Left bundle branch pacing versus left ventricular septal pacing as a primary procedural endpoint during left bundle branch area pacing: Evaluation of two different implant strategies.

INTRODUCTION: Implant procedure features and clinical implications of left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP) have not been yet fully described. We sought to compare two different left bundle branch area pacing (LBBAP) implant strategies: the first one accepting LVSP as a procedural endpoint and the second one aiming at achieving LBBP in every patient in spite of evidence of previous LVSP criteria. METHODS: LVSP was accepted as a procedural endpoint in 162 consecutive patients (LVSP strategy group). In a second phase, LBBP was attempted in every patient in spite of achieving previous LVSP criteria (n = 161, LBBP strategy group). Baseline patient characteristics, implant procedure, and follow-up data were compared. RESULTS: The final capture pattern was LBBP in 71.4% and LVSP in 24.2% in the LBBP strategy group compared to 42.7% and 50%, respectively, in the LVSP strategy group. One hundred and eighty-four patients (57%) had proven LBB capture criteria with a significantly shorter paced QRS duration than the 120 patients (37%) with LVSP criteria (115 ± 9 vs. 121 ± 13 ms, p < .001). Implant parameters were comparable between the two strategies but the LBBP strategy resulted in a higher rate of acute septal perforation (11.8% vs. 4.9%, p = .026) without any clinical sequelae. Patients with CRT indications significantly improved left ventricular ejection fraction (LVEF) during follow-up irrespective of the capture pattern (from 35 ± 11% to 45 ± 14% in proven LBBP, p = .024; and from 39 ± 13% to 47 ± 12% for LVSP, p = .003). The presence of structural heart disease and baseline LBBB independently predicted unsuccessful LBB capture. CONCLUSION: The LBBP strategy was associated with comparable implant parameters than the LVSP strategy but resulted in higher rates of septal perforation. Proven LBB capture and LVSP showed comparable effects on LVEF during follow-up.

Comparison of clinical outcomes between transthoracic echocardiography- and X-ray-guided left bundle branch pacing for bradycardia: A randomized controlled trial.

INTRODUCTION: Left bundle branch pacing (LBBP) is a physiological pacing modality. However, the long procedure and fluoroscopy time of LBBP is still a problem. This study aims to compare the clinical outcomes between transthoracic echocardiography (TTE)- and X-ray-guided LBBP. METHODS: This is a single-center, prospective, randomized controlled study. Consecutive patients who underwent LBBP in our team from June 2022 to November 2022 were enrolled. Procedure and fluoroscopy time, pacing parameters, electrophysiological and echocardiographic characteristics, as well as complications were recorded at implantation and during follow-up. RESULTS: In this study, 60 patients were enrolled and divided into two groups: 30 patients were allocated to the X-ray group and the remaining 30 to the TTE group. There was no significant difference in the success rate between the two groups (86.7% vs. 76.7%, p = .317). The procedure time of TTE group was comparable to that of the X-ray group (9.0 vs. 12.0 min, p = .063). However, the fluoroscopy time in the TTE group was significantly lower than that of the X-ray group (2.5 vs. 5.0 min, p = .002). There were no statistically significant differences in pacing parameters, electrophysiological and echocardiographic characteristics, or complications between the two groups at implantation and during follow-up. CONCLUSION: TTE-guided LBBP is a feasible and safe method. Compared with X-ray, TTE showed a comparable success rate and procedure time, but it could significantly reduce the fluoroscopy time of LBBP.

Prognostic benefits of His-Purkinje capture in physiological pacemakers for bradycardia.

