Left bundle branch pacing lead for sensing ventricular arrhythmias in implantable cardioverter-defibrillator: A pilot study (LBBP-ICD study)

BACKGROUND

Left bundle branch pacing (LBBP) has been suggested as an alternative modality for biventricular pacing in cardiac resynchronization therapy (CRT)-eligible patients. As it provides stable R-wave sensing, LBBP has been recently used to provide sensing of ventricular arrhythmia in patients receiving implantable cardioverter-defibrillator (ICD) with CRT.

OBJECTIVE

The aim of this study was to analyze the long-term safety and efficacy of the LBBP lead for appropriate detection of ventricular arrhythmia and delivery of antitachycardia pacing (ATP) in patients requiring defibrillator therapy with CRT.

METHODS

CRT-eligible patients who underwent successful LBBP-optimized ICD and LBBP-optimized CRT with defibrillator were enrolled. The LBBP lead was connected to the right ventricular-P/S port after capping the IS-1 connector plug of the DF-1-ICD lead. LBBP-optimized ICD or LBBP-optimized CRT with defibrillator was decided on the basis of correction of conduction system disease. Documented arrhythmic episodes and therapy delivered were analyzed.

RESULTS

Thirty patients were enrolled. The mean age was 59.7 ± 10.5 years. LBBP resulted in an increase in left ventricular ejection fraction from 29.9% ± 4.6% to 43.9% ± 11.2% (P < .0001). During a mean follow-up of 22.9 ± 12.5 months, 254 ventricular arrhythmic events were documented. Appropriate events (n = 225 [89%]) included nonsustained ventricular tachycardia (VT) (n = 212 episodes [94%]), VT (n = 8 [3.5%]), and ventricular fibrillation (n = 5 [2.5%]). ATP efficacy in terminating VT was 75%. Eleven percent of episodes (n = 29) were inappropriately detected because of T-wave oversensing. Inappropriate therapy (ATP) was delivered for 14 episodes (5.5%). Three patients (10%) had worsening of tricuspid regurgitation.

CONCLUSION

Sensing from the LBBP lead for arrhythmia detection is safe as ∼90% of the episodes were detected appropriately. Future studies with a dedicated LBBP-defibrillator lead along with algorithms to avoid oversensing can help in combining defibrillation with conduction system pacing.

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.

Sex-Specific Outcomes of LBBAP Versus Biventricular Pacing: Results From I-CLAS

BACKGROUND

Cardiac resynchronization therapy (CRT) using biventricular pacing (BVP) has been associated with greater clinical improvement in women than men. Recently, left bundle branch area pacing (LBBAP) has been shown to be an alternative form of CRT.

OBJECTIVES

The purpose of this study was to investigate sex-specific outcomes for death and heart failure events in a large, international, multicenter, cohort of patients undergoing CRT with BVP or LBBAP.

METHODS

In this international study of 1,778 patients (575 female and 1203 male), sex-specific survival analysis was performed to compare the effect of LBBAP-CRT relative to BVP-CRT on the combined endpoint of death or heart failure hospitalization (HFH), and secondary endpoints of HFH only, and death alone.

RESULTS

Female patients were more likely to have nonischemic cardiomyopathy and left bundle branch block (LBBB) and less likely to have hypertension, diabetes, or coronary artery disease than were male patients. Overall, female patients had a better result with LBBAP compared with BVP than did male patients, with a significant 36% reduction in death or HFH (HR: 0.64; 95% CI: 0.43 to 0.97; P = 0.03) and a significant 60% reduction in HFH alone (HR: 0.4; 95% CI: 0.24 to 0.69, P < 0.01). Women had a greater reduction in death or HFH among those with nonischemic cardiomyopathy (HR: 0.45 95% CI: 0.26 to 0.79; P < 0.01) and LBBB (HR: 0.49; 95% CI: 0.27 to 0.87; P < 0.01). Sex-specific echocardiographic outcomes were better in women than in men.

