His-Purkinje Conduction System Pacing Research Articles

Review of Atrioventricular Node Ablation Combined with Permanent His-Purkinje Conduction System Pacing in Patients with Atrial Fibrillation with Heart Failure.

With the advancement of pacing technologies, His-Purkinje conduction system pacing (HPCSP) has been increasingly recognized as superior to conventional right ventricular pacing (RVP) and biventricular pacing (BVP). This method is characterized by a series of strategies that either strengthen the native cardiac conduction system or fully preserve physical atrioventricular activation, ensuring optimal clinical outcomes. Treatment with HPCSP is divided into two pacing categories, His bundle pacing (HBP) and left bundle branch pacing (LBBP), and when combined with atrioventricular node ablation (AVNA), can significantly improve left ventricular (LV) function. It effectively prevents tachycardia and regulates ventricular rates, demonstrating its efficacy and safety across different QRS wave complex durations. Therefore, HPCSP combined with AVNA can alleviate symptoms and improve the quality of life in patients with persistent atrial fibrillation (AF) who are unresponsive to multiple radiofrequency ablation, particularly those with concomitant heart failure (HF) who are at risk of further deterioration. As a result, this "pace and ablate" strategy could become a first-line treatment for refractory AF. As a pacing modality, HBP faces challenges in achieving precise localization and tends to increase the pacing threshold. Thus, LBBP has emerged as a novel approach within HPCSP, offering lower thresholds, higher sensing amplitudes, and improved success rates, potentially making it a preferable alternative to HBP. Future large-scale, prospective, and randomized controlled studies are needed to evaluate patient selection and implantation technology, aiming to clarify the differential clinical outcomes between pacing modalities.

Feasibility and safety of physiologic pacing post-TAVR

Abstract Introduction His-Purkinje conduction system pacing (HPCSP) is an increasingly used technique due to its benefits. The transcatheter aortic valve replacement (TAVR) has in turn been growing and surpasses the number of procedures than surgical aortic valve replacement, however, the main disadvantage with respect to the surgical technique is a greater risk of atrioventricular block and the need for permanent pacing. Purpose Assess the feasibility of HPCSP in patients after TAVR, the success rates and the pacing thresholds. Methods We present a series of consecutive patients (undergoing TAVI in a single center with need for subsequent ventricular stimulation (n=58), from March 2019 to July 2023, performing HPCSP as the first stimulation option. Results We achieved HPCSP in 49 of 58 patients (84.5%). Patients had a mean age of 81.5 years, 60.3% men, mean LVEF 53.82 ± 12.4%. His bundle pacing (HBP) was successful as first option in 41.4% of cases, and left bundle branch area (LBBAP) in 43,1 % of cases (73.5% of the remaining 58.6%) , while the other 9 patients (15.5%) were pace conventionally at right ventricle, septal or wireless. HBP thresholds and R-wave amplitudes at implantation were 0.99 ± 0.72 at 0.5 ms, 4.59 ± 3.67 mV), remaining stable at follow-up at 1 month (1.16 ± 0.92 at 0.5 ms, 4.17 ± 3.97 mV),. Average QRS width was40.8 ± 21.3 ms pre and 122.43 ± 15.2 ms post). LBBAP pacing thresholds and R-wave amplitudes were(0.89 ± 0.45 at 0.5 ms, 6.145 ± 5.3 mV)at implant, and were stable at follow-up at 1 month (0.75 ± 0.3 at 0.5 ms, 8.41 ± 5.8 mV), with no improvements on QRS (129.75 ± 21.01 ms pre, 134.13 ± 17.34 ms post). During a mean follow-up of 23 months. There has been no acute elevation of thresholds or need for reintervention. Only 6 patients have died (10.3%), 2 of them (33%) from cardiovascular causes. Conclusions HPCSP is feasible as a routine techniquein patients after TAVR who need a pacemaker implantation, with low pacing thresholds, which remained stable on the follow-up.

