappropriate therapy. CONCLUSIONS: RM can detect lead failure earlier, before clinical adverse events. However, CIEDs often diagnose lead failure as just arrhythmic events without any warning. Thus, to detect lead failure earlier, careful human analysis of arrhythmic events is useful.

Initial experience with the subcutaneous implantable cardioverter-defibrillator in a single Japanese center.

BACKGROUND: The subcutaneous implantable cardioverter-defibrillator (S-ICD) is recognized as a viable alternative to the transvenous ICD. The safety and efficacy of this device has been demonstrated in Western countries, but studies with S-ICD implantation in Japanese patients have not been reported. METHODS AND RESULTS: Twelve patients received an S-ICD implant in our institute between February and September 2016. All S-ICDs were successfully implanted without complications. One appropriate and one inappropriate therapy was identified. CONCLUSIONS: S-ICD implantation appears to provide a viable alternative to transvenous ICD implantation for some Japanese patients. However, we should perform careful follow-up of patients to eliminate inappropriate therapy.

Comparison of longevity and clinical outcomes of implantable cardioverter-defibrillator leads among manufacturers.

BACKGROUND: An early failure of the Biotronik Linox S/SD implantable cardioverter-defibrillator (ICD) lead has been reported. We have also experienced several cases with early failure of Linox leads. OBJECTIVE: Our aim was to assess the longevity of Linox S/SD (Biotronik, Berlin, Germany) compared with Sprint Fidelis (Medtronic, Minneapolis, MN), Sprint Quattro (Medtronic), and Endotak Reliance (Boston Scientific, Natick, Massachusetts) leads. METHODS: We retrospectively reviewed patients who had undergone implantation of Linox S/SD (n = 90), Sprint Fidelis (n = 37), Sprint Quattro (n = 27), or Endotak Reliance (n = 50) leads between June 2000 and December 2013 at our hospital. Variables associated with lead failure were assessed by the Kaplan-Meier method and Cox survival modeling. RESULTS: Failure rates of Linox, Sprint Fidelis, and Endotak leads were 3.2%/year (7-year survival rate, 81.0%), 3.4%/year (7-year survival rate, 77.2%), and 0.61%/year (7-year survival rate, 95.8%), respectively. No lead failure was found with Sprint Quattro leads. The survival probability of Linox leads was significantly lower than that of Endotak leads (P = .049) and comparable to that of Sprint Fidelis leads (P = .69). In univariate analysis, age was the only predictor of Linox lead failure. Patients <58 years old were at significantly increased risk of lead failure compared with patients ≥58 years old (hazard ratio, 9.0; 95% confidence interval, 1.13-71.3; P = .037). CONCLUSION: In our single-center experience, the survival rate of Linox leads was unacceptably low. The only predictor of Linox lead failure was age at implantation. This is the first description of a lower survival rate for Linox leads in an Asian population.

Distribution and Prognostic Significance of Fragmented QRS in Patients With Brugada Syndrome.

BACKGROUND: Fragmented QRS complexes (fQRS) in the right precordial leads are associated with occurrence of ventricular fibrillation (VF) in Brugada syndrome. Recently, epicardial mapping has revealed abnormal electrograms at the right ventricular (RV) outflow tract and inferior region of the right ventricle. fQRS may reflect the extent of the area of abnormal potentials, but whether the distribution of fQRS has prognostic value is not known. METHODS AND RESULTS: We evaluated the existence of fQRS in 456 patients with Brugada syndrome, including 117 patients with syncope and 23 patients with VF. The region of fQRS was defined as inferior (II, III, and aVF), lateral (I, aVL, and V5 and V6), anterior (V3 and V4), RV (V1 and V2), and RV outflow tract (V1 and V2 at the third intercostal space). fQRS were present in 229 patients (RV outflow tract in 175, inferior in 135, RV in 90, and lateral in 16 patients). During follow-up (mean 91 months), 39 patients experienced VF. In univariable analyses, fQRS in any distribution and fQRS in each region excluding the RV were associated with VF. Multivariable analysis showed that fQRS in the inferior (hazard ratio, 3.9; confidence interval, 1.9-8.5), lateral (hazard ratio, 3.5; confidence interval, 1.2-8.2), and RV outflow tract (hazard ratio, 2.5; confidence interval, 1.2-5.6) were associated with VF events. The presence of multiple regions of fQRS was associated with worse prognosis. CONCLUSIONS: The distribution of fQRS is associated with prognosis in Brugada syndrome, further supporting the association of fQRS and arrhythmia substrate.

Complete right bundle branch block and QRS-T discordance can be the initial clue to detect S-ICD ineligibility.

BACKGROUND: In order to minimize inappropriate shocks of subcutaneous implantable cardioverter-defibrillators (S-ICD), it is important to recognize who is suitable for S-ICD indication. This study aimed to clarify what types of cardiac disease are likely to fulfill the S-ICD screening criteria and ineligible factors for S-ICD in the standard 12-lead electrocardiogram (ECG). METHODS: A total of 348 patients with heart disease were enrolled. They were assessed by supine and standing ECG recording to simulate the 3 S-ICD sensing vectors and standard 12-lead ECG, simultaneously. Clinical and ECG characteristics were analyzed to compare the patients who are eligible and ineligible with S-ICD screening ECG indication. RESULTS: The mean age of study patients was 49±21 years and 244 (70%) were men. Nineteen percent of patients were unsuitable for S-ICD. There was no significant difference in ineligibility for S-ICD among cardiac diseases (p=0.48). Univariate analysis showed complete right bundle branch block (CRBBB), QRS-T discordance in lead II, and QRS-T discordance in 3 leads (I, II, and aVF) were more frequent in patients who were ineligible for S-ICD than in the eligible group. Multivariate regression analysis showed CRBBB and QRS-T discordance in 3 leads were independent predictors for ineligibility of S-ICD. CONCLUSION: There are no differences in eligibility of S-ICD among types of cardiac diseases. CRBBB and QRS-T discordance were independent predictors for ineligibility.