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.

Acute performance of stylet driven leads for left bundle branch area pacing: A comparison with lumenless leads

Background

Lumenless leads (LLLs) are widely used for left bundle branch area pacing (LBBAP). Recently, stylet-driven leads (SDLs) have also been used for LBBAP.

Objective

The purpose of this study was to evaluate the acute performance of SDLs during LBBAP in comparison with LLLs.

Methods

Consecutive patients undergoing LBBAP for bradycardia or cardiac resynchronization therapy indications at 2 high-volume, early conduction system pacing adopters, tertiary centers were included from January 2019 to July 2023. Patients received either SDLs or LLLs at the discretion of the implanting physician. Acute performance and follow-up data of both lead types were evaluated.

Results

A total of 925 LBBAP implants were included, 655 using LLLs and 270 using SDLs. Overall, LBBAP acute success was significantly higher with LLLs than SDLs (95.3% vs 85.1%, respectively; P <.001) even after the learning curve (97% vs 86%; P = .013). LLLs were implanted in more mid-basal septal positions in comparison with SDLs, which tended to be implanted in more inferior and mid-apical septal positions. Acute lead-related complications were higher with SDLs than LLLs (15.9% vs 6.1%, respectively; P <.001) with 15 cases of lead damage during implant (4.4% vs 0.5%; P <.001) but decreased with acquired experience and were comparable in the last 100 patients included in each group. Lead implant and fluoroscopy times were shorter for SDLs, with lead dislodgment occurring in 0.9% with LLLs and 1.5% with SDLs (P = .489).

Conclusion

Acute lead performance proved to be different between LLLs and SDLs. A specific learning curve should be considered for SDLs even for implanters with extensive previous experience with LLLs.

His-Purkinje Conduction System Pacing Optimized Trial of Cardiac Resynchronization Therapy vs Biventricular Pacing: HOT-CRT Clinical Trial

BACKGROUND

His-Purkinje conduction system pacing (HPCSP) using His bundle pacing (HBP) or left bundle branch pacing (LBBP) has emerged as an alternative to biventricular pacing (BVP) in patients requiring cardiac resynchronization therapy (CRT).

OBJECTIVES

The aim of the study was to compare the feasibility and clinical efficacy of HOT-CRT (His-Purkinje conduction system pacing Optimized Trial of Cardiac Resynchronization Therapy) with BVP in patients with heart failure, reduced ejection fraction, and indication for CRT.

METHODS

This was a prospective, randomized, controlled trial of HOT-CRT and BVP in patients with LVEF <50% and indications for CRT. If HPCSP resulted in incomplete electrical resynchronization, a coronary sinus (CS) lead was added. The primary outcome was the change in left ventricular ejection fraction (LVEF) at 6 months. The primary safety endpoint was freedom from major complications.

RESULTS

A total of 100 patients (female 31%, aged 70 ± 12 years, LVEF 31.5% ± 9.0%) were randomized. HOT-CRT was successful in 48 of 50 (96%) and BVP-CRT in 41 of 50 (82%) patients (P = 0.03). QRS duration significantly decreased from 164 ± 26 ms to 137 ± 20 ms with HOT-CRT and 166 ± 28 ms to 141 ± 19 ms with BVP. Fluoroscopy results (18.8 ± 12.4 min vs 23.8 ± 12.4 min, P = 0.05) and procedure duration (119 ± 42 min vs 114 ± 36 min, P = 0.5) were similar. The primary outcome of change in LVEF at 6 months was greater in HOT-CRT than in BVP (12.4% ± 7.3% vs 8.0% ± 10.1%, P = 0.02). The primary safety endpoint was similar (98% vs 94%, P = 0.62). Echocardiographic response of improvement in LVEF >5% occurred in 80% vs 61% (P = 0.06). Complications occurred in 3 (6%) in HOT-CRT vs 10 (20%) in BVP (P = 0.03).

CONCLUSIONS

HPCSP-guided CRT resulted in greater change in LVEF compared with BVP. Randomized clinical trials with long-term follow-up are necessary. (His-Purkinje Conduction System Pacing Optimized Trial of Cardiac Resynchronization Therapy [HOT-CRT]; NCT04561778).

