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Background: Left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP) are referred to as left bundle branch area pacing., Objective: This study investigated whether long-term clinical outcomes differ in patients undergoing LBBP, LVSP, and biventricular pacing (BiVP) for cardiac resynchronization therapy (CRT)., Methods: Consecutive patients with reduced left ventricular ejection fraction (LVEF <50%) undergoing CRT were prospectively enrolled if they underwent successful LBBP, LVSP, or BiVP. The primary composite end point was all-cause mortality or heart failure hospitalization. Secondary end points included all-cause mortality, heart failure hospitalization, and echocardiographic measures of reverse remodeling., Results: A total of 259 patients (68 LBBP, 38 LVSP, and 153 BiVP) were observed for a mean duration of 28.8 ± 15.8 months. LBBP was associated with a significantly reduced risk of the primary end point by 78% compared with both BiVP (7.4% vs 41.2%; adjusted hazard ratio [aHR], 0.22 [0.08-0.57]; P = .002) and LVSP (7.4% vs 47.4%; aHR, 0.22 [0.08-0.63]; P = .004]. The adjusted risk of all-cause mortality was significantly higher in LVSP than in BiVP (31.6% vs 7.2%; aHR, 3.19 [1.38-7.39]; P = .007) but comparable between LBBP and BiVP (2.9% vs 7.2%; aHR, 0.33 [0.07-1.52], P = .155). Propensity score adjustment also obtained similar results. LBBP showed a higher rate of echocardiographic response (ΔLVEF ≥10%: 60.0% vs 36.2% vs 16.1%; P < .001) than BiVP or LVSP., Conclusion: LBBP yielded long-term clinical outcomes superior to those of BiVP and LVSP. The role of LVSP for CRT needs to be reevaluated because of its high mortality risk., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Left bundle branch pacing (LBBP) achieves resynchrony and improves cardiac function in heart failure (HF) patients with reduced ejection fraction (EF) by correcting left bundle branch block (LBBB). Few data on the efficacy of early LBBP in HF with mildly reduced EF (HFmrEF) and LBBB have been reported., Objective: The purpose of this study was to explore the efficacy of early LBBP in patients with HFmrEF and LBBB., Methods: Consecutive patients with HFmrEF (left ventricular EF [LVEF] 35%-50%) and LBBB were prospectively enrolled to receive LBBP (Early-LBBP group) plus guideline-directed medical therapy (GDMT) or GDMT alone (GDMT group). Study outcomes included changes in LVEF, LV end-diastolic diameter (LVEDD), New York Heart Association (NYHA) functional classification, and N-terminal pro-brain natriuretic peptide (NT-proBNP), and clinical events (HF rehospitalization or syncope). Subgroup analysis compared efficacy of LBBP between patients with LBBB only without comorbidities or late gadolinium enhancement (LGE) (LBBB-Only group) and patients with either comorbidities or LGE (LBBB-Combined group)., Results: Fifty-four patients were enrolled and analyzed (37 Early-LBBP group; 15 GDMT group). LBBP achieved greater improvement in LVEF (+14.75% ± 7.37% vs -2.42% ± 2.84%; P <.001), reduction of LVEDD (-7.51 ± 5.40 mm vs -0.87 ± 4.36 mm; P <.001) and NYHA classification (-0.84 ± 0.76 vs -0.13 ± 0.74; P = .004), and similar reduction of NT-proBNP (-408.83 ± 920.29 pg/mL vs -229.05 ± 1579.17 pg/mL; P = .610) at 6 months. Early LBBP showed significantly reduced clinical events (0.0% vs 40.0%; P <.001) after 20.68 ± 13.55 months of follow-up. Subgroup analysis showed patients in the LBBB-Only group benefited more from LBBP with regard to LVEF improvement and LVEDD reduction than the LBBB-Combined group., Conclusion: Early LBBP with GDMT demonstrated greater improvement of cardiac function and reduced clinical events than GDMT alone in patients with HFmrEF and LBBB., (Copyright © 2023 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Studies have shown that the conventional parameters characterizing left ventricular mechanical dyssynchrony (LVMD) measured on gated SPECT myocardial perfusion imaging (MPI) have their own statistical limitations in predicting cardiac resynchronization