Arrhythmic Risk in Biventricular Pacing Compared With Left Bundle Branch Area Pacing: Results From the I-CLAS Study.

BACKGROUND: Left bundle branch area pacing (LBBAP) may be associated with greater improvement in left ventricular ejection fraction and reduction in death or heart failure hospitalization compared with biventricular pacing (BVP) in patients requiring cardiac resynchronization therapy. We sought to compare the occurrence of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) and new-onset atrial fibrillation (AF) in patients undergoing BVP and LBBAP. METHODS: The I-CLAS study (International Collaborative LBBAP Study) included patients with left ventricular ejection fraction ≤35% who underwent BVP or LBBAP for cardiac resynchronization therapy between January 2018 and June 2022 at 15 centers. We performed propensity score-matched analysis of LBBAP and BVP in a 1:1 ratio. We assessed the incidence of VT/VF and new-onset AF among patients with no history of AF. Time to sustained VT/VF and time to new-onset AF was analyzed using the Cox proportional hazards survival model. RESULTS: Among 1778 patients undergoing cardiac resynchronization therapy (BVP, 981; LBBAP, 797), there were 1414 propensity score-matched patients (propensity score-matched BVP, 707; propensity score-matched LBBAP, 707). The occurrence of VT/VF was significantly lower with LBBAP compared with BVP (4.2% versus 9.3%; hazard ratio, 0.46 [95% CI, 0.29-0.74]; P<0.001). The incidence of VT storm (>3 episodes in 24 hours) was also significantly lower with LBBAP compared with BVP (0.8% versus 2.5%; P=0.013). Among 299 patients with cardiac resynchronization therapy pacemakers (BVP, 111; LBBAP, 188), VT/VF occurred in 8 patients in the BVP group versus none in the LBBAP group (7.2% versus 0%; P<0.001). In 1194 patients with no history of VT/VF or antiarrhythmic therapy (BVP, 591; LBBAP, 603), the occurrence of VT/VF was significantly lower with LBBAP than with BVP (3.2% versus 7.3%; hazard ratio, 0.46 [95% CI, 0.26-0.81]; P=0.007). Among patients with no history of AF (n=890), the occurrence of new-onset AF >30 s was significantly lower with LBBAP than with BVP (2.8% versus 6.6%; hazard ratio, 0.34 [95% CI, 0.16-0.73]; P=0.008). The incidence of AF lasting >24 hours was also significantly lower with LBBAP than with BVP (0.7% versus 2.9%; P=0.015). CONCLUSIONS: LBBAP was associated with a lower incidence of sustained VT/VF and new-onset AF compared with BVP. This difference remained significant after adjustment for differences in baseline characteristics between patients with BVP and LBBAP. Physiological resynchronization by LBBAP may be associated with lower risk of arrhythmias compared with BVP.

Left bundle branch area pacing using a lumenless lead: A systematic literature review and meta-analysis.

BACKGROUND: Although left bundle branch area pacing (LBBAP) has been shown to be a feasible option for delivering physiological pacing, data are largely limited to single-center reports. The aim of this analysis was to systematically assess the safety and efficacy of LBBAP with the Model 3830 lead among primarily bradycardia patients. METHODS AND RESULTS: PubMed, Embase, Cochrane Library, and Google Scholar were searched for full-text articles on LBBAP using the SelectSecure Model 3830 lumenless lead. Rates and means were estimated using random- and mixed-effects models. Of 3395 articles, 53 met inclusion criteria, representing 6061 patients undergoing an implant attempt. Average patient age was 68.1 years (95% CI: 66.6, 69.6) and 53.1% were male (95% CI: 50.5%, 55.7%). The average implant success rate among bradycardia-indicated patients was 92.7% (95% CI: 89.5%, 94.9%). The overall estimated procedural adverse event rate was 2.5% (95% CI: 1.1%, 5.4%). The estimated septal perforation rate at implant was 1.6% (95% CI: 1.0%, 2.6%) with no adverse clinical sequelae reported. Pacing thresholds were low at implant (0.67 V [95% CI: 0.64, 0.70]) and remained stable through 12 months (0.76 V [95% CI: 0.72, 0.80]). Among bradycardia-indicated patients, LVEF remained stable from baseline to post-implant (59.5% [95% CI: 57.9%, 61.1%] vs. 60.1% [95% CI: 58.5%, 61.7%]). CONCLUSION: This meta-analysis including 6061 patients implanted with a Model 3830 lead for LBBAP found an average implant success rate of 92.7% and a procedural adverse event rate of 2.5% with stable electrical parameters and LVEF post-implant.