Giant Interventricular Septal Hematoma Complicating Left Bundle Branch Pacing: A Cautionary Tale

An 88-year-old woman underwent atrioventricular node ablation and left bundle branch pacing for atrial fibrillation. She presented to the emergency room several hours after discharge with dyspnea. An echocardiogram revealed a giant interventricular septal hematoma. The patient was successfully treated with conservative medical therapy, with eventual complete resolution of the hematoma. (Level of Difficulty: Intermediate.).

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.

Clinical outcomes of conduction system pacing compared to biventricular pacing in patients requiring cardiac resynchronization therapy

BACKGROUND

Cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) is well-established therapy in patients with reduced left ventricular ejection fraction (LVEF) and bundle branch block or indication for pacing. Conduction system pacing (CSP) using His-bundle pacing (HBP) or left bundle branch area pacing (LBBAP) has been shown to be a safe and more physiological alternative to BVP.

OBJECTIVE

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

METHODS

This observational study included consecutive patients with LVEF ≤35% and class I or II indications for CRT who underwent successful BVP or CSP at 2 major health care systems. The primary outcome was the composite endpoint of time to death or heart failure hospitalization (HFH). Secondary outcomes included subgroup analysis in left bundle branch block as well as individual endpoints of death and HFH.

RESULTS

A total of 477 patients (32% female) met inclusion criteria (BVP 219; CSP 258 [HBP 87, LBBAP 171]). Mean age was 72 ± 12 years, and mean LVEF was 26% ± 6%. Comorbidities included hypertension 70%, diabetes mellitus 45%, and coronary artery disease 52%. Paced QRS duration in CSP was significantly narrower than BVP (133 ± 21 ms vs 153 ± 24 ms; P <.001). LVEF improved in both groups during mean follow-up of 27 ± 12 months and was greater after CSP compared to BVP (39.7% ± 13% vs 33.1% ± 12%; P <.001). Primary outcome of death or HFH was significantly lower with CSP vs BVP (28.3% vs 38.4%; hazard ratio 1.52; 95% confidence interval 1.082-2.087; P = .013).

CONCLUSION

CSP improved clinical outcomes compared to BVP in this large cohort of patients with indications for CRT.

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.

Conduction System Pacing versus Conventional Pacing in Patients Undergoing Atrioventricular Node Ablation: Non-randomized, On-Treatment Comparison

Background

Atrioventricular node ablation (AVNA) with right ventricular or biventricular pacing (conventional pacing; CP) is an effective therapy for patients with refractory atrial fibrillation (AF). Conduction system pacing (CSP) using His bundle pacing or left bundle branch area pacing preserves ventricular synchrony.

Objective

The aim of our study is to compare the clinical outcomes between CP and CSP in patients undergoing AVNA.

Methods

Patients undergoing AVNA at Geisinger Health System between January 2015 and October 2020 were included in this retrospective observational study. CP or CSP was performed at the operators’ discretion. Procedural, pacing parameters, and echocardiographic data were assessed. Primary outcome was the combined endpoint of time to death or heart failure hospitalization (HFH) and was analyzed using Cox proportional hazards. Secondary outcomes were individual outcomes of time to death and HFH.

Results

AVNA was performed in 223 patients (CSP, 110; CP, 113). Age was 75 ± 10 years, male 52%, hypertension 67%, diabetes 25%, coronary disease 40%, and left ventricular ejection fraction (LVEF) 43% ± 15%. QRS duration increased from 103 ± 30 ms to 124 ± 20 ms (P < .01) in CSP and 119 ± 32 ms to 162 ± 24 ms in CP (P < .001). During a mean follow-up of 27 ± 19 months, LVEF significantly increased from 46.5% ± 14.2% to 51.9% ± 11.2% (P = .02) in CSP and 36.4% ± 16.1% to 39.5% ± 16% (P = .04) in CP. The primary combined endpoint of time to death or HFH was significantly reduced in CSP compared to CP (48% vs 62%; hazard ratio 0.61, 95% confidence interval 0.42–0.89, P < .01). There was no reduction in the individual secondary outcomes of time to death and HFH in the CSP group compared to CP.