INTRODUCTION: Clinical outcomes of long-term ventricular septal pacing (VSP) without His-Purkinje capture remain unknown. This study evaluated the differences in clinical outcomes between conduction system pacing (CSP), VSP, and right ventricular pacing (RVP). METHODS: Consecutive patients with bradycardia indicated for pacing from 2016 to 2022 were prospectively followed for the clinical endpoints of heart failure (HF)-hospitalizations and all-cause mortality at 2 years. VSP was defined as septal pacing due to unsuccessful CSP implant or successful CSP followed by loss of His-Purkinje capture within 90 days. RESULTS: Among 1016 patients (age 73.9 ± 11.2 years, 47% female, 48% atrioventricular block), 612 received RVP, 335 received CSP and 69 received VSP. Paced QRS duration was similar between VSP and RVP, but both significantly longer than CSP (p < .05). HF-hospitalizations occurred in 130 (13%) patients (CSP 7% vs. RVP 16% vs. VSP 13%, p = .001), and all-cause mortality in 143 (14%) patients (CSP 7% vs. RVP 19% vs. VSP 9%, p < .001). The association of pacing modality with clinical events was limited to those with ventricular pacing (Vp) > 20% (pinteraction < .05). Adjusting for clinical risk factors among patients with Vp > 20%, VSP (adjusted hazard ratio [AHR]: 4.74, 95% confidence interval [CI]: 1.57-14.36) and RVP (AHR: 3.08, 95% CI: 1.44-6.60) were associated with increased hazard of HF-hospitalizations, and RVP (2.52, 95% CI: 1.19-5.35) with increased mortality, compared to CSP. Clinical endpoints did not differ between VSP and RVP with Vp > 20%, or amongst groups with Vp < 20%. CONCLUSION: Conduction system capture is associated with improved clinical outcomes. CSP should be preferred over VSP or RVP during pacing for bradycardia.

The association between paced left ventricular activation time and cardiac reverse remodeling in heart failure patients with left bundle branch block.

INTRODUCTION: The association between paced LVAT and cardiac structure and function at baseline, as well as whether longer LVAT is associated with worse cardiac reverse remodeling in patients with heart failure (HF) and left bundle branch block (LBBB) has not been well investigated. The purpose of this study is to investigate the association between paced LVAT and baseline echocardiographic parameters and cardiac reverse remodeling at follow-up. METHODS: Patients with HF and LBBB receiving successful left bundle branch pacing (LBBP) from June 2018 to April 2023 were enrolled and grouped based on paced LVAT. NT-proBNP and echocardiographic parameters were recorded during routine follow-up. The relationships between paced LVAT and echocardiographic parameters at baseline and follow-up were analyzed. RESULTS: Eighty-three patients were enrolled (48 males, aged 65 ± 9.8, mean LVEF 32.1 ± 7.5%, mean LVEDD 63.0 ± 8.5 mm, median NT-proBNP 1057[513-3158] pg/mL). The paced QRSd was significantly decreased (177 ± 17.9 vs. 134 ± 18.5, p < .001) and median paced LVAT was 80[72-88] ms. After a median follow-up of 12[9-29] months, LVEF increased to 52.1 ± 11.2%, LVEDD decreased to 52.6 ± 8.8 mm, and NT-proBNP decreased to 215[73-532]pg/mL. Patients were grouped based on paced LVAT: LVAT < 80 ms (n = 39); 80 ≤ LVAT < 90 ms (n = 24); LVAT ≥ 90 ms (n = 20). Patients with longer LVAT had larger LVEDD and lower LVEF (LVEDDbaseline: p < .001; LVEFbaseline: p = .001). The difference in LVEF6M was statistically significant among groups (p < .001) and patients with longer LVAT had lower LVEF6M, while the difference in LVEF1Y was not seen (p = .090). There was no significant correlation between ΔLVEF6M-baseline, ΔLVEF1Y-6M and LVAT respectively (ΔLVEF6M-baseline: p = .261, r = -.126; ΔLVEF1Y-6M: p = .085, r = .218). CONCLUSION: Long paced LVAT was associated with worse echocardiographic parameters at baseline, but did not affect the cardiac reverse remodeling in patients with HF and LBBB. Those with longer LVAT required longer time to recover.

Conduction system pacing: how far are we from the "electrical" bypass?