Animal study on left bundle branch current of injury and anatomic location of leads in His-purkinje conduction system pacing

Objective: Explore the relationship between tip of the left bundle branch pacing lead and anatomic location of left bundle branch as well as the mechanism of left bundle branch current of injury. To clarify the clinical value of left bundle branch current of injury during operation. Methods: The pacing leads were implanted in the hearts of two living swines. Intraoperative electrophysiological study confirmed that the left bundle branch or only the deep left ventricular septum was captured at low output. Immediately after operation, the gross specimen of swine hearts was stained with iodine to observe the gross distribution of His-purkinje conduction system on the left ventricular endocardium and its relationship with the leads. Subsequently, the swine hearts were fixed with formalin solution, and the pacing leads were removed after the positions were marked. The swine hearts were then sectioned and stained with Masson and Goldner trichrome, and the relationship between the anatomic location of the conduction system and the tip of the lead was observed under a light microscope. Results: After iodine staining of the specimen, the His-purkinje conduction system was observed with the naked eye in a net-like distribution, and the lead tip was screwed deeply and fixed in the left bundle branch area of the left ventricular subendocardium in the ventricular septum. Masson and Goldner trichrome staining showed that left bundle branch pacing lead directly passed through the left bundle branch when there was left bundle branch potential with left bundle branch current of injury, while it was not directly contact the left bundle branch when there was left bundle branch potential without left bundle branch current of injury. Conclusion: The left bundle branch current of injury observed on intracardiac electrocardiogram during His-purkinje conduction system pacing suggests that the pacing lead directly contacted the conduction bundle or its branches, therefore, the captured threshold was relatively low. Left bundle branch current of injury can be used as an important anatomic and electrophysiological evidence of left bundle branch capture.

ECG characteristics of “true” left bundle branch block: Insights from transcatheter aortic valve–related LBBB and His-Purkinje conduction system pacing–correctable LBBB

Left bundle branch block (LBBB) pattern on the electrocardiogram includes patients with both complete conduction block in the His-Purkinje system as well as nonspecific left ventricular conduction delay without discrete block. The purpose of this study was to characterize electrocardiographic morphological features of LBBB patterns in patients with (1) LBBB after transcatheter aortic valve replacement (TAVR) and (2) LBBB correctable by conduction system pacing (CSP). Consecutive patients with post-TAVR (n = 123) or CSP-correctable LBBB (n = 58) from 2 centers were included in this retrospective evaluation. QRS durations as well as detailed morphological features, including notching and slurring, of QRS complexes in leads I, aVL, V1, V2, V5, and V6 and in all 3 inferior leads were recorded. The mean age of the entire cohort was 78.3 ± 10.1 years, with 48% of the cohort being male(87/181). In the CSP-correctable group (n = 58), 14 (24.1%) underwent His-bundle pacing and 44 (75.9%) left bundle branch area pacing. A total of 17 of 181 (9.4%) of the combined cohort failed to completely meet the Strauss criteria. QRS morphology in lead V1/V2 was always either rS or QS, and there were no q/Q waves noted in lead V5/V6. Although dominant R waves were seen in leads I and aVL of 176 of 181 (97.2%), q/Q waves were present in only 21 of 181 (11.6%). Importantly, notched or slurred QRS complexes were identified in at least 1 lead of 4 leads I, aVL, V5, and V6 in 181 of 181 (100%). Strauss criteria and QRS notching are highly prevalent in LBBB after TAVR and in LBBB correctable by CSP.

Cardiac resynchronization therapy for patients with heart failure and nonspecific intraventricular conduction delay.

The efficacy of cardiac resynchronization therapy (CRT) in heart failure patients with left bundle branch block (LBBB) is well established with Class I or IIa recommendation according to 2021 ESC Guidelines on cardiac pacing and CRT, whereas non-LBBB morphology is less recommended. There is insufficient evidence that proves patients with NICD could benefit from CRT. As patients with NICD are characterized by heterogeneity, the effect of CRT on these patients is still controversial. Although the proportion of NICD in the population is lower than that of LBBB patients, it is still worth investigating the effects of CRT on patients with NICD in an era of His-Purkinje conduction system pacing (HPCSP).