Conclusion

CSP is a safe and effective option for pacing in patients with AF undergoing AVNA in high-volume centers.

Clinical Outcomes Of Left Bundle Branch Area Pacing Compared To His Bundle Pacing

BACKGROUND

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.

OBJECTIVE

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 to 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=0.643). There were no statistically significant differences in the primary composite outcome in LBBAP (17.3%) compared to HBP (24.5%) (HR 1.15, CI 0.72-1.82, p = 0.552). Secondary outcomes of death (10 vs 17%; HR 1.3, CI 0.73-2.33, p=0.38) and HFH (10 vs 12%; HR 1.02,CI 0.54-1.94, p=0.94) 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. This article is protected by copyright. All rights reserved.

Clinical outcomes of left bundle branch area pacing compared to right ventricular pacing: Results from the Geisinger-Rush Conduction System Pacing Registry

BACKGROUND

Left bundle branch area pacing (LBBAP) has been shown to be a feasible option for patients requiring ventricular pacing.

OBJECTIVE

The purpose of this study was to compare clinical outcomes between LBBAP and RVP among patients undergoing pacemaker implantation METHODS: This observational registry included patients who underwent pacemaker implantations with LBBAP or RVP for bradycardia indications between April 2018 and October 2020. The primary composite outcome included all-cause mortality, heart failure hospitalization (HFH), or upgrade to biventricular pacing. Secondary outcomes included the composite endpoint among patients with a prespecified burden of ventricular pacing and individual outcomes.

RESULTS

A total of 703 patients met inclusion criteria (321 LBBAP and 382 RVP). QRS duration during LBBAP was similar to baseline (121 ± 23 ms vs 117 ± 30 ms; P = .302) and was narrower compared to RVP (121 ± 23 ms vs 156 ± 27 ms; P <.001). The primary composite outcome was significantly lower with LBBAP (10.0%) compared to RVP (23.3%) (hazard ratio [HR] 0.46; 95%T confidence interval [CI] 0.306-0.695; P <.001). Among patients with ventricular pacing burden >20%, LBBAP was associated with significant reduction in the primary outcome compared to RVP (8.4% vs 26.1%; HR 0.32; 95% CI 0.187-0.540; P <.001). LBBAP was also associated with significant reduction in mortality (7.8% vs 15%; HR 0.59; P = .03) and HFH (3.7% vs 10.5%; HR 0.38; P = .004).

CONCLUSION

LBBAP resulted in improved clinical outcomes compared to RVP. Higher burden of ventricular pacing (>20%) was the primary driver of these outcome differences.

His bundle pacing capture threshold stability during long-term follow-up and correlation with lead slack

AIMS

His bundle pacing (HBP) is the most physiologic form of pacing. Long-term HBP capture threshold stability and its relation to lead characteristics at the time of implantation have not been adequately described. The aim of this study was to characterize HB capture threshold in follow-up and to identify potential lead characteristics predictive of lead capture instability.

METHODS AND RESULTS

Consecutive patients with successful HBP for bradycardia indications were identified from the Geisinger HBP registry. His bundle capture thresholds, baseline comorbidities, and radiographic lead slack characteristics were analysed. An increase in HB capture threshold ≥1 V above implant values at any time during follow-up was tracked. Forty-four of the 294 studied (15%) experienced HB capture threshold increase by ≥ 1 V. Threshold increase was seen early (41% by 8 weeks, 66% by 1 year). Eighteen (6%) patients required lead revision in follow-up. Abnormal slack shape was associated with a trend toward capture threshold increase [hazard ratio (HR) 2.07; 95% confidence interval (CI) 0.9-4.6; P = 0.08]. Non-perpendicular angle of lead insertion on radiography was associated with the capture threshold increase (HR 2.81, 95% CI 1.4-5.8; P < 0.01).