Result of the left bundle branch area pacing data collection registry, an international multicenter study of conduction system pacing with a Tendril STS 2088 stylet-driven lead.

INTRODUCTION: Left bundle branch area (LBBA) pacing (LBBAP) has been proposed as an alternative therapy option in patients indicated for cardiac pacing to treat bradycardia or heart failure. The aim of the study was to evaluate the safety and effectiveness of LBBAP in patients implanted with a Tendril 2088 stylet-driven lead. METHODS: The international retrospective data collection registry included 11 sites from 5 countries globally. Patients with attempted implants of the Tendril lead in the LBBA were followed for at least 6 months post the implant attempt. The primary safety and efficacy endpoints were freedom from LBBAP lead-related serious adverse events and the composite of LBBA capture threshold of ≤2.0 V and R-wave amplitudes ≥5 mV (or ≥value at implant), respectively. RESULTS: Of 221 patients with attempted implants of the Tendril 2088 lead in the LBBA, 91.4% (202/221) had successful implants for LBBAP. Regardless of the LBBAP implant success, all patients were followed for at least 6 months (8.7 ± 7.3 months). Baseline characteristics: 44% female, 84% ≥65 years old, 34% coronary artery disease, and 86% of primary indications for pacemaker implant. Both primary safety and effectiveness endpoints were met (freedom from LBBAP lead-related serious adverse device effects of 99.5% and electrical performance composite success rate of 93%). The capture thresholds in LBBAP at implant and 6 months were 0.8 ± 0.3 V@0.4 ± 0.1 ms and 0.8 ± 0.3 V@0.4 ± 0.1 ms. The rate of patients with capture threshold rise ≥1 V was 1.5% through 6 months. The R-wave amplitudes in LBBAP at implant and 6 months were 9.3 ± 3.2 mV and 10.6 ± 3.0 mV. CONCLUSIONS: This large multicenter study demonstrates that the stylet-driven Tendril™ STS 2088 lead is safe and effective for LBBAP with high success and low complication rates.

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.

Clinical outcomes of conduction system pacing versus biventricular pacing for cardiac resynchronization therapy: A systematic review and meta-analysis.

INTRODUCTION: Conduction system pacing (CSP) is observed to produce greater improvements in echocardiographic and hemodynamic parameters as compared to conventional biventricular pacing (BiVP). However, whether these surrogate endpoints directly translate to improvements in hard clinical outcomes such as death and heart failure hospitalization (HFH) with CSP remains uncertain as studies reporting these outcomes are scarce. The aim of this meta-analysis was to analyze the existing data to compare the clinical outcomes of CSP versus BiVP. METHODS: A systematic search of the Embase and PubMed database was performed for studies comparing CSP and BiVP for patients indicated to receive a CRT device. The coprimary endpoints were all-cause mortality and HFH. Other secondary outcomes included change in left ventricular ejection fraction (LVEF), change in NYHA class, and increase in NYHA class ≥1. A random-effects model was chosen a priori to analyze the composite effects given the anticipated heterogeneity of included trials. RESULTS: Twenty-one studies (4 randomized and 17 observational) were identified reporting either primary outcome and were included in the meta-analysis. In total 1960 patients were assigned to CSP and 2367 to BiVP. Median follow-up time was 10.1 months (ranging 2-33 months). CSP was associated with a significant reduction in all-cause mortality (odds ratio [OR] 0.68, 95% confidence interval [CI]: 0.56-0.83) and HFH (OR 0.52, 95% CI: 0.44-0.63). Mean improvement in LVEF was also greater with CSP (mean difference 4.26, 95% CI: 3.19-5.33). Reduction in NYHA class was significantly greater with CSP (mean difference -0.36, 95% CI: -0.49 to -0.22) and the number of patients with an increase in NYHA class ≥1 was significantly greater with CSP (OR 2.02, 95% CI: 1.70-2.40). CONCLUSIONS: CSP was associated with a significant reduction in all-cause mortality and HFH when compared to conventional BiVP for CRT. Further large-scale randomized trials are needed to verify these observations.