Conduction system pacing is an alternative practice to conventional right ventricular apical pacing. It is a method that maintains physiologic ventricular activation, based on a correct pathophysiological basis, in which the pacing lead bypasses the lesion of the electrical fibers and the electrical impulse transmits through the intact adjacent conduction system. For this reason, it might be reasonably characterized by the term "electrical bypass" compared to the coronary artery bypass in revascularization therapy. In this review, reference is made to the sequence of events in which conventional right ventricular pacing may cause adverse outcomes. Furthermore, there is a reference to alternative strategies and pacing sites. Interest focuses on the modalities for which there are data from the literature, namely for the right ventricular (RV) septal pacing, the His bundle pacing (HBP), and the left bundle branch pacing (LBBP). A more extensive reference is about the HBP, for which there are the most updated data. We analyze the considerations that limit HBP-wide application in three axes, and we also present the data for the implantation and follow-up of these patients. The indications with their most important studies to date are then described in detail, not only in their undoubtedly positive findings but also in their weak aspects, because of which this pacing mode has not yet received a strong recommendation for implementation. Finally, there is a report on LBBP, focusing mainly on its points of differentiation from HBP.

Helix breakage during left bundle pacing area implantation.

A left bundle pacing stimulation pacemaker was implanted using stylet driver lead. The screw incarceration occurred after positioning of the lead. The screw rupture occurred during lead retraction; the distal portion of the screw remained incarcerated at the interventricular septum.

A shorter R wave peak time in left bundle branch pacing may not be a marker of more physiological ventricular activation: A case report.

Left bundle branch pacing (LBBp) is a promising alternative to conventional biventricular pacing cardiac resynchronization therapy. The left anterior fascicle (LAF) is adjacent to the left ventricular outflow tract, while the left posterior fascicle (LPF) dominates a broader area of the left ventricle. Whether LAF or LPF dominates ventricular activation has not been determined. We present the case of a 76-year-old man who underwent LBBp implantation and propose the left ventricular activation domination in LPF pacing, an alternative when LBBp is unavailable.

Gradual development of left bundle branch current of injury during left bundle branch pacing lead implantation.

A larger left bundle branch (LBB) potential or LBB current of injury (COI) indicates a low LBB capture threshold in LBB pacing. During LBB pacing in an 85-year-old woman, achieving a low LBB capture threshold did not initially present with a larger LBB potential or LBB COI, but rather with a new initial negative deflection in a ventricular electrogram. LBB COI gradually developed over 7 min thereafter, which suggested that the lead tip had reached the left ventricular subendocardium. Therefore, this negative deflection may be the first sign to avoid further lead rotation.

An interesting dynamic retrograde His bundle potential during the transventricular-septal process for left bundle branch pacing in a patient with right bundle branch block: A case report.

A 67-year-old male presented with symptomatic bradycardia caused by atrial fibrillation and underwent His bundle pacing (HBP) and left bundle branch pacing (LBBP). Electrocardiography (ECG) revealed a complete right bundle branch block (RBBB). John Jiang's connecting cable was used during the transventricular septal process. An interesting dynamic retrograde His bundle potential (RHP) was recorded with uninterrupted lead screws.

Successful direct pacing of the left bundle branch area with ICD lead using steerable delivery sheath.

Recently, conduction system pacing has been performed in patients with impaired cardiac function. We report a case in which a DF4 implantable cardioverter defibrillator lead was screwed directly into the left bundle branch area with the support of a steerable delivery sheath.

Use of cardiac contractility modulation combined with left bundle branch pacing CRT-P in a female with a 22-year history of non-ischemic dilated cardiomyopathy: A case report.

Cardiac contractility modulation (CCM) is a novel device-based therapy used to treat patients with heart failure with reduced ejection fraction (HFrEF). In both randomized clinical trials and real-life studies, CCM has been shown to improve exercise tolerance and quality of life, reverse left ventricular remodeling, and reduce hospitalization in patients with HFrEF. In this case report, we describe for the first time the use of CCM combined with left bundle branch pacing (LBBP) cardiac resynchronization therapy pacemaker (CRT-P) implantation therapy in a female with a 22-year history of non-ischemic dilated cardiomyopathy. With the optimal medical therapy and cardiac resynchronization therapy (CRT) strategies, the patient's quality of life initially recovered to some extent, but began to deteriorate in the past year. Additionally, heart transplantation was not considered due to economic reasons and late stage systolic heart failure. This is the first case of CCM implantation in Fujian Province and the first report of a combined CCM and left bundle branch pacing CRT-P implantation strategy in a patient with non-ischemic etiology dilated cardiomyopathy in China.