therapy (CRT) response. The purpose of this study is to discover new predictors from the polarmaps of LVMD by deep learning to help select heart failure patients with a high likelihood of response to CRT., Methods: One hundred and fifty-seven patients who underwent rest gated SPECT MPI were enrolled in this study. CRT response was defined as an increase in left ventricular ejection fraction (LVEF) > 5% at 6 [Formula: see text] 1 month follow up. The autoencoder (AE) technique, an unsupervised deep learning method, was applied to the polarmaps of LVMD to extract new predictors characterizing LVMD. Pearson correlation analysis was used to explain the relationships between new predictors and existing clinical parameters. Patients from the IAEA VISION-CRT trial were used for an external validation. Heatmaps were used to interpret the AE-extracted feature., Results: Complete data were obtained in 130 patients, and 68.5% of them were classified as CRT responders. After variable selection by feature importance ranking and correlation analysis, one AE-extracted LVMD predictor was included in the statistical analysis. This new AE-extracted LVMD predictor showed statistical significance in the univariate (OR 2.00, P = .026) and multivariate (OR 1.11, P = .021) analyses, respectively. Moreover, the new AE-extracted LVMD predictor not only had incremental value over PBW and significant clinical variables, including QRS duration and left ventricular end-systolic volume (AUC 0.74 vs 0.72, LH 7.33, P = .007), but also showed encouraging predictive value in the 165 patients from the IAEA VISION-CRT trial (P < .1). The heatmaps for calculation of the AE-extracted predictor showed higher weights on the anterior, lateral, and inferior myocardial walls, which are recommended as LV pacing sites in clinical practice., Conclusions: AE techniques have significant value in the discovery of new clinical predictors. The new AE-extracted LVMD predictor extracted from the baseline gated SPECT MPI has the potential to improve the prediction of CRT response., (© 2022. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.)

Background: Left bundle branch pacing (LBBP) is an emerging physiological pacing modality. How to differentiate LBBP from left ventricular septal pacing (LVSP) remains challenging., Objective: We aimed to develop a new personalized intraoperative criterion to confirm left bundle branch (LBB) capture in patients with or without heart failure (HF)., Methods: Patients were enrolled if 12-lead surface electrocardiograms of LBBP, LVSP, temporary His bundle pacing (HBP), and right ventricular septal pacing (RVSP) were recorded during the procedure, with the leads placed in the basal midseptal region. Left ventricular activation time (LVAT) was measured during different pacing modalities. ΔLVAT1 was defined as the difference in LVAT between HBP and LBBP/LVSP. ΔLVAT2 was estimated by the difference in LVAT between RVSP and LBBP/LVSP. ΔLVAT1% and ΔLVAT2% were calculated as the percent reduction of ΔLVAT1 and ΔLVAT2, respectively., Results: A total of 105 consecutive patients were included, of whom 80 (76.2%) had normal cardiac function (65 LBBP and 15 LVSP) and 25 had HF. Patients with LBBP showed significantly shorter LVAT than did those with LVSP. In patients with normal cardiac function, a cutoff value of ΔLVAT1 > 12.5 ms showed 73.9% sensitivity and 93.3% specificity to confirm LBB capture. In patients with HF, a cutoff value of ΔLVAT1% > 9.8% exhibited great accuracy for LBB capture (sensitivity 92.0%; specificity 92.3%). The optimal value of ΔLVAT2% for differentiating LBBP from LVSP was 21.2%., Conclusion: Temporary HBP and RVSP can serve as references to confirm LBB capture in an individualized fashion in patients with or without HF., (Copyright © 2022 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Left bundle branch pacing (LBBP) is the most rapidly growing conduction system pacing technique that is capable of correcting intrinsic left bundle branch block (LBBB). As such, it is potentially an optimal alternative to