Background: Left bundle branch pacing (LBBP) is a novel pacing method and has been observed to have low and stable pacing thresholds in prior small short-term studies. The objective of this study w...

Long-Term Safety and Feasibility of Left Bundle Branch Pacing in a Large Single-Center Study.

Background His-bundle pacing (HBP) provides physiological ventricular activation. Observational studies have demonstrated the techniques' feasibility; however, data have come from a limited number of centers. Objectives We set out to explore the contemporary global practice in HBP focusing on the learning curve, procedural characteristics, and outcomes. Methods This is a retrospective, multicenter observational study of patients undergoing attempted HBP at seven centers. Pacing indication, fluoroscopy time, HBP thresholds, and lead reintervention and deactivation rates were recorded. Where centers had systematically recorded implant success rates from the outset, these were collated. Results A total of 529 patients underwent attempted HBP during the study period (2014-19) with a mean follow-up of 217 ± 303 days. Most implants were for bradycardia indications. In the three centers with the systematic collation of all attempts, the overall implant success rate was 81%, which improved to 87% after completion of 40 cases. All seven centers reported data on successful implants. The mean fluoroscopy time was 11.7 ± 12.0 minutes, the His-bundle capture threshold at implant was 1.4 ± 0.9 V at 0.8 ± 0.3 ms, and it was 1.3 ± 1.2 V at 0.9 ± 0.2 ms at last device check. HBP lead reintervention or deactivation (for lead displacement or rise in threshold) occurred in 7.5% of successful implants. There was evidence of a learning curve: fluoroscopy time and HBP capture threshold reduced with greater experience, plateauing after approximately 30-50 cases. Conclusion We found that it is feasible to establish a successful HBP program, using the currently available implantation tools. For physicians who are experienced at pacemaker implantation, the steepest part of the learning curve appears to be over the first 30-50 cases.

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His bundle pacing, learning curve, procedure characteristics, safety, and feasibility: Insights from a large international observational study

Abstract Aims Permanent transseptal left bundle branch area pacing (LBBAP) is a promising new pacing method for both bradyarrhythmia and heart failure indications. However, data regarding safety, feasibility and capture type are limited to relatively small, usually single centre studies. In this large multicentre international collaboration, outcomes of LBBAP were evaluated. Methods and results This is a registry-based observational study that included patients in whom LBBAP device implantation was attempted at 14 European centres, for any indication. The study comprised 2533 patients (mean age 73.9 years, female 57.6%, heart failure 27.5%). LBBAP lead implantation success rate for bradyarrhythmia and heart failure indications was 92.4% and 82.2%, respectively. The learning curve was steepest for the initial 110 cases and plateaued after 250 cases. Independent predictors of LBBAP lead implantation failure were heart failure, broad baseline QRS and left ventricular end-diastolic diameter. The predominant LBBAP capture type was left bundle fascicular capture (69.5%), followed by left ventricular septal capture (21.5%) and proximal left bundle branch capture (9%). Capture threshold (0.77 V) and sensing (10.6 mV) were stable during mean follow-up of 6.4 months. The complication rate was 11.7%. Complications specific to the ventricular transseptal route of the pacing lead occurred in 209 patients (8.3%). Conclusions LBBAP is feasible as a primary pacing technique for both bradyarrhythmia and heart failure indications. Success rate in heart failure patients and safety need to be improved. For wider use of LBBAP, randomized trials are necessary to assess clinical outcomes.

https://doi.org/10.1093/eurheartj/ehac445

Left bundle branch area pacing outcomes: the multicentre European MELOS study

Introduction Permanent deep septal stimulation with capture of the left bundle branch (LBB) enables maintenance/restoration of the physiological activation of the left ventricle. However, it is almost always accompanied by the simultaneous engagement of the local septal myocardium, resulting in a fused (nonselective) QRS complex, therefore, confirmation of LBB capture remains difficult. Methods We hypothesized that programmed extrastimulus technique can differentiate nonselective LBB capture from myocardial-only capture as the effective refractory period (ERP) of the myocardium is different from the ERP of the LBB. Consecutive patients undergoing pacemaker implantation underwent programmed stimulation delivered from the lead implanted in a deep septal position. Responses to programmed stimulation were categorized on the basis of sudden change in the QRS morphology of the extrastimuli, observed when ERP of LBB or myocardium was encroached upon, as: "myocardial," "selective LBB," or nondiagnostic (unequivocal change of QRS morphology). Results Programmed deep septal stimulation was performed 269 times in 143 patients; in every patient with the use of a basic drive train of 600 milliseconds and in 126 patients also during intrinsic rhythm. The average septal-myocardial refractory period was shorter than the LBB refractory period: 263.0 ± 34.4 vs 318.0 ± 37.4 milliseconds. Responses diagnostic for LBB capture ("myocardial" or "selective LBB") were observed in 114 (79.7%) of patients. Conclusions A novel maneuver for the confirmation of LBB capture during deep septal stimulation was developed and found to enable definitive diagnosis by visualization of both components of the paced QRS complex: selective paced LBB QRS and myocardial-only paced QRS.