CONCLUSIONS

Women obtained significantly greater reductions in the combined endpoint of death or HFH (primarily driven by reduction in HFH) with LBBAP compared with BVP among patients requiring CRT than did men.

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.

Pacing induced cardiomyopathy: recognition and management

Right ventricle (RV) apex continues to remain as the standard pacing site in the ventricle due to ease of implantation, procedural safety and lack of convincing evidence of better clinical outcomes from non-apical pacing sites. Electrical dyssynchrony resulting in abnormal ventricular activation and mechanical dyssynchrony resulting in abnormal ventricular contraction during RV pacing can result in adverse LV remodelling predisposing some patients for recurrent heart failure (HF) hospitalisation, atrial arrhythmias and increased mortality. While there are significant variations in the definition of pacing induced cardiomyopathy (PIC), combining both echocardiographic and clinical features, the most acceptable definition for PIC would be left ventricular ejection fraction (LVEF) of <50%, absolute decline of LVEF by ≥10% and/or new-onset HF symptoms or atrial fibrillation (AF) after pacemaker implantation. Based on the definitions used, the prevalence of PIC varies between 6% and 25% with overall pooled prevalence of 12%. While most patients undergoing RV pacing do not develop PIC, male sex, chronic kidney disease, previous myocardial infarction, pre-existing AF, baseline LVEF, native QRS duration, RV pacing burden, and paced QRS duration are the factors associated with increased risk for PIC. While conduction system pacing (CSP) using His bundle pacing and left bundle branch pacing appear to reduce the risk for PIC compared with RV pacing, both biventricular pacing and CSP may be used to effectively reverse PIC.

MAgnetic resonance imaging based DUal lead cardiac Resynchronization therapy: A prospectIve Left Bundle Branch Pacing Study (MADURAI LBBP study)

BACKGROUND

Cardiac resynchronization therapy(CRT) is a class-I indication for LVEF≤35%, and heart failure(HF). LBBB associated nonischemic-cardiomyopathy (LB-NICM) with minimal or no scar by cardiac-magnetic-resonance(CMR) imaging may be associated with excellent prognosis following CRT. Left-bundle-branch-pacing(LBBP) can achieve excellent resynchronization in LBBB patients.

OBJECTIVES

Aim of our study was to prospectively assess feasibility and efficacy of LBBP with or without a defibrillator in patients with LB-NICM and LVEF ≤35%, risk stratified by CMR.

METHODS

Pts with LB-NICM, LVEF≤35% and HF were prospectively enrolled from 2019 to 2022. If the scar burden<10% by CMR, LBBP only (Group-I) and if ≥10%, LBBP+ICD(Group-II) was performed. Primary endpoints-1.Echocardiographic-response(ER)- ΔLVEF ≥15% at 6 months; 2.Composite of time to death, HFH or sustained VT/VF. Secondary endpoints-1.Echocardiographic-hyper-response(EHR-LVEF≥50%orΔLVEF ≥20%) at 6 and 12 months; 2.Indication for ICD-upgradation(persistent LVEF<35% at 12 months or sustained VT/VF) RESULTS: 120 patients were enrolled. CMR showed <10% scar-burden in 109 patients(90.8%). 4 patients opted for LBBP+ICD and withdrew. LBBP optimized-dual-chamber-pacemaker(LOT-DDD-P) was done in 101 patients and LOT-CRT-P in 4 patients(Group-I,n=105). Scar-burden ≥10% in 11 pts who underwent LBBP+ICD(Group-II). During mean-follow-up 21±12 months, primary endpoint of ER observed in 80%(68/85 pts) in Group-I vs 27%(3/11 pts) in Group-II(p-0.0001). Primary composite-endpoint of death,HFH or VT/VF occurred in 3.8% in group-I vs 33.3% in Group-II(p<0.0001). Secondary endpoint of EHR(LVEF≥50%) observed in 39.5%vs0%, 61.2%vs9.1% and 80%vs33.3% at 3, 6 and 12 months in group-I and group-II respectively.