The feasibility and safety of his-purkinje conduction system pacing in patients with heart failure with severely reduced ejection fraction.

The purpose of this study was to evaluate the feasibility and outcomes of conduction system pacing (CSP) in patients with heart failure (HF) who had a severely reduced left ventricular ejection fraction (LVEF) of less than 30% (HFsrEF). Between January 2018 and December 2020, all consecutive HF patients with LVEF < 30% who underwent CSP at our center were evaluated. Clinical outcomes and echocardiographic data [LVEF and left ventricular end-systolic volume (LVESV)], and complications were all recorded. In addition, clinical and echocardiographic (≥5% improvement in LVEF or ≥15% decrease in LVESV) responses were assessed. The patients were classified into a complete left bundle branch block (CLBBB) morphology group and a non-CLBBB morphology group according to the baseline QRS configuration. Seventy patients (66 ± 8.84 years; 55.7% male) with a mean LVEF of 23.2 ± 3.23%, LVEDd of 67.33 ± 7.47 mm and LVESV of 212.08 ± 39.74 ml were included. QRS configuration at baseline was CLBBB in 67.1% (47/70) of patients and non-CLBBB in 32.9%. At implantation, the CSP threshold was 0.6 ± 0.3 V @ 0.4 ms and remained stable during a mean follow-up of 23.43 ± 11.44 months. CSP resulted in significant LVEF improvement from 23.2 ± 3.23% to 34.93 ± 10.34% (P < 0.001) and significant QRS narrowing from 154.99 ± 34.42 to 130.81 ± 25.18 ms (P < 0.001). Clinical and echocardiographic responses were observed in 91.4% (64/70) and 77.1% (54/70) of patients. Super-response to CSP (≥15% improvement in LVEF or ≥30% decrease in LVESV) was observed in 52.9% (37/70) of patients. One patient died due to acute HF and following severe metabolic disorders. Baseline BNP (odds ratio: 0.969; 95% confidence interval: 0.939-0.989; P = 0.045) was associated with echocardiographic response. The proportions of clinical and echocardiographic responses in the CLBBB group were higher than those in the non-CLBBB group but without significant statistical differences. CSP is feasible and safe in patients with HFsrEF. CSP is associated with a significant improvement in clinical and echocardiographic outcomes, even for patients with non-CLBBB widened QRS.

His-Purkinje conduction system pacing combined with atrioventricular node ablation improves quality of life in older patients with persistent atrial fibrillation refractory to multiple ablation procedures.

Recurrence of atrial fibrillation (AF) is common in patients with persistent AF even after multiple ablation procedures. His-Purkinje conduction system pacing (HPCSP) combined with atrioventricular node ablation (AVNA) is effective in managing patients with AF and heart failure. This study aimed to determine whether HPCSP combined with AVNA can improve quality of life and alleviate symptoms in older patients with symptomatic persistent AF refractory to multiple ablation procedures, as well as evaluate the feasibility and safety of this therapy. Older patients (≥ 65 years) with symptomatic persistent AF refractory to at least two ablation procedures were treated with combined HPCSP and AVNA. The success rates and complications were recorded. Pacing parameters, European Heart Rhythm Association (EHRA) scores, and Atrial Fibrillation Effect on Quality-of-Life (AFEQT) scores obtained perioperatively were compared with those recorded at the 6-month follow-up examination. Thirty-one patients were enrolled; of those, only thirty patients were eventually treated with AVNA because one patient developed a complete atrioventricular block following the withdrawal of the His bundle pacing lead. The success rates were 100% for HPCSP (22 cases with His bundle pacing, and 9 cases with left bundle branch pacing) and 93.3% (28/30) for AVNA, respectively. By the 6-month follow-up examination, EHRA scores improved significantly (3.00 ± 0.73 vs. 2.44 ± 0.63, P = 0.014) and AFEQT scores increased markedly (49.6 ± 20.6 vs. 70.9 ± 14.0, P = 0.001). No severe complications developed. When used in older patients with symptomatic persistent AF refractory to multiple ablation procedures, HPCSP combined with AVNA significantly alleviated symptoms and improved quality of life during short-term follow-up. This therapy was proved to be safe and effective in this patient population.