Right sided approach for left bundle branch pacing using lumen-less lead: Technical considerations and follow-up outcome.

INTRODUCTION: Left bundle branch pacing has gained significant momentum in the last few years. The procedure involves deploying the lead deep inside the interventricular septum through left subclavian vein. We aimed at analyzing the feasibility, efficacy and long-term outcome of left bundle branch pacing (LBBP) using lumen-less lead through the right subclavian vein. METHODS: This was a retrospective-institutional, single center observational study done in consecutive patients who underwent LBBP using 3830 selectsecuretm lead. Left subclavian venous access was the primary strategy for lead implantation. Patients requiring right sided approach due to venous obstruction or persistent left superior-vena-cava (PLSVC) for LBBP were included in the study. RESULTS: Right sided approach was successful in 16 out of 19 (84%) attempted patients. C315-His catheter was used in all patients without modifying its curvature. PLSVC (n = 7), left venous obstruction (n = 7), right sided device upgradation (n = 1) and left pocket infection (n = 1) were the reasons for right sided approach. Mean follow-up duration was 17 ± 12 months. LBBP resulted in reduction in QRS duration from 137.3 ± 37.8 ms to 122.3 ± 9.5 ms (p -.13) and increase in LV ejection fraction from 46.2 ± 16.3% to 54.4 ± 11.6% (p -.11). The mean fluoroscopy duration and radiation dose were significantly high in right sided approach (n = 16) as compared to left sided approach (n = 293). In patients requiring cardiac-resynchronization therapy (CRT), right sided LBBP resulted in reduction in QRS duration from 171.8 ± 18.5 to 125.5 ± 11.9 ms (p -.0001) and increase in LVEF from 29.1 ± 3.8 to 45.1 ± 11.9% (p -.005). CONCLUSION: Right sided LBBP is feasible, safe and effective in patients requiring pacing for symptomatic bradyarrhythmia and CRT. Further development in dedicated tools for right-sided approach would help in reducing the fluoroscopy-duration and radiation-dose.

Observations of interventricular septal behavior during left bundle branch pacing.

INTRODUCTION: Left bundle branch pacing (LBBP) involves the deployment of the lead deep inside the septum. Penetration of the septum by the lead depends on the texture of the septum, rapidity of rotations, operator experience, and implantation tools. OBJECTIVES: The aim of our study was to assess the behavior of the lumenless lead during rapid rotations and the physiological property of the interventricular septum(IVS) during LBBP. METHODS: Patients undergoing LBBP between January 2021 and December 2022 were retrospectively included in the study. RESULTS: Among 255 attempted patients, 20 (7.9%) had procedural failure(no LBB capture-four, inability to penetrate septum-seven, and dislodgements after sheath removal-nine). Septal penetration achieved in 248/255 patients (97.2%). Lead movement inside the IVS was assessed by lead traverse time. Based on the behavior of the IVS (n = 255), three different responses were noted. Type-I response(normal/firm septum) in 93.7% (n = 239) characterized by constant and progressive movement of lead. Neither perforation nor further change in premature-ventricular-complex morphology beyond M-beat were observed despite additional few unintentional rotations indicating the protective mechanism of LV-endocardium. Type-II response(soft/cheesy septum) in 3.5% (n = 9) characterized by hyper-movement of lead without resistance due to altered texture of septum and poor LV subendocardial barrier resulting in perforation. No patients in this group had LV dysfunction or associated coronary artery disease. In type-III response, seen in 2.8% (n = 7), lead could not be penetrated due to scar in IVS. CONCLUSION: Three different patterns of responses were observed during LBBP. The most distinct type-ll response was associated with soft/cheesy septum with hyper-movement of the lead predisposing for future dislodgments in patients without structural heart disease.