cardiac resynchronization therapy (CRT) with biventricular pacing (BiVP)., Objectives: The authors sought to compare the efficacy of LBBP-CRT with BiVP-CRT in patients with heart failure and reduced left ventricular ejection fraction (LVEF)., Methods: This is a prospective, randomized trial of patients with nonischemic cardiomyopathy and LBBB with 6-month preplanned follow-up. Crossovers were allowed if LBBP or BiVP were unsuccessful. The primary endpoint was the difference in LVEF improvement between 2 groups. The secondary endpoints included changes in echocardiographic measurements, N-terminal pro-B-type natriuretic peptide (NT-proBNP), New York Heart Association functional class, 6-minute walk distance, QRS duration, and CRT response., Results: The study included 40 consecutive patients (20 males, mean age 63.7 years, LVEF 29.7% ± 5.6%). Crossovers occurred in 10% of LBBP-CRT and 20% of BiVP-CRT. All patients completed follow-up. Intention-to-treat analysis showed significantly higher LVEF improvement at 6 months after LBBP-CRT than BiVP-CRT (mean difference: 5.6%; 95% CI: 0.3-10.9; P = 0.039). LBBP-CRT also appeared to have greater reductions in left ventricular end-systolic volume (-24.97 mL; 95% CI: -49.58 to -0.36 mL) and NT-proBNP (-1,071.80 pg/mL; 95% CI: -2,099.40 to -44.20 pg/mL), and comparable changes in New York Heart Association functional class, 6-minute walk distance, QRS duration, and rates of CRT response compared with BiVP-CRT., Conclusions: LBBP-CRT demonstrated greater LVEF improvement than BiVP-CRT in heart failure patients with nonischemic cardiomyopathy and LBBB. (Left Bundle Branch Pacing Versus Biventricular Pacing for Cardiac Resynchronization Therapy [LBBP-RESYNC]; NCT04110431)., Competing Interests: Funding Support and Author Disclosures This work was supported by the National Natural Science Foundation of China (82070521, 81970284), Clinical Competence Improvement Project of Jiangsu Province Hospital (JSPH-MA-2020-3), Project on New Technology of Jiangsu Province (JX233C202103), and Chinese Academy of Medical Sciences Innovation Found for Medical Sciences (2020-I2M-C&T-B-007). Dr Ellenbogen has been a consultant for and has received honoraria and research support from Medtronic, Boston Scientific, Abbott, and Biotronik. Dr Gold has been a consultant for Medtronic, Boston Scientific, and EBR; has received research support from Medtronic, Boston Scientific, and Abbott; and has received honoraria from Medtronic and Boston Scientific. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2022 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Electrical reverse remodeling of native conduction is associated with better clinical outcome following cardiac resynchronization therapy (CRT). We aimed to describe characteristics, time course and long-term outcome of patients with complete electrical reverse remodeling (CERR) after resynchronization therapies., Methods: CRT candidates were treated with bi-ventricular, His bundle or left bundle branch pacing. CERR was defined if native QRS duration post-implantation was narrowed to ≤120 ms., Results: A total of 322 patients met the inclusion criteria. Among them, 66 were super-responders and 12 exhibited CERR. All 12 patients were diagnosed of non-ischemic cardiomyopathy with left bundle branch block (LBBB) meeting the Strauss criteria. The mean native QRS duration when CERR was achieved was 110.8 ± 10.0 ms, significantly shorter than the baseline (175.0 ± 18.8 ms). The occurrence of CERR varied from several days post-implantation to 18-month follow-up. The persistence of CERR also showed great variations. Eleven patients (91.7%, 11/12) showed echocardiographic super-response. Patients with CERR showed similar baseline characteristics compared to those with echocardiographic super-response but without CERR. Two patients with CERR showed different responses after bi-ventricular pacing was turned off. One patient remained stable with narrow QRS complex and great response. The other patient had reappearance of LBBB and decreased cardiac function, but