Left bundle branch pacing guide by uninterrupted recording of intrinsic filtered and unfiltered intracardiac electrograms.

BACKGROUND: Currently, the interrupted recording technique is commonly used to perform left bundle branch (LBB) pacing (LBBP). However, this method requires repeated testing to confirm that the LBB is captured and perforations are avoided. An automated solution may make this repetitive work easier. CASE SUMMARY: LBBP was performed using an uninterrupted recording technique in an 86-year-old woman. Lead position and LBB capture was confirmed by the characteristics of the intrinsic filtered and unfiltered intracardiac electrograms. CONCLUSION: Continuous mapping and recording technique may help achieve more accurate positioning of LBBP lead in the ventricular septum.

Ventricular dyssynchrony imaging, echocardiographic and clinical outcomes of left bundle branch pacing and biventricular pacing.

BACKGROUND: Left bundle branch pacing (LBBP) is a novel physiological pacing technique which may serve as an alternative to cardiac resynchronization therapy (CRT) by biventricular pacing (BVP). This study assessed ventricular activation patterns and echocardiographic and clinical outcomes of LBBP and compared this to BVP. METHODS: Fifty consecutive patients underwent LBBP or BVP for CRT. Ventricular activation mapping was obtained by ultra-high-frequency ECG (UHF-ECG). Functional and echocardiographic outcomes and hospitalization for heart failure and all-cause mortality after one year from implantation were evaluated. RESULTS: LBBP resulted in greater resynchronization vs BVP (QRS width: 170 ± 16 ms to 128 ± 20 ms vs 174 ± 15 to 144 ± 17 ms, p = 0.002 (LBBP vs BVP); e-DYS 81 ± 17 ms to 0 ± 32 ms vs 77 ± 18 to 16 ± 29 ms, p = 0.016 (LBBP vs BVP)). Improvement in LVEF (from 28 ± 8 to 42 ± 10 percent vs 28 ± 9 to 36 ± 12 percent, LBBP vs BVP, p = 0.078) was similar. Improvement in NYHA function class (from 2.4 to 1.5 and from 2.3 to 1.5 (LBBP vs BVP)), hospitalization for heart failure and all-cause mortality were comparable in both groups. CONCLUSIONS: Ventricular dyssynchrony imaging is an appropriate way to gain a better insight into activation patterns of LBBP and BVP. LBBP resulted in greater resynchronization (e-DYS and QRS duration) with comparable improvement in LVEF, NYHA functional class, hospitalization for heart failure and all-cause mortality at one year of follow up.

The interventricular conduction delays guide best cardiac resynchronization therapy: A tailored-patient approach to perform a CRT through Conduction System Pacing.

Evaluation of conduction intervals to predict success of resynchronization in biventricular pacing(BiVP) or Conduction System Pacing(CSP) is not spread in clinical practice. A right ventricle-to-left ventricle intrinsic conduction interval (RVs-LVs) > 70 ms or prolonged RVpaced - LVs(RVp-LVs)interval can predict Cardiac Resynchronization Therapy (CRT)response.This paper describes a case of cardiac resynchronization guided by spontaneous and paced interventricular conduction delays (IVCD) obtained in BiVP that led to changing intraoperative approach. A strategy for cardiac resynchronization based on the CSP/BiVP approach according to the IVCD could represent a viable and reliable solution to obtain a narrow paced QRS and to improve the CRT response.

Is left bundle branch pacing (LBBP) associated with better depolarization and repolarization kinetics than right ventricular mid septal pacing (RVSP)? - Comparison of frontal QRS -T angle in patients with LBBP, RVSP and normal ventricular conduction.