His-Purkinje conduction system pacing and atrioventricular node ablation in treatment of persistent atrial fibrillation refractory to multiple ablation procedures: A case report

In patients with symptomatic atrial fibrillation refractory to optimal medical therapy, atrioventricular node ablation followed by permanent pacemaker implantation is an effective treatment option. A 66-year-old woman with symptomatic persistent atrial fibrillation refractory to multiple ablation procedures was referred to our institution. After optimal drug therapy, the patient still had obvious symptoms. Sequential His-Purkinje conduction system pacing and atrioventricular node ablation were performed. Left bundle branch pacing was used as a backup pacing method if thresholds of His bundle pacing were too high or loss of His bundle capture occurred in the follow-up. At the 6-month follow-up, the European Heart Rhythm Association classification for AF was improved, the score of the Atrial Fibrillation Effect on Quality of Life was enhanced, and the 6-Minute Walk Test was ameliorated. The present case was subjected to His-Purkinje conduction system pacing in combination with atrioventricular node ablation as treatment for a symptomatic persistent atrial fibrillation refractory to multiple ablation procedures, and this procedure alleviated symptoms and improved the quality of life in a short-term follow-up.

Recruitment of the cardiac conduction system for optimal resynchronization therapy in failing heart.

Heart failure (HF) is a leading health burden around the world. Although pharmacological development has dramatically advanced medication therapy in the field, hemodynamic disorders or mechanical desynchrony deteriorated by intra or interventricular conduction abnormalities remains a critical target beyond the scope of pharmacotherapy. In the past 2 decades, nonpharmacologic treatment for heart failure, such as cardiac resynchronization therapy (CRT) via biventricular pacing (BVP), has been playing an important role in improving the prognosis of heart failure. However, the response rate of BVP-CRT is variable, leaving one-third of patients not benefiting from the therapy as expected. Considering the non-physiological activation pattern of BVP-CRT, more efforts have been made to optimize resynchronization. The most extensively investigated approach is by stimulating the native conduction system, e.g., His-Purkinje conduction system pacing (CSP), including His bundle pacing (HBP) and left bundle branch area pacing (LBBAP). These emerging CRT approaches provide an alternative to traditional BVP-CRT, with multiple proof-of-concept studies indicating the safety and efficacy of its utilization in dyssynchronous heart failure. In this review, we summarize the mechanisms of dyssynchronous HF mediated by conduction disturbance, the rationale and acute effect of CSP for CRT, the recent advancement in clinical research, and possible future directions of CSP.

Atrial-His bundle pacing in fulminant myocarditis with ventricular arrhythmia: a case report

BackgroundFulminant myocarditis is a clinical syndrome associated with threatening dysrhythmia which temporary pacemaker can be used for life-saving support. As a method of physiological pacing, His bundle pacing (HBP) maintain better cardiac synchronization than traditional right ventricular (RV) pacing.Case presentationIt’s a severe case of fulminant myocarditis in a 41-year-old patient who presented for recurrent arrhythmias with hemodynamic instability. Temporary His bundle pacing combined with optimal medical therapy and extracorporeal membrane oxygenators (ECMO) supported him through his critical period of hospitalization.ConclusionsDuring 1-year follow up, the cardiac function recovery was obvious without any pacing related complications. Echocardiography showed better atrioventricular and intra-ventricular synchronization during HBP in DDD mode. This is the first reported case of temporary His-purkinje conduction system pacing used for severe fulminant myocarditis.

The review of atrioventricular node ablation combined with His-