CONCLUSION

His bundle capture threshold remains stable in the majority (85%) of patients. Implant characteristics may predict the threshold rise. Further evaluation of the aetiology of threshold increase and design changes in lead and delivery systems may lead to chronically stable capture thresholds.

His-Purkinje Conduction System Pacing in Atrioventricular Block: New Insights into Site of Conduction Block

OBJECTIVES

This study aims to assess the safety and feasibility of achieving His-Purkinje conduction system pacing (HPCSP) in consecutive patients with atrioventricular block (AVB) and to describe the site of conduction block in patients with infranodal AVB.

BACKGROUND

HPCSP has evolved as the preferred form of physiologic pacing. Left bundle branch area pacing (LBBAP) has emerged as an effective alternative to His bundle pacing (HBP).

METHODS

Consecutive patients with AVB referred for pacemaker implantation were included in the study. HBP or LBBAP was attempted in all patients. Site of conduction block was identified as nodal or infranodal (intra-Hisian or infra-Hisian) AVB.

RESULTS

HPCSP was attempted in 333 consecutive patients with AVB and was successful in 322 (97%) patients. HBP was achieved in 140 patients, LBBAP in 179 patients, and both in 3 patients. Site of conduction block was nodal in 55% and infranodal in 45% (intra-Hisian 89%; infra-Hisian 4%; indeterminate 7%). QRS duration at baseline was 111±27 versus 129±31 (P < 0.001) compared to 126 ± 24 vs 125 ± 21 milliseconds (P = 0.75) during HBP and LBBAP, respectively. HBP thresholds at implant were higher compared to LBBAP (1.2 ± 0.7 V at 0.9 milliseconds vs 0.6 ± 0.3 V at 0.5 milliseconds; P < 0.001) but remained stable during follow-up. Lead revision was required in 3% and 2% of patients with HBP and LBBAP, respectively.

CONCLUSIONS

HPCSP pacing was successfully performed in 97% of unselected patients with AVB irrespective of the site of conduction block. True infra-Hisian block (distal His-Purkinje conduction disease) is rare. HBP and LBBAP were complementary in achieving stable and low capture thresholds.

Cardiac troponin release following left bundle branch pacing

Left bundle branch pacing (LBBP) has emerged as an alternative to His bundle pacing (HBP) to achieve physiologic ventricular stimulation. The extent of myocardial injury during permanent LBBP implantation is currently not known. The aim of the study was to prospectively assess the extent of myocardial injury during LBBP implantation. Cardiac troponin (cTn) levels were measured at baseline and 6-12 h following permanent LBBP. The number of attempts to achieve LBBP was documented. Troponin levels were measured in a control population undergoing other electrophysiology procedures including HBP, other devices involving right ventricular (RV) pacing, radiofrequency ablation for atrial fibrillation (AF) and supraventricular tachycardia (SVT). Significant elevation of troponin (SET) was defined as threefold increase above the upper reference limit (URL) for cTn. Between December 2019 and April 2020, 204 were prospectively enrolled: LBBP in 98 and Control group 106 (SVT, 55; AF, 20; HBP, 17; other devices, 14). SET (>3× URL) was seen in 49.4% of patients in the LBBP group compared to 58.4% in the control group (p = .23). Peak troponin levels were greater in the control group compared to the LBBP group (230.3 ± 320.1 vs. 87.4 ± 71.3 pg/ml; p = .0001). Compared to LBBP (49.4%), SET was observed less frequently following HBP (17.5%; p = .01), and other device implantation (29%; p = .15). Patients requiring >2 attempts (n = 33) had significantly higher incidence of SET compared to <2 attempts (n = 56; 66.7% vs. 39.3%; p = .01). LBBP implantation is associated with myocardial injury. Asymptomatic troponin release following LBBP is less than or comparable to other interventional electrophysiology procedures.

Imaging-Based Localization of His Bundle Pacing Electrodes: Results From the Prospective IMAGE-HBP Study

OBJECTIVES

This study sought to evaluate the correlation between His bundle (HB) pacing (HBP) implantation characteristics, lead-tip location, and association of intraprocedural His recordings with approximated HB anatomic landmarks using computed tomography (CT) imaging.