CONCLUSION

CMR guided CRT using LOT-DDD-P appears to be a safe and feasible approach in LB-NICM and has the potential to reduce healthcare cost.

Comparison of Left Bundle-Branch Area Pacing to Biventricular Pacing in Candidates for Resynchronization Therapy

BACKGROUND

Cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) is a well-established therapy in patients with reduced left ventricular ejection fraction (LVEF), heart failure, and wide QRS or expected frequent ventricular pacing. Left bundle branch area pacing (LBBAP) has recently been shown to be a safe alternative to BVP.

OBJECTIVE

The aim of this study was to compare the clinical outcomes between BVP and LBBAP among patients undergoing CRT.

METHODS

This observational study included patients with LVEF≤35% who underwent BVP or LBBAP for the first time for Class I or II indications for CRT between Jan 2018 to June 2022 at 15 international centers. The primary outcome was the composite endpoint of time to death or heart failure hospitalization (HFH). Secondary outcomes included endpoints of death, HFH, and echocardiographic changes. .

RESULTS

A total of 1778 patients met inclusion criteria: BVP 981, LBBAP 797. The mean age was 69±12 years, female 32%, CAD 48%, and LVEF 27±6%. Paced QRSd in LBBAP was significantly narrower than baseline (128±19 vs 161±28ms, p<0.001) and significantly narrower compared to BVP (144±23ms, p<0.001). Following CRT, LVEF improved from 27±6% to 41±13% (p<0.001) with LBBAP compared to an increase from 27±7% to 37±12% (p<0.001) with BVP with significantly greater change from baseline with LBBAP (13±12% vs 10±12%, p<0.001). On multivariable regression analysis, the primary outcome was significantly reduced with LBBAP compared BVP (20.8% vs 28%; HR 1.495; CI 1.213-1.842; p<0.001).

CONCLUSIONS

LBBAP improved clinical outcomes when compared to BVP in patients with CRT indications and may be a reasonable alternative to BVP.

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.

Left bundle branch pacing-optimized implantable cardioverter-defibrillator (LOT-ICD) for cardiac resynchronization therapy: A pilot study

Left bundle branch pacing (LBBP) involves direct capture of left bundle fibers by placing the lead deep inside the interventricular septum. Several studies have shown the feasibility and efficacy of LBBP as an alternative modality for cardiac resynchronization therapy (CRT). This paper describes approach for providing cost effective CRT with defibrillator (CRT-D) by LBBP and dual chamber implantable cardioverter defibrillator (ICD) which we label as LBBP optimized ICD (LOT-ICD). LBBP was performed using C315 sheath and 3830 Selectsecure lead in all patients by premature ventricular complex guided approach. In patients with complete correction of conduction system disease, IS-1 connector plug of the IS-1/DF-1 lead was capped and 3830 lead connected to the dual chamber ICD pulse-generator at RV-P/S port. LOT-ICD provided stable R-wave sensing for arrhythmia monitoring and resulted in cost-effective resynchronization therapy at reduced fluoroscopy duration and radiation dose.

Rescue left bundle branch area pacing in coronary venous lead failure or nonresponse to biventricular pacing: Results from International LBBAP Collaborative Study Group

BACKGROUND

Cardiac resynchronization therapy (CRT) using biventricular pacing (BVP) is effective in patients with heart failure, left bundle branch block (LBBB), and reduced left ventricular function. Left bundle branch area pacing (LBBAP) has been reported as an alternative option for CRT.

OBJECTIVE

The purpose of this study was to assess the feasibility and outcomes of LBBAP in patients who failed conventional BVP because of coronary venous (CV) lead complications or who were nonresponders to BVP.

METHODS

At 16 international centers, LBBAP was attempted in patients with conventional CRT indication who failed BVP because of CV lead complications or lack of therapeutic response to BVP. Heart failure hospitalization (HFH) and death, echocardiographic outcomes, procedural data, pacing parameters, and lead complications including CV lead failure are reported.