AIMS: To assess the frontal QRS- T angle (f QRS- T angle) in patients with left bundle branch pacing (LBBP) as compared to right ventricular mid septal pacing (RVSP) implanted for symptomatic high degree atrioventricular (AV) block and to compare with control subjects with normal ventricular conduction (CSNVC) METHODS: A total of one-fifty subjects were chosen (50 patients with LBBP, 50 patients with RVSP and 50 CSNVC). The indication for pacemaker implantation was symptomatic high degree AV block. Baseline clinical and electrocardiogram (ECG) parameters like QRS duration (QRSD), QRS axis and f QRS-T angle and Ejection Fraction (EF) were assessed. f QRS-T angle was measured as the difference between the computerised mean frontal QRS and T wave axes in the limb leads. If the difference between the QRS axis and T-wave axis exceeds 180°, then the resultant QRS-T angle would be calculated as 360° minus the absolute angle to obtain a value between 0° and 180°. Baseline, immediate post procedural and 6 month follow up (f/u) ECGs and EF were chosen for the analysis. RESULTS: Patients who underwent LBBP had significantly shorter paced QRSD than patients who had undergone RVSP (112 ± 12 ms vs 146 ± 13 ms; 95 % confidence interval (CI): 43, -31; p<0.001). There was no significant difference in the QRSD before and after LBBP. The QRSD before and after pacing in RVSP was 111 ± 27 ms and 146 ± 13 ms; 95 % CI: 43, -28; p < 0.001. The QRSD in control patients with NVC was 82.94 ± 9.59 ms. RVSP was associated with wider f QRS-T angle when compared with LBBP (103 ± 53° vs 82 ± 43°; 95 % CI: 39, -1.0; p = 0.037). The baseline and immediate post procedure f QRS-T angle in LBBP was 70 ± 48° and 82 ± 43°; 95 % CI: 31, 5.3; p = 0.2. At 6 months f/u, the f QRS-T angle was 61 ± 43°; 95 % CI: 8.5, 35; p=0.002. The baseline and immediate post procedure f QRS-T angle in RVSP was 67 ± 51° and 103 ± 53°; 95 % CI: 54, -17; p < 0.001. At 6 months f/u, the f QRS-T angle in RVSP group was 87 ± 58°; 95 % CI: 2.6, 29; p = 0.020. The f QRS T angle in control patients with NVC was 24 ± 16°. When subgroup analysis was done the difference in the f QRS-T angle was significant between RVSP and LBBP groups only in patients who had wide QRS escape. The mean LVEF at 6-month follow-up in LBBP vs RVSP was 61 ± 3.7 % vs 57.1 ± 7.8 %; 95 % CI:1.48, 6.32, p = 0.002. In the RVSP group, three patients developed pacing induced cardiomyopathy (PIC) whereas no patients in the LBBP group developed PIC at 6-month follow-up; p=0.021. One patient with PIC had deterioration of functional status with new onset HF symptoms. The patient symptoms improved with medical therapy and needed no hospitalisation. The patient declined further interventions including upgradation to CRT or LBB pacing. No deaths or ventricular arrhythmias were observed during the study period. CONCLUSION: LBBP is associated with narrower f QRS-T angle as compared to RVSP both at post implant period and at 6 month f/u period. These findings might be due to the more physiological depolarization and repolarization kinetics associated with LBBP. RVSP was associated with 6 % incidence of PIC. Hence wide f QRS-T angle might be a predictor of PIC.

Left bundle fascicular versus left bundle trunk pacing: A comparison of their electrical synchrony parameters.