recovered by turning on the device again., Conclusions: Patients with CERR exhibited great response to different resynchronization therapies. The time course of CERR and echocardiographic super-response varied greatly. The variability of native conduction system and accompanied changes of mechanical remodeling suggest the mechanisms of electrical-disorder related cardiomyopathy., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Background: Several studies have illustrated the use of echocardiography, magnetic resonance imaging, and nuclear imaging to optimize left ventricular (LV) lead placement to enhance the response of cardiac resynchronization therapy (CRT) in heart failure patients. We aimed to conduct a meta-analysis to determine the incremental efficacy of image-guided CRT over standard CRT., Methods: We searched PubMed, Cochrane library, and EMBASE to identify relevant studies. The outcome measures of cardiac function and clinical outcomes were CRT response, concordance of the LV lead to the latest sites of contraction (concordance of LV), heart failure (HF) hospitalization, mortality rates, changes of left ventricular ejection fraction (LVEF), and left ventricular end-systolic volume (LVESV)., Results: The study population comprised 1075 patients from eight studies. 544 patients underwent image-guided CRT implantation and 531 underwent routine implantation without imaging guidance. The image-guided group had a significantly higher CRT response and more on-target LV lead placement than the control group (RR, 1.33 [95% CI, 1.21 to 1.47]; p < 0.01 and RR, 1.39 [95% CI, 1.01 to 1.92]; p < 0.05, respectively). The reduction of LVESV in the image-guided group was significantly greater than that in the control group (weighted mean difference, - 12.46 [95% CI, - 18.89 to - 6.03]; p < 0.01). The improvement in LVEF was significantly higher in the image-guided group (weighted mean difference, 3.25 [95% CI, 1.80 to 4.70]; p < 0.01). Pooled data demonstrated no significant difference in HF hospitalization and mortality rates between two groups (RR, 0.89 [95% CI, 0.16 to 5.08]; p = 0.90, RR, 0.69 [95% CI, 0.37 to 1.29]; p = 0.24, respectively)., Conclusions: This meta-analysis indicates that image-guided CRT is correlated with improved CRT volumetric response and cardiac function in heart failure patients but not with lower hospitalization or mortality rate.

Background: Chronic right ventricular (RV) pacing is associated with an increased incidence of heart failure and mortality. Left bundle branch (LBB) pacing could produce near-physiological electrical activation and mechanical synchrony. We aimed to report the effects of upgrading to LBB pacing in heart failure patients after chronic RV pacing., Methods: The indications included pacing-induced cardiomyopathy (PICM) in Group 1 and heart failure after RV pacing with left ventricular ejection fraction (LVEF) ≥ 50% in Group 2. LBB pacing was achieved by penetrating the pacing lead to the subendocardium of left-sided interventricular septum through the venous access. Left ventricular activation time (LVAT) was measured from the pacing stimulus to the ascending peak of lead V5 or V6. All patients underwent clinical and echocardiographic evaluations before and after upgrading., Results: Totally 27 patients (13 in Group 1 and 14 in Group 2) were consecutively enrolled. The mean follow-up time after upgrade was 10.4 ± 6.1 months. Paced QRS duration was significantly shortened from 174.1 ± 15.8 milliseconds to 116.6 ± 11.7 milliseconds (p < .0001). The mean LVAT was 83.2 ± 11.7 milliseconds. LVEF increased from 40.3 ± 5.2% before upgrading to 48.1 ± 9.5% at follow-up in patients with PICM. Serum N-terminal probrain natriuretic peptide levels decreased and New York Heart Association classification improved in both groups. No upgrade-related complications were observed., Conclusions: Upgrading to LBB pacing was feasible and effective with improved cardiac function in heart failure patients with both reduced and preserved LVEF after RV pacing., (© 2020 Wiley Periodicals LLC.)