BACKGROUND

HBP continues to grow in clinical practice due to offering true physiological pacing. However, a clear understanding of HB anatomy and the lead-tip location's influence on pacing characteristics is lacking.

METHODS

The IMAGE-HBP study (Imaging Study of Lead Implant for His Bundle Pacing) was a prospective, multicenter study designed to assess implantation characteristics of the SelectSecure Model 3830 lead placed at the HB, evaluate protocol-specified HBP success (His recording present on electrogram and HBP threshold ≤2.5 V at 1 ms), and correlation between lead-tip location by CT imaging and HBP characteristics as well as lead-related complications through 12 months.

RESULTS

Sixty-nine patients underwent a lead implantation attempt at the HB. Of these, 61 patients (88%) had a lead successfully implanted at the HB, and 52 patients (75%) met the pre-specified definition of successful HBP. In 51 patients with CT imaging, 11 leads (22%) were placed in the atrial aspect of the HB region (36% selective HBP), and 40 leads (78%) were placed in the ventricular aspect (28% selective HBP). Four of the 51 patients had P-wave oversensing, all with leads in the atrium. Freedom from lead-related complication at 12 months was 93%.

CONCLUSIONS

Successful HBP could be achieved at lead-tip locations in the atrium or ventricle but is preferable in the ventricle to eliminate risk of oversensing. The IMAGE-HBP study offers better insight into approximated HB anatomic landmarks, lead-tip location, and correlation with pacing characteristics. (Imaging Study of Lead Implant for His Bundle Pacing [IMAGE-HBP]; NCT03294317).

Clinical Outcomes of Selective Versus Nonselective His Bundle Pacing

OBJECTIVES

The aim of the study was to evaluate the clinical outcomes of nonselective (NS) His bundle pacing (HBP) compared with selective (S) HBP.

BACKGROUND

HBP is the most physiologic form of ventricular pacing. NS-HBP results in right ventricular septal pre-excitation due to fusion with myocardial capture in addition to His bundle capture resulting in widened QRS duration compared with S-HBP wherein there is exclusive His bundle capture and conduction.

METHODS

The Geisinger and Rush University HBP registries comprise 640 patients who underwent successful HBP. Our study population included 350 consecutive patients treated with HBP for bradyarrhythmic indications who demonstrated ≥20% ventricular pacing burden 3 months post-implantation. Patients were categorized into S-HBP or NS-HBP based on QRS morphology (NS-HBP n = 232; S-HBP n = 118) at the programmed output at the 3-month follow-up. The primary analysis outcome was a combined endpoint of all-cause mortality or heart failure hospitalization.

RESULTS

The NS-HBP group had a higher number of men (64% vs. 50%; p = 0.01), higher incidence of infranodal atrioventricular block (40% vs. 9%; p < 0.01), ischemic cardiomyopathy (24% vs. 14%; p = 0.03), and permanent atrial fibrillation (18% vs. 8%; p = 0.01). The primary endpoint occurred in 81 of 232 patients (35%) in the NS-HBP group compared with 23 of 118 patients (19%) in the S-HBP group (hazard ratio: 1.38; 95% confidence interval: 0.87 to 2.20; p = 0.17). Subgroup analyses of patients at greatest risk (higher pacing burden or lower left ventricular ejection fraction) revealed no incremental risk with NS-HBP.

CONCLUSIONS

NS-HBP was associated with similar outcomes of death or heart failure hospitalization when compared with S-HBP. Multicenter risk-matched clinical studies are needed to confirm these findings.

Long-Term Results of His Bundle Pacing

Right ventricular pacing is associated with pacing-induced cardiomyopathy in some patients. His Bundle Pacing (HBP) is an alternative site to pace to achieve ventricular contraction with fewer adverse hemodynamic effects. HBP has been shown to be safe and feasible in the short term. The few studies that look at long-term results of HBP are promising with regard to electrophysiological, echocardiographic, and clinical outcomes. Further randomized clinical trials are needed to fully understand the long-term effects of HBP.