RESULTS

LBBAP was successfully performed in 200 patients (CV lead failures 156; nonresponders 44) (age 68 ± 11 years; female 35%; LBBB 55%; right ventricular pacing 23%; ischemic cardiomyopathy 28%; nonischemic cardiomyopathy 63%; left ventricular ejection fraction [LVEF] ≤35% in 80%). Procedural duration was 119.5 ± 59.6 minutes, and fluoroscopy duration was 25.7 ± 18.5 minutes. LBBAP threshold and R-wave amplitudes were 0.68 ± 0.35 V @ 0.45 ms and 10.4 ± 5 mV at implant, respectively, and remained stable during mean follow-up of 12 ± 10.1 months. LBBAP resulted in significant QRS narrowing from 170 ± 28 ms to 139 ± 25 ms (P <.001) with V₆ R-wave peak times of 85 ± 17 ms. LVEF improved from 29% ± 10% at baseline to 40% ± 12% (P <.001) during follow-up. The risk of death or HFH was lower in those with CV lead failure than in nonresponders (hazard ratio 0.357; 95% confidence interval 0.168-0.756; P = .007) CONCLUSION: LBBAP is a viable alternative to CRT in patients who failed conventional BVP due to CV lead failure or who were nonresponders.

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.

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.

How to Implant His Bundle and Left Bundle Pacing Leads: Tips and Pearls

Cardiac pacing is the treatment of choice for the management of patients with bradycardia. Although right ventricular apical pacing is the standard therapy, it is associated with an increased risk of pacing-induced cardiomyopathy and heart failure. Physiological pacing using His bundle pacing and left bundle branch pacing has recently evolved as the preferred alternative pacing option. Both His bundle pacing and left bundle branch pacing have also demonstrated significant efficacy in correcting left bundle branch block and achieving cardiac resynchronisation therapy. In this article, the authors review the implantation tools and techniques to perform conduction system pacing.

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.

Electrocardiography guided left bundle branch pacing

Left bundle branch pacing is a novel technique where LBB is directly captured by placing the lead deep inside the proximal septum. Electrocardiology plays a major role in identifying the target site on the right side of the septum, monitoring the lead deployment and confirming the LBB-capture. The lead is deployed 1-1.5 cm below the His bundle along an imaginary line connecting distal His signals to right ventricular apex. Rapid deployment of the lead will generate premature ventricular complexes which will guide in reaching the left bundle branch area. Several ECG based criteria will assist in confirming the conduction system capture. Further randomized trials will help in establishing the long-term safety of this novel pacing modality.

Left Posterior Fascicular Pacing

Left bundle branch pacing (LBBP) is emerging as an alternative to His bundle pacing that overcomes the latter’s limitations. Several studies have reported on the safety, efficacy, and electrophysiological properties of LBBP, while postoperative success rates range from 80.5% to 94%. The left posterior fascicle is composed of broad bands of fibers coursing inferiorly and posteriorly toward the papillary muscle, while the anterior fascicle is a thin, tendon-like structure. We report a case of a 70-year-old man in whom left posterior fascicular pacing was done after LBBP failed. We were able to demonstrate all the features of left posterior fascicular capture, including fascicular potential and a left anterior hemiblock pattern, using surface 12-lead electrocardiography. Left posterior fascicular pacing could be an alternative technique when attempts to deploy LBBP fail.

Left Bundle Branch Block-induced Cardiomyopathy: Insights From Left Bundle Branch Pacing

OBJECTIVES

The aim of the study was to report the efficacy of left bundle branch pacing (LBBP) in the management of left bundle branch block (LBBB)-induced cardiomyopathy (LIC).

BACKGROUND

Chronic LBBB is known to cause mechanical dyssynchrony and cardiomyopathy. Hyperresponse to cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) is a hallmark of LIC. LBBP has recently shown promise as an alternative to BVP.