EHRA clinical consensus statement on conduction system pacing implantation: endorsed by the Asia Pacific Heart Rhythm Society (APHRS), Canadian Heart Rhythm Society (CHRS), and Latin American Heart Rhythm Society (LAHRS).

Conduction system pacing (CSP) has emerged as a more physiological alternative to right ventricular pacing and is also being used in selected cases for cardiac resynchronization therapy. His bundle pacing was first introduced over two decades ago and its use has risen over the last five years with the advent of tools which have facilitated implantation. Left bundle branch area pacing is more recent but its adoption is growing fast due to a wider target area and excellent electrical parameters. Nevertheless, as with any intervention, proper technique is a prerequisite for safe and effective delivery of therapy. This document aims to standardize the procedure and to provide a framework for physicians who wish to start CSP implantation, or who wish to improve their technique.

EHRA clinical consensus statement on conduction system pacing implantation: executive summary. Endorsed by the Asia-Pacific Heart Rhythm Society (APHRS), Canadian Heart Rhythm Society (CHRS) and Latin-American Heart Rhythm Society (LAHRS).

Conduction system pacing (CSP) has emerged as a more physiological alternative to right ventricular pacing and is also being used in selected cases for cardiac resynchronization therapy. His bundle pacing was first introduced over two decades ago and its use has risen over the last years with the advent of tools which have facilitated implantation. Left bundle branch area pacing is more recent but its adoption is growing fast due to a wider target area and excellent electrical parameters. Nevertheless, as with any intervention, proper technique is a prerequisite for safe and effective delivery of therapy. This document aims to standardize the procedure and to provide a framework for physicians who wish to start CSP implantation, or who wish to improve their technique. A synopsis is provided in this print edition of EP-Europace. The full document may be consulted online, and a 'Key Messages' App can be downloaded from the EHRA website.

Frontiers in conduction system pacing: treatment of long PR in patients with heart failure.

Patients with heart failure who have a prolonged PR interval are at a greater risk of adverse clinical outcomes than those with a normal PR interval. Potential mechanisms of harm relating to prolonged PR intervals include reduced ventricular filling and also the potential progression to a higher degree heart block. There has, however, been relatively little work specifically focusing on isolated PR prolongation as a therapeutic target. Secondary analyses of trials of biventricular pacing in heart failure have suggested that PR prolongation is both a prognostic marker and a promising treatment target. However, while biventricular pacing offers an improved activation pattern, it is nonetheless less physiological than native conduction in patients with a narrow QRS duration, and thus, may not be the ideal option for achieving therapeutic shortening of atrioventricular delay. Conduction system pacing aims to preserve physiological ventricular activation and may therefore be the ideal method for ventricular pacing in patients with isolated PR prolongation. Acute haemodynamic experiments and the recently reported His-optimized pacing evaluated for heart failure (HOPE HF) Randomised Controlled Trial demonstrates the potential benefits of physiological ventricular pacing on patient symptoms and left ventricular function in patients with heart failure.

Implant, assessment, and management of conduction system pacing.

His bundle pacing and left bundle branch pacing, together referred to as conduction system pacing, have (re)gained considerable interest over the past years as it has the potential to preserve and/or restore a more physiological ventricular activation when compared with right ventricular pacing and may serve as an alternative for cardiac resynchronization therapy. This review manuscript dives deeper into the implantation techniques and the relevant anatomy of the conduction system for both pacing strategies. Furthermore, the manuscript elaborates on better understanding of conduction system capture with its various capture patterns, its potential complications as well as appropriate follow-up care. Finally, the limitations and its impact on clinical care for both His bundle pacing and left bundle branch pacing are being discussed.

External irrigation of a non-irrigated ablation catheter for effective AV node ablation during conduction system pacing.