Programmed deep septal stimulation: A novel maneuver for the diagnosis of left bundle branch capture during permanent pacing

Left bundle branch-optimized cardiac resynchronization therapy (LOT-CRT): results from an international LBBAP collaborative study group

Physiology-based electrocardiographic criteria for left bundle branch capture

Background During left bundle branch (LBB) area pacing, it is important to confirm that the capture of the LBB is achieved, not just the capture of only the adjacent left ventricular myocardium (LV septal capture). Our aim was to establish ECG criteria for LBB capture by analyzing ECGs with confirmed LBB capture and non-capture. We hypothesized that since LBB pacing results in physiologic depolarization of the left ventricle then the native QRS can serve as a reference for the diagnosis of LBB capture in the same patient. Methods Only patients with direct evidence of LBB capture (output-dependent or refractoriness-dependent QRS morphology transition) were included. Several QRS characteristics were compared between the native rhythm and different types of LBB area capture. Receiver-operator characteristics analysis was performed to determine the optimal V6 R-wave peak time (RWPT) cut-off for LBB diagnosis. Results A total of 357 ECG tracing (124 patients) were analyzed: 118 with native rhythm, 124 with non-selective LBB capture, 69 with selective LBB capture and 46 with LV septal capture. Our hypotheses that during LBB capture the paced V6 RWPT (measured from QRS onset) equals the native V6 RWPT and that the paced V6 RWPT (measured from the stimulus) equals the LBB potential to V6 R-wave peak interval were positively validated. Criteria based on these rules had sensitivity and specificity of 98.0–88.2% and 85.7–95.4%, respectively. The optimal and 100% specific V6 RWPT values for differentiation between LBB capture and LV septal capture in patients with narrow QRS / right bundle branch block were 83 ms and 74 ms, respectively; while in patients with left bundle branch block/asystole/ventricular escape the optimal and 100% specific V6 RWPT values were 101 ms and 80 ms, respectively. Conclusions Novel criteria for LBB capture were developed and optimal V6 RWPT cut-offs were determined. What this study adds We showed that LBB pacing truly reproduce the physiological depolarization of the left ventricle since the paced V6 RWPT equals the native conduction V6 RWPT. Individualized LBB capture criteria, that use the native QRS as a reference, were developed. The optimal V6 RWPT values for differentiation between LBB capture and LV septal capture were determined, separately for patients with healthy and diseased LBB.

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Physiology-Based Electrocardiographic Criteria for Left Bundle Branch Capture

Background: During permanent nonselective His bundle (ns-HB) pacing, it is crucial to confirm HB capture/exclude that only right ventricle (RV) myocardial septal pacing is present. Because the effe...

Programmed His Bundle Pacing: A Novel Maneuver for the Diagnosis of His Bundle Capture.

Background His-bundle (HB) pacing is the most physiological method of ventricular pacing. However, it is also considered a demanding procedure with a low success rate and has suboptimal pacing parameters. There is a scarcity of data concerning HB pacing as a standard approach in patients with symptomatic bradycardia. Our goal was to compare acute and chronic results of two approaches to pacing in patients with permanent atrial fibrillation, narrow QRS complexes, and symptomatic bradycardia: right ventricular myocardial pacing versus HB pacing. Methods Consecutive patients who received HB pacemakers were compared with historical controls-i.e., consecutive patients with classic VVI pacemaker implantations, performed by the same operator before 2014 (commencement of routine HB implantations). Acute and long-term capture threshold, sensing, battery current drain, as well as procedure and fluoroscopy duration, complications, and success rate were compared. Results One hundred and twenty-five patients were analyzed (including 65 patients with HB pacing): age 73.0 ± 10.5 years, left ventricular ejection fraction of 48.2 ± 13.5%. HB pacing was inferior to right ventricular myocardial pacing in terms of higher threshold, lower sensing amplitude, higher current drain, lower success rate, longer procedure, and fluoroscopy times. However, despite this, HB procedure and fluoroscopy times of 64.4 ± 30.0 and 11.0 ± 10.7 minutes, respectively, long-term successful HB pacing in 87.9% of patients, a chronic threshold of 1.5 ± 1.1 V, chronic sensing of 3.6 ± 2.5 mV, and chronic current drain per pulse of 3.4 ± 4.4 μAh seem acceptable. Conclusions HB pacing can be used as an alternative standard method of pacing in atrial fibrillation patients.

Agnieszka Bednarek

Papers

Physiology-based electrocardiographic criteria for left bundle branch capture

Physiology-Based Electrocardiographic Criteria for Left Bundle Branch Capture

Programmed His Bundle Pacing: A Novel Maneuver for the Diagnosis of His Bundle Capture.

His-bundle pacing as a standard approach in patients with permanent atrial fibrillation and bradycardia.

His bundle has a shorter chronaxie than does the adjacent ventricular myocardium: Implications for pacemaker programming