Background: Left bundle branch area pacing (LBBAP) was reported to improve cardiac function by correcting complete left bundle branch block (CLBBB). Our study aimed to compare the efficacy of LBBAP and biventricular pacing (BIVP) in heart failure patients with CLBBB., Methods: Ten patients prospectively underwent LBBAP (LBB-CRT group) and 30 patients received BIVP (BIV-CRT group) were matched using propensity score matching. LBBAP was achieved by the trans-interventricular septum method. Echocardiography, electrocardiogram, NYHA classification, and blood B-type natriuretic peptide concentration were evaluated at preimplantation and at 6-month follow up. CRT response was defined as at least 15% decrease in left ventricular end-systolic volume., Results: In the LBB-CRT group, CLBBB were successfully corrected by LBBAP with no complications. QRS duration (QRSd) significantly decreased after implantation in both groups, and the decrease of QRSd in the LBB-CRT group was significantly greater than that in the BIV-CRT group (60.80 ± 20.09 vs. 33.00 ± 21.48 ms, p = .0009). The echocardiographic measurements including left ventricular end-diastolic diameter, left ventricular end-systolic diameter, and left ventricular ejection fraction significantly improved after 6 months in both groups. The response rate was significantly higher in LBB-CRT group than BIV-CRT group (100.00% vs. 63.33%, p = .038). The percentage of patients in New York Heart Association classification Grades I and II was significantly higher in the LBB-CRT group compared with that in the BIV-CRT group (median 1.5 vs. 2.0, p = .029) at 6-month follow-up., Conclusions: It is effective and safe to correct CLBBB with LBBAP in heart failure patients. Compared with BIVP, LBBAP can better optimize electrical synchrony and improve cardiac function., (© 2020 Wiley Periodicals LLC.)

Objectives: To evaluate the response to cardiac resynchronization therapy (CRT) and the correlation between CRT and pulmonary artery hemodynamic parameters., Methods: The patients with chronic heart failure indicator for CRT were enrolled. The left ventricular end-systolic volume (LVESV) was measured by echocardiography and New York Heart Association (NYHA) classification was evaluated between one week before and six months after CRT. Mean pulmonary artery pressure (mPAP), pulmonary artery systolic pressure (PASP) and pulmonary vascular resistance (PVR) were measured by right heart catheterization. Left ventricular reverse remodeling (LVRR) is defined as a decrease of 15% or more in LVESV at the 6th month after CRT; Clinical response is defined as a decrease of NYHA classification at or above grade 1 at the 6th month after CRT. Pulmonary hypertension (PH) was defined as mPAP≥25 mmHg. According to the response, patients were divided into 3 groups: group A (LVRR+clinical response), group B (no LVRR+clinical response) and group C (no LVRR+no clinical response). The changes of NYHA classification, echocardiographic and pulmonary hemodynamic parameters were observed in the 3 groups. The Kaplan-Meier survival curve was used to analyze the differences in all-cause mortality, combined end-point events of death or re-hospitalization due to heart failure among different groups., Results: A total of 45 patients with CRT implantation [aged (63.27±9.55) years, 36 males] were included. The average follow-up period was (33.76±11.50) months. Thirty-one patients (68.89%) were in group A, 9 of whom with PH. Eight patients (17.78%) were in group B, 7 of whom with PH. Six patients were in group C, all with PH. Cardiac function including NYHA classification, echocardiographic and pulmonary hemodynamic parameters had been significantly improved in group A after CRT implantation ( P <0.05). In group B, NYHA classification and pulmonary hemodynamic parameters were decreased significantly ( P <0.05), but echocardiographic parameters did not change obviously ( P >0.05). There were no significant changes in NYHA classification, echocardiographic and pulmonary hemodynamic parameters in group C ( P >0.05). Compared with group C, group A and group B had lower all-cause mortality ( P =0.005) and lower incidence of composite endpoint events ( P =0.001)., Conclusions: Patients with LVRR and clinical response after CRT have a good prognosis. Patients with clinical response but without LVRR have a better prognosis than those without clinical response and LVRR, which may be related to the decrease of pulmonary hemodynamic parameters such as mPAP and TPG.