Ablation using non-irrigated catheter can lead to rapid rise in temperature of electrode tissue interface from tissue desiccation, steam and coagulum formation and this may limit power delivery and lesion size. We present a novel technique of external irrigation through the long sheath while using a non-irrigated ablation catheter during AV Node ablation and conduction system pacing. By bringing the long sheath closer to the tip of non-irrigated catheter and injecting cold normal saline allows cooling of electrode tissue interface leading to increase in power delivery resulting in a deeper lesion.

Axis deviation in nonischemic cardiomyopathy with left bundle branch block: Insights from left bundle branch pacing.

INTRODUCTION: Biventricular pacing has shown excellent results in patients with heart failure and left bundle branch block (LBBB). Studies have shown that the patients with abnormal axis deviation may benefit less from cardiac resynchronization therapy (CRT) as compared to those with the normal axis. The exact reason for left axis deviation (LAD) in LBBB is not known but could be due to diseased left anterior fascicle, left ventricular enlargement, or due to advanced electrical remodeling. METHODS: The aim of the study was to analyze the incidence of LAD in nonischemic cardiomyopathy (NICM) with LBBB and the clinical outcomes following left bundle branch pacing (LBBP). RESULTS: We have included 64 consecutive patients with NICM and LBBB, who underwent successful LBBP. Patients were divided into two groups-Group I with baseline normal axis (n = 40; 63%) and Group II with LAD (n = 24; 37%). The mean axis changed from +23.6 ± 28.8° at baseline to +16.5 ± 35.1° and from -40.4 ± 10.3° at baseline to 7.08 ± 41.1° after LBBP in Group I and Group II, respectively. LBBP retained the normal axis in 93% of Group I patients and normalized the axis in 75% of Group II patients. The percentage changes in QRS duration, left ventricular ejection fraction, and left ventricular end-diastolic diameter were similar in both the groups (+40% vs. +32%; p = .52, +64% vs. +50%; p = 0.34, -8% vs. -6%; p = .76, respectively). Capturing the proximal LBB would correct the LAD by recruitment of left anterior fascicles and pacing proximal to the site of the septal breakthrough of the right bundle branch activation wavefront during LBBB. CONCLUSION: LBBP as an alternative strategy for CRT could result in similar improvement in LBBB patients with LAD as in those with the normal axis.

M-beat-A novel marker for selective left bundle branch capture.

INTRODUCTION: Premature-ventricular-complexes (template/fixation beat) guided left bundle branch pacing (LBBP) was recently described as a novel method of successful lead deployment by rapid rotations. METHODS: We aimed at analyzing the incidence of a unique morphology template beat, which we labelled as 'M-beat' in patients undergoing PVC-guided LBBP, its ability to predict selective LBB-capture and clinical significance. RESULTS: Overall 210 out of 217 attempted-patients (96.7%) underwent successful LBBP. Template beat was noted in 90.4% patients (n = 190) and M-beat in 32.8%(n = 69). Non-selective to selective capture transition demonstrated in 55.2%(n = 116). The QRS duration of the M-beat was 129.3 ± 13.1ms. Patients were divided into two groups: Group-I with M-beat (n = 69;32.8%) and Group-II without M-beat (n = 141; 67.2%). The mean fluoroscopy-time was significantly less in group-I as compared to group-II (13.1 ± 11.1 vs 16.8 ± 12.04 minutes; p-0.03). Patients in group-II required more attempts as compared to group-I for successful lead deployment (2.8 ± 1.09 vs 2.2 ± 1.04; p - 0.01). Six patients showed loss of R-wave in lead-V1 and 2 showed rise in LBB capture threshold by >1V during follow-up in group-II. M-beat had a specificity of 96.77% and sensitivity of 58.62% (positive-predictive-value-98.55%) to predict selective-LBB capture. Myocardial excitability would not modify the occurrence of M-beat as opposed to capture transition response since it could be demonstrated without pacing protocols. When confirmation of LBB-capture itself would be difficult in patients with baseline LBBB-morphology, M-beat with 42.8% incidence predicted selective capture with 96.7% specificity and 66.04% sensitivity(positive-predictive-value-97.22%). CONCLUSION: M-beat is a marker of transient-selective LBB-capture, independent of the local myocardial excitability with high specificity and positive predictive value irrespective of the baseline QRS morphology.