BACKGROUND: Variation in human left bundle branch (LBB) anatomy has a significant effect on the sequence of left ventricular depolarization. However, little is known regarding the electrophysiological characteristics of pacing different LBB fascicles. OBJECTIVE: We aimed to analyse the different electrocardiographic characteristics of LBB pacing (LBBP) attending to the site of pacing at the LBB system. METHODS: In 200 consecutive patients with confirmed LBBP, we distinguished left bundle trunk capture (LBTP) from any LB fascicular pacing (LBFP) based on the presence of LB potentials and paced QRS morphologies. We compared them regarding procedure, LBBP criteria and electrical synchrony parameters. RESULTS: One hundred and seventy-three patients with LBFP were compared to 25 patients with LBTP. Left septal and posterior fascicles were significantly more prevalent than left anterior in LBFP (46.8 %, 41.0 % and 12.2 % respectively). QRS transition criteria (80.0 % vs 61.8 %; p = 0.077), selective LBBP (40.0 vs 21.5 %; p = 0.101), paced QRS width (110.3 ± 16.8 ms vs 115.4 ± 14.9 ms; p = 0.117), V6-RWPT (79.2 ± 10.7 ms vs 75.3 ± 9.7 ms; p = 0.068) and interpeak interval (42.5 ± 19.1 ms vs 45.7 ± 12.9 ms; p = 0.282) were not significantly different between LBTP and LBFP. All short-term complications occurred in LBFP, mainly driven by septal perforations (n = 23), without any difference in the pacing parameters. Among the LBFP subgroups, only aVL-RWPT was longer when the posterior fascicle was paced. CONCLUSIONS: LBFP is much more prevalent than LBTP in unselected consecutive patients with LBBP. LBFP seems more feasible, and as good as LBTP in terms of electrical synchrony and pacing safety.

Comparison of the efficacy of combining left bundle branch pacing with either sacubitril/valsartan or enalapril in the treatment of chronic heart failure: A retrospective observational analysis.

Objective: To assess the efficacy of left bundle branch pacing (LBBP) combined with either sacubitril/valsartan or enalapril in the treatment of chronic heart failure (CHF). Methods: We retrospectively reviewed the records of 138 patients with CHF admitted to Dazhou Central Hospital between June 2020 and June 2022 to extract clinical data. We divided the data into two treatment groups for the analysis: 71 patients received LBBP combined with sacubitril/valsartan treatment (sacubitril/valsartan group), and 67 received LBBP combined with enalapril treatment (enalapril group). The levels of cardiac and cardiopulmonary function indicators, levels of myocardial injury markers, and the scores of the Minnesota Living with Heart Failure Questionnaire (MLHFQ) before and after the treatment were compared between the two groups. Results: After six months of treatment, patients in the sacubitril/valsartan group had lower myocardial injury markers, higher cardiopulmonary function indicators, and lower MLHFQ scores (P<0.05). Conclusions: In CHF patients, the combination of LBBP with sacubitril/valsartan had a better therapeutic effect compared to LBBP with enalapril, with more effective improvement of the cardiopulmonary function, reduction of myocardial injury, and improvement in quality of life.

A novel approach for developing left bundle branch pacing and left bundle branch block in a canine model.

BACKGROUND AND OBJECTIVE: Left bundle branch pacing (LBBP) has shown the benefits in the treatment of dyssynchronous heart failure (HF). The purpose of this study was to develop a novel approach for LBBP and left bundle branch block (LBBB) in a canine model. METHODS: A "triangle-center" method by tricuspid valve annulus angiography for LBBP implantation was performed in 6 canines. A catheter was then applied for retrograde His potential recording and left bundle branch (LBB) ablation simultaneously. The conduction system was stained to verify the "triangle-center" method for LBBP and assess the locations of the LBB ablation site in relation to the left septal fascicle (LSF). RESULTS: The mean LBB potential to ventricular interval and stimulus-peak left ventricular activation time were 11.8 ± 1.2 and 35.7 ± 3.1 ms, respectively. The average intrinsic QRS duration was 44.7 ± 4.7 ms. LBB ablation significantly prolonged the QRS duration (106.3 ± 8.3 ms, p < .001) while LBBP significantly shortened the LBBB-QRS duration to 62.5 ± 5.3 ms (p < .001). After 6 weeks of follow-up, both paced QRS duration (63.0 ± 5.4 ms; p = .203) and LBBB-QRS duration (107.3 ± 7.4 ms; p = .144) were unchanged when comparing to the acute phase, respectively. Anatomical analysis of 6 canine hearts showed that the LBBP lead-tip was all placed in LSF area. CONCLUSION: The new approach for LBBP and LBBB canine model was stable and feasible to simulate the clinical dyssynchrony and resynchronization. It provided a useful tool to investigate the basic mechanisms of underlying physiological pacing benefits.