Introduction: Left ventricular ejection fraction (LVEF) ≤35%, as current significant implantable cardioverter-defibrillator (ICD) indication for primary prevention of sudden cardiac death (SCD) in heart failure (HF) patients, has been widely recognised to be inefficient. Improvement of patient selection for low LVEF (≤35%) is needed to optimise deployment of ICD. Most of the existing prediction models are not appropriate to identify ICD candidates at high risk of SCD in HF patients with low LVEF. Compared with traditional statistical analysis, machine learning (ML) can employ computer algorithms to identify patterns in large datasets, analyse rules automatically and build both linear and non-linear models in order to make data-driven predictions. This study is aimed to develop and validate new models using ML to improve the prediction of SCD in HF patients with low LVEF., Methods and Analysis: We will conduct a retroprospective, multicentre, observational registry of Chinese HF patients with low LVEF. The HF patients with LVEF ≤35% after optimised medication at least 3 months will be enrolled in this study. The primary endpoints are all-cause death and SCD. The secondary endpoints are malignant arrhythmia, sudden cardiac arrest, cardiopulmonary resuscitation and rehospitalisation due to HF. The baseline demographic, clinical, biological, electrophysiological, social and psychological variables will be collected. Both ML and traditional multivariable Cox proportional hazards regression models will be developed and compared in the prediction of SCD. Moreover, the ML model will be validated in a prospective study., Ethics and Dissemination: The study protocol has been approved by the Ethics Committee of the First Affiliated Hospital of Nanjing Medical University (2017-SR-06). All results of this study will be published in international peer-reviewed journals and presented at relevant conferences., Trial Registration Number: ChiCTR-POC-17011842; Pre-results., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2018. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Cardiac resynchronization therapy (CRT) is the standard-of-care therapy for the patients with heart failure and left ventricular (LV) dyssynchrony. However, approximately 30% of the patients show no response. Recent studies have shown that His bundle pacing (HBP) could be an alternative for the patients with CRT indications. The purpose of this study was to evaluate the efficacy of HBP in patients with heart failure., Methods: We searched PubMed and Embase databases for studies evaluating HBP in patients with heart failure and LV dyssynchrony. The successful rate of implantation, QRS duration, pacing threshold, LV function at baseline and follow-up, and mortality rates were extracted and summarized., Results: Eleven studies including 494 patients were included in this analysis. The overall successful rate for implantation was 82.4%. The main indications for HBP were CRT candidates and cardiomyopathy with atrial fibrillation undergoing atrioventricular node ablation. Permanent HBP resulted in narrow QRS duration of 116.3 ± 13.9 ms after implantation. LV functions, including echocardiographic parameters and clinical outcomes, significantly improved at follow-up (P < 0.001). However, there was a trend of increased capture and bundle branch block correction thresholds at follow-up compared to baseline (P = 0.01 and 0.02, respectively). During a mean follow-up of 23.7 months, 5.9% of the patients experienced heart failure-related hospitalization and the mortality rate was 9.1%., Conclusion: Permanent HBP has shown promising results for heart failure patients in small observational studies. Randomized controlled trials are needed to assess the efficacy of HBP in these patients., (© 2018 Wiley Periodicals, Inc.)

Background: The incidence and clinical outcomes of delayed response to cardiac resynchronization therapy (CRT) have not been well clarified. We aimed to observe the incidence and prognosis of delayed response and to identify its possible mechanisms., Methods: A total of 115 CRT patients were retrospectively analyzed in our study. Patients who met the enrollment criteria were divided into two groups: group A, conventional responders who showed response at 1-year follow-up, and group B, delayed responders who showed response after 1-year follow-up. CRT response was defined as an absolute increase of ≥10% in left ventricular ejection fraction., Results: Fifty-two patients (61 ± 12 years, 37 male) experienced conventional response to CRT and 17 patients (63 ± 11 years, 10 male) experienced delayed response. The mean follow-up time was 5.2 ± 2.4 years. The incidence of delayed response was 14.8% (17/115). All-cause mortality and hospitalization rates for heart failure were similar for delayed and conventional responders. Multivariate logistic regression analysis revealed that scar burden > 35% was an independent predictor of CRT delayed response (odds ratio 8.794, P  =  0.038)., Conclusions: A significant proportion of patients demonstrated delayed response to CRT. The delayed responders had a good prognosis that was similar to that of conventional responders. More scar burden might be related to the incidence of delayed response., (© 2017 Wiley Periodicals, Inc.)