Clinical outcomes of left bundle branch area pacing compared to His bundle pacing.

INTRODUCTION: His bundle pacing (HBP) is the most physiologic form of pacing and has been associated with reduced risk for heart failure hospitalization (HFH) and mortality compared to right ventricular pacing. Left bundle branch area pacing (LBBAP) is a safe and effective alternative option for patients needing ventricular pacing. The aim of this study was to compare the clinical outcomes between LBBAP and HBP among a large cohort of patients undergoing permanent pacemaker implantation. METHODS: This observational registry included consecutive patients with AV block/AV node ablation who underwent de novo permanent pacemaker implantations with successful LBBAP or HBP between April 2018 and October 2020. The primary outcome was the composite endpoint of time to death from any cause or HFH. Secondary outcomes included the composite endpoint among patients with prespecified ventricular pacing burden and individual outcomes. RESULTS: The study population included 359 patients who met the inclusion criteria (163 in the HBP and 196 in the LBBAP group). Paced QRSd during LBBAP was similar to HBP (125 ± 20.2 vs. 126 ± 23.5 ms, p = .643). There were no statistically significant differences in the primary composite outcome in LBBAP (17.3%) compared to HBP (24.5%) (hazard ratio [HR]: 1.15, 95% CI: 0.72-1.82, p = .552). Secondary outcomes of death (10% vs. 17%; HR: 1.3, 95% CI: 0.73-2.33, p = .38) and HFH (10% vs. 12%; HR: 1.02, 95% CI: 0.54-1.94, p = .94) were not different among both groups. CONCLUSIONS: There were no statistically significant differences in the clinical outcomes of death or HFH in LBBAP when compared to HBP.

Conduction system pacing following septal myectomy: Insights into site of conduction block.

INTRODUCTION: Septal myectomy for obstructive hypertrophic cardiomyopathy (HCM) is associated with conduction block; however, the electrophysiological characteristics of conduction block have not been well characterized. The aim of study was to assess the feasibility and safety of His bundle pacing (HBP) and left bundle branch area pacing (LBBAP) in patients with septal myectomy-associated conduction block. METHODS AND RESULTS: Patients with HCM and indications for pacing or cardiac resynchronization therapy after septal myectomy were included. Electrophysiological mapping was performed to identify the site of block. The success rates and pacing characteristics of HBP and LBBAP were also recorded. The echocardiographic data and complications were documented and tracked during follow-up. Ten patients with atrioventricular block (AVB) or left bundle branch block (LBBB) post-myectomy were included in the study. The site of block was infranodal in the nine patients with AVB. HBP failed due to the lack of distal His bundle capture (N = 7) or LBBB correction (N = 3). LBBAP was successful in nine patients and failed in one. QRS duration narrowed from 163.3 ± 16.6 ms after surgery to 123.6 ± 15.8 ms during LBBAP (p < .001). The mean depth of the leads was 13.3 ± 4.0 mm (range from 10 to 20 mm). At a mean follow-up of 5.3 ± 3.9 months, pacing parameters and left ventricular ejection fraction remained stable. CONCLUSIONS: Electrophysiological mapping revealed that the site of block was infra-Hisian and not correctable with HBP in patients with HCM post-myectomy. LBBAP appears to be a more feasible physiological strategy for these patients.

Differentiating left bundle branch pacing and left ventricular septal pacing: An algorithm based on intracardiac electrophysiology.