Feasibility and safety of zero-fluoroscopy left bundle branch pacing: An initial experience.

INTRODUCTION: Left bundle branch pacing (LBBP) has emerged in recent years as a new pacing modality, providing patients with a narrower paced QRS than conventional pacing and stable pacing parameters. At the same time, there is a growing concern about the use of fluoroscopy in pacemaker implantations, given its harmful effects on both patients and operators. However, there are no prior experiences of zero-fluoroscopy in LBBP procedure. METHODS: We conducted an observational prospective study recruiting consecutive patients that underwent zero-fluoroscopy LBBP pacemaker implantation. A 6-month follow-up visit was programmed for every patient. The main goal of our study was to assess the efficacy, feasibility, and safety of the procedure. RESULTS: From January 2021 to February 2022, we included 10 patients, 8 males. The average age was 63 ± 4 years. The procedure was successful in all patients. We observed a significant reduction in paced QRS width compared with basal QRS width (149 ± 31.9 vs. 116 ± 15.6 ms, p = .02). All device parameters remained stable at 6-month follow-up: no significant differences in mean impedance (700.5 ± 136.4 vs. 494 ± 72.7 Ohm, p = .09), capture threshold (0.67 ± 0.2 vs. 0.83 ± 0.2 V @ 0.4 ms, p = .27) or endocardial V-wave amplitude (10.6 ± 5.2 vs. 13.9 ± 6.3 mV, p = .19). No complications were reported in any case. CONCLUSION: Zero-fluoroscopy LBBP is feasible and safe, and it may be considered in cases where radiation exposure is contraindicated or especially undesirable. Future randomized clinical trials are needed for the widespread use of this new technique.

Predictors of procedural failure of left bundle branch pacing in scarred left ventricle.

INTRODUCTION: Presence of scar at the implantation-site is considered as a major factor in determining the success of left bundle branch pacing (LBBP). We aimed at analyzing the predictors of procedural failure in patients with scarred-left ventricle (LV) as demonstrated by cardiac-magnetic resonance-imaging (CMR). METHODS: This was a retrospective, observational single-center-study that included consecutive cardiomyopathy patients with LV-scar as demonstrated by late-gadolinium-enhancement (LGE) in CMR requiring LBBP. Procedural-failure was defined as the inability to penetrate the septum to reach the LV subendocardium RESULTS: A total of 25 cardiomyopathy patients demonstrated LGE in CMR and were included in the study. LBBP was successful in 16 patients (group-I; 64% acute-procedural-success). In the remaining 9 patients (group-II) lead could not be penetrated and hence biventricular-pacing was done. LBBP resulted in reduction in QRS-duration and improvement in LV ejection fraction in group-I patients during a mean follow-up of 11.2 ± 3.7 months. Computed-tomography-angiography after LBBP showed the successful lead deployment site (LBBP-Zone) as the overlapping areas of inferior aspect of antero-septum and superior aspect of infero-septum (segment 2/3; AHA-model) in short-axis view(figure-1C). CMR showed LGE in significantly more number of LV-segments and high scar-burden in group-II as compared to group-I (figure-1). A total scar score value of >1.0 predicted failure with 100%-sensitivity and 75%-specificity. CMR revealed transmural-scar in the LBBP-Zone in all patients in group-II (n = 9; 100%). Transmural scar in LBBP-Zone by CMR had 100%-sensitivity and 100%-specificity for predicting the procedural-failure. CONCLUSION: CMR helps in predicting the procedural failure of LBBP in patients with scarred LV. Presence of transmural-LGE in the LBBP-Zone predicts failure with high sensitivity and specificity.