METHODS

Patients undergoing CRT between 2018 and 2020 were retrospectively screened, and those who met the criteria for LIC were included in the study. Duration of LBBB, CRT type, and response were documented. Pacing parameters, and electrocardiographic and echocardiographic data were collected.

RESULTS

Possible LIC was identified in 17 of 159 patients undergoing CRT and LBBP was successfully performed in 13 patients. Duration of LBBB before left ventricular dysfunction was 4.2 ± 3.9 years. Temporary His bundle pacing corrected underlying LBBB in all patients. During LBBP, there was significant reduction in QRS duration (167.8 ± 11.6 ms to 110.4 ± 13.1 ms; p < 0.0001) and repolarization parameters of QTc, Tpeak-Tend, and Tpeak-Tend/QTc ratio. LBBP threshold and R waves at implant were 0.53 ± 0.21 V/0.5 ms and 11.7 ± 7.1 mV and remained stable. Cardiac magnetic resonance imaging showed no evidence of scar (n = 8). During follow-up, left ventricular ejection fraction improved from 30.4 ± 6.6% to 57.4 ± 4.7% (p < 0.0001) and New York Heart Association functional class improved from 3.1 ± 0.3 to 1.2 ± 0.4 (p < 0.0001) compared with baseline.

CONCLUSIONS

LBBP is a reasonable option for CRT in patients with LIC, as it provides low and stable capture threshold with complete correction of underlying electrical and mechanical abnormalities associated with LBBB.

Feasibility, safety and outcomes of left bundle branch pacing in octogenarians

OBJECTIVES

Left bundle branch pacing (LBBP) provides physiological pacing at low and stable threshold. The safety and efficacy of LBBP in elderly population is unknown. Our study was designed to assess the safety, efficacy and electrophysiological parameters of LBBP in octogenarian (≥80 years) population.

RESULTS

LBBP was successful in 10 out of 11 patients. Mean age 82.1 ± 2.5 yrs. Follow up duration 7.7 months(range4-10). Indication for pacing included atrioventricular (AV) block 5 patients, Left bundle branch block (LBBB) with low ejection fraction (EF) 4 patients, sinus node dysfunction in 1. QRS duration reduced from 145.9 ± 27.7ms to 107.1 ± 9.5ms (p value0.00001) LV ejection fraction increased from 47.6% to 58.4% after LBBP (p value0.017). Pacing threshold was 0.58 ± 0.22 V and sensed R wave 17.35 ± 6.5 mV and it remained stable during follow up. LBBB with low EF patients also showed similar reduction in QRS duration along with improvement in LVEF.

CONCLUSION

LBBP is a safe and effective strategy (91% acute success) of physiological pacing in elderly patients. LBBP also provided effective resynchronization therapy in our small group of elderly patients. The pacing parameters remained stable over a period of 10 months follow up.

Catheter Ablation of Pediatric Atrioventricular Nodal Re-entrant Tachycardia

Catheter ablation is considered as the standard treatment for all patients with symptomatic drug-refractory tachyarrhythmia. The safety and efficacy of the procedure in the adult population is well-established. Due to the small size of the patient and difficulty in attaining venous access, infants are rarely subjected to radiofrequency ablation. Here, we report a case of drug-refractory AV nodal re-entrant tachycardia in a two-year-old child. Radiofrequency ablation was performed with a 5-Fr sized medium-curve ablation catheter deployed at the slow pathway region where a fractionated A-wave with slow-pathway potential was recorded. After ablation, no recurrence of SVT at the end of 12 months of follow-up was observed.

Safety, Efficacy, and Intermediate-Term Outcomes of Radiofrequency Catheter Ablation for Pediatric Arrhythmias

Background

Arrhythmias are one of the reasons for emergency hospitalization among the pediatric population. Radiofrequency ablation is a major advancement in the management of children with cardiac arrhythmias.

Objectives

Our study was designed to describe the outcomes of catheter ablation in the pediatric population for atrial and ventricular arrhythmias in our center.