BACKGROUND: Left bundle branch pacing (LBBP) is a new near-physiological pacing modality. Distinguishing left ventricular septal only pacing (LVSP) from nonselective LBBP still needs clarification. This prospective study sought to establish a differentiation algorithm to confirm LBBP. METHODS AND RESULTS: LBBP was attempted in consecutive patients. If direct LBB capture (LBBP) could not be confirmed, LVSP was considered to have been achieved. Intracardiac left ventricular (LV) activation sequence and activation time were analyzed using coronary sinus (CS) electrogram mapping. Electrophysiological parameters including S-CSmax, S-CSmin, LV lateral wall activation time, ΔLV, and LBB potential were compared between LBBP and LVSP. Stimulated LV activation time (S-LVAT) and stimulated QRS duration (S-QRSd) were also compared between the two groups. Multivariate logistic regression analysis was used to develop a prediction algorithm for LBBP. Of the 43 prospectively enrolled patients, 27 underwent LBBP and 16 underwent LVSP. All LBBP patients showed identical LV activation sequences to their intrinsic rhythm while no LVSP patients maintained their intrinsic sequence. S-CSmax, ΔLV, LV lateral wall activation time, and S-LVAT during LBBP were significantly shorter than those during LVSP. Combining LBB potential with S-LVAT had the largest area under the curve (AUC) of 0.985 for confirming LBBP with a sensitivity of 95.2% and a specificity of 93.7%. CONCLUSIONS: Compared with LVSP, LBBP preserves a normal LV activation sequence and better electrical synchrony. A combination of LBB potential with S-LVAT can be an effective and practical model to distinguish LBBP from LVSP during implantation in patients with normal LBB activation.

The V6-V1 interpeak interval: a novel criterion for the diagnosis of left bundle branch capture.

AIMS: We hypothesized that during left bundle branch (LBB) area pacing, the various possible combinations of direct capture/non-capture of the septal myocardium and the LBB result in distinct patterns of right and left ventricular activation. This could translate into different combinations of R-wave peak time (RWPT) in V1 and V6. Consequently, the V6-V1 interpeak interval could differentiate the three types of LBB area capture: non-selective (ns-)LBB, selective (s-)LBB, and left ventricular septal (LVS). METHODS AND RESULTS: Patients with unquestionable evidence of LBB capture were included. The V6-V1 interpeak interval, V6RWPT, and V1RWPT were compared between different types of LBB area capture. A total of 468 patients from two centres were screened, with 124 patients (239 electrocardiograms) included in the analysis. Loss of LVS capture resulted in an increase in V1RWPT by ≥15 ms but did not impact V6RWPT. Loss of LBB capture resulted in an increase in V6RWPT by ≥15 ms but only minimally influenced V1RWPT. Consequently, the V6-V1 interval was longest during s-LBB capture (62.3 ± 21.4 ms), intermediate during ns-LBB capture (41.3 ± 14.0 ms), and shortest during LVS capture (26.5 ± 8.6 ms). The optimal value of the V6-V1 interval value for the differentiation between ns-LBB and LVS capture was 33 ms (area under the receiver operating characteristic curve of 84.7%). A specificity of 100% for the diagnosis of LBB capture was obtained with a cut-off value of >44 ms. CONCLUSION: The V6-V1 interpeak interval is a promising novel criterion for the diagnosis of LBB area capture.

Minimally decremental atriofascicular accessory pathway with bidirectional conduction.

Atriofacicular pathways of Mahaim type are typically decrementally conducting accessory pathways without retrograde conduction properties, located on the right ventricular free wall at the tricuspid annulus. We report a patient with an atriofascicular pathway with minimal anterograde decremental conduction. Both long and short V-H antidromic atriofascicular reentrant tachycardias were induced and mechanism confirmed with electrophysiologic testing. Additionally, orthodromic atriofascicular reentrant tachycardia with narrow and right bundle branch block morphologies were inducible. Mahaim pathway was successfully ablated with elimination of both antidromic and orthodromic tachycardias.

Late dislodgement of left bundle branch pacing lead and successful extraction.

A 61-years-old male underwent left bundle branch pacing for nonischemic dilated cardiomyopathy with recurrent heart failure. Left bundle branch pacing (LBBP) resulted in reduction in QRS duration along with improvement in left ventricular ejection fraction (LVEF) to 64% during follow-up. Two years after implantation he had recurrence of symptoms along with decline in LVEF to 51%. Late lead dislodgement was diagnosed and re-do LBBP was planned. The lead was extracted en-masse without complication and a new 3830 lead was positioned deep inside the proximal septum to capture the left bundle. Postprocedure echocardiography showed no ventricular septal defect or damage to tricuspid leaflet.