Atrioventricular node ablation and His bundle pacing

Aims

Atrioventricular node ablation (AVNA) and right ventricular pacing (RVP) are effective therapies for patients with atrial fibrillation (AF) and rapid ventricular rates. His bundle pacing (HBP) is a physiologic alternative to RVP. The aim of our study is to assess the feasibility and safety of HBP in patients undergoing AVNA and its effect on left ventricular (LV) function.

Methods and results

Permanent HBP is the preferred form of ventricular pacing at our institute. Atrioventricular node ablation and HBP were performed in patients with AF and difficulty in rate control. His bundle pacing implant characteristics and thresholds were recorded. Fluoroscopic relationship of AVNA site to HBP lead electrodes was documented. Left ventricular ejection fraction (LVEF) and New York Heart Association (NYHA) functional class at baseline and during follow-up were assessed. Forty-two patients underwent HBP and AVNA: age 74 ± 11 years; men 45%; HTN 64%; DM 19%; CAD 36%; permanent AF 40%; cardiomyopathy 55%. His bundle pacing was successful in 40 of 42 patients (95%). Successful AVNA site was at or below the ring electrode in 22 (no acute change in HBP threshold); above the ring electrode in 13 and left side in 2 pts (acute increase in HBP threshold in 7 of 15 pts). Final HBP threshold at implant was 1 ± 0.8 V@1 ms and increased to 1.6 ± 1.2 V@1 ms during a mean follow-up of 19 ± 14 months. Left ventricular ejection fraction increased from 43 ± 13% to 50 ± 11% (P = 0.01). New York Heart Association functional status improved from 2.5 ± 0.5 to 1.9 ± 0.5 (P = 0.04).

Conclusion

Atrioventricular node ablation and HBP were successful in 95% of patients. His bundle pacing lead characteristics remained relatively stable. Left ventricular ejection fraction improved significantly during follow-up. His bundle pacing is feasible, safe and effective in pts undergoing AVNA.

Permanent His-bundle pacing in patients with prosthetic cardiac valves

BACKGROUND

Conduction disease is not uncommon after prosthetic valve (PV) surgery. The feasibility of His-bundle pacing (HBP) in this patient population is not well studied.

OBJECTIVE

The purpose of this study was to report our experience with permanent HBP in patients undergoing pacemaker implantation after PV surgery.

METHODS

Permanent HBP was attempted in patients with AV conduction disease after PV surgery referred for pacemaker implantation. Conduction disease was characterized as AV nodal vs infranodal. Feasibility, relationship of HBP lead to PVs, and HBP characteristics were recorded.

RESULTS

Thirty patients (47% men, age 74 ± 12 years, left ventricular ejection fraction 49% ± 11%) with AV conduction disease (100% patients; 14 with infranodal block; right bundle branch block 9, left bundle branch block 5, intraventricular conduction delay 1) underwent HBP. PVs included aortic valve replacement (AVR) in 8 patients (infranodal block 6 patients), tricuspid valve (TV) ring with mitral valve replacement or repair (MVR) in 10 patients (AV nodal block 9 patients), transcatheter aortic valve replacement (TAVR) in 4 patients (infranodal block 4 patients), and MVR alone in 6 patients. HBP was successful in 28 patients (93%) (selective HBP 50%). His bundle (HB) recruitment was unsuccessful in 2 patients with TAVR. AVR/TAVR and TV ring served as anatomic landmarks for localizing the HB. Successful sites of HBP were posterior and inferior to AVR/TAVR and distal and septal to the TV ring. Baseline QRSd improved from 124 ± 32 ms to 118 ± 20 ms (P = .39). HBP threshold at implant was 1.45 ± 1 V at 1 ms.

CONCLUSION

Permanent HBP was feasible in 93% of patients with PVs. Patients with AVR/TAVR predominantly developed infranodal block compared to AV nodal block in patients with TV ring/MVR. Location of PV might serve as a landmark for identifying the site of the HB.