Methods

All patients between two and 18 years of age undergoing radiofrequency ablation after failed medical management for arrhythmias in our institute were included. Age less than two years, no previous medical management, and complex congenital heart disease were excluded. Baseline and electrophysiological characteristics were recorded. The patients were followed up for a clinical or electrocardiographic recurrence of arrhythmia.

Results

Thirty-six patients were included (mean age 12.8 ± 3.9 years (range 2-18 years), male 56%, average weight 36.39 ± 11.02 kg). The mean follow-up duration was 27.7 ± 15.9 months (range 3-58). Five-point five percent (5.5%) had tachycardiomyopathy. The arrhythmias included (1) atrioventricular nodal re-entrant tachycardia (AVNRT, n=16, 44%), (2) atrioventricular reciprocating tachycardia (AVRT, n=14, 39%), (3) atrial tachycardia (AT, n=2, 5.5%), (4) ventricular premature complexes (VPCs, n=2, 5.5%), (5) atrial flutter (AFL, n=1, 3%), and (6) ventricular tachycardia (VT, n=1, 3%). A transeptal puncture was done in 10 patients (28%). 3D mapping was done in six patients. The mean radiofrequency (RF) pulses were 2.3 ± 1.3. The acute procedural success rate was 100%. The long-term success was 97.2%. One (2.7%) developed recurrence. No major complications were reported.

Conclusion

Catheter ablation in the pediatric population is a safe procedure and can be done with more feasibility and fewer complications when done in experienced hands.

Mid-term feasibility, safety and outcomes of left bundle branch pacing-single center experience

BACKGROUND

His bundle pacing (HBP) has evolved as the most physiological form of pacing but associated with limitations. Recently, left bundle branch pacing (LBBP) is emerging as an effective alternative strategy for HBP.

OBJECTIVES

Our study was designed to assess the feasibility, efficacy, electrophysiological parameters, and mid-term outcomes of LBBP in Indian population.

METHODS

All patients requiring permanent pacemaker implantation for symptomatic bradycardia and heart failure were prospectively enrolled. Echocardiography, QRS duration, pacing parameters, left bundle (LB) potentials, paced QRS duration, and peak left ventricular activation time (pLVAT) were recorded.

RESULTS

LBBP was successful in 93 out of 99 patients (94% acute success). Mean age was 62.6 ± 13 years, male 59%, diabetes 69%, and coronary artery disease 65%. Follow-up duration was 4.8 months (range1-12 months). Indication for pacing included atrioventricular (AV) block 43%, cardiac resynchronization therapy 44%, and AV node ablation 4%. LB potential was noted in 37 patients (40%). QRS duration reduced from 144.38 ± 34.6 at baseline to 110.8 ± 12.4 ms after LBBP (p < 0.0001). Pacing threshold was 0.59 ± 0.22 V and sensed R wave 14.14 ± 7.19 mV, and it remained stable during follow-up. Lead depth in the septum was 9.62 mm. LV ejection fraction increased from 44.96 to 53.3% after LBBP (p < 0.0001). One died due to respiratory tract infection on follow up.

CONCLUSION

LBBP is a safe and effective strategy (94% acute success) of physiological pacing. The pacing parameters remained stable over a period of 12 months follow-up. LBBP can effectively overcome the limitations of HBP.

Selective left bundle branch pacing for pediatric complete heart block

Traditionally Right Ventricle has been the preferred site of pacing for the management of symptomatic brady-arrhythmias. The deleterious effect of chronic RV pacing has been shown by several studies. This has generated interest into a novel pacing strategy called physiological pacing wherein the His bundle or the left bundle is paced directly with 4.1 F pacing lead. Herewith we are reporting a case of congenital complete heart block in a 13-year-old child for whom selective left bundle branch pacing was done. This physiological pacing will ensure a synchronized contraction of the ventricles thereby avoiding the deleterious effect of RV pacing.