Background: Implantable cardioverter defibrillators (ICDs) have become the standard approach for prevention of sudden cardiac death. Whether ICD therapy is an independent predictor of all-cause mortality is controversial. We made the systematic review and meta-analysis to estimate the impact of ICD therapy on mortality., Methods: We searched the PubMed and Embase databases for studies evaluating the effect of ICD shocks or antitachycardia pacing (ATP) on mortality. Hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated using random effects models., Results: Thirteen cohort studies were identified. Mean ejection fraction of the population was 23-35%; 68.0% had ischemic etiology, and 74.5% received a primary prevention ICD implantation. Appropriate shocks were an independent predictor of increased mortality compared with no-shock or no-therapy patients (HR 2.07, 2.76, respectively). In contrast, inconsistent results were obtained during inappropriate-shock analyses: when compared with no-shock patients, inappropriate shocks were associated with an increased risk of death (HR 1.54, 95% CI: 1.25-1.89, P < 0.0001); however, when compared to no-therapy patients, there was no relationship between inappropriate shocks and mortality (HR 1.20, 95% CI: 0.90-1.61, P = 0.22). Subgroup analysis in heart failure patients also did not find any difference in mortality between inappropriate-shock and no-therapy patients. No increased risk of mortality was found in the patients who experienced appropriate or inappropriate ATP only., Conclusion: Appropriate shocks were associated with an increased mortality in ICD patients. However, whether inappropriate shocks worsened the clinical outcome was controversial, and larger prospective trials are needed to clarify the issue., (©2015 Wiley Periodicals, Inc.)

β2-AR activation increases the risk of sudden cardiac death (SCD) in heart failure (HF) patients. Non-selective β-AR blockers have greater benefits on survival than selective β1-AR blockers in chronic HF patients, indicating that β2-AR activation contributes to SCD in HF. This study investigated the role of β2-AR activation on repolarization and ventricular arrhythmia (VA) in the experimental HF model. The guinea pig HF was induced by descending aortic banding. The effective refractoriness period (ERP), corrected QT (QTc) and the incidence of VA were examined using Langendorff and programmed electrical stimulation. Ikr and APD were recorded by the whole cell patch clamp. Selective β2-AR agonist salbutamol significantly increased the incidence of VA, prolonged QTc and shortened ERP. These effects could be prevented by the selective β2-AR antagonist, ICI118551. Salbutamol prolonged APD90 and reduced Ikr in guinea pig HF myocytes. The antagonists of cAMP (Rp-cAMP) and PKA (KT5720) attenuated Ikr inhibition and APD prolongation induced by salbutamol. However, the antagonists of Gi protein (PTX) and PDE III (amrinone) showed opposite effects. This study indicates that β2-AR activation increases the incidence of VA in the experimental HF model via activation of Gs/cAMP/PKA and/or inhibition of Gi/PDE pathways.

Background: Cardiac resynchronization therapy (CRT) is a standard treatment for selected patients with chronic heart failure (HF). However, up to 30%-50% of patients still do not respond to CRT.Objective: Our aim was to identify the predictive value of an S wave in lead V6 in CRT response in patients with complete left bundle branch block (CLBBB).Methods: The CLBBB definition included the Strauss left bundle branch block criteria and the absence of q waves in leads I, V5, and V6. According to the electrocardiogram at baseline, CLBBB patients were divided into 3 groups: T-CLBBB group (CLBBB without an S wave in lead V5 or V6), V5S group (CLBBB with an S wave in lead V5 and no S wave in lead V6), and V5&V6S group (CLBBB with S waves in leads V5 and V6). CRT response was defined as left ventricular end-systolic volume reduction ≥ 15% at 6-month follow-up. The combined end point included HF rehospitalization or all-cause death.Results: Of 181 patients with left bundle branch block-like pattern, 112 patients with CLBBB were included into 3 groups: 54 in the T-CLBBB group, 32 in the V5S group, and 26 in the V5&V6S group. The CRT response rate was 85.2% (46), 65.6% (21), and 38.5% (10), respectively (P < .001). Kaplan-Meier curves demonstrated that patients in the V5&V6S group had a higher incidence of HF rehospitalization or all-cause death than those in the other 2 groups (P < .001). In a multivariate logistic regression model analysis, an S wave in lead V6 was significantly associated with CRT nonresponse (hazard ratio 0.33; 95% confidence interval 0.11-0.96; P = .042).Conclusion: An S wave in lead V6 can predict poor response to CRT and long-term outcome. [ABSTRACT FROM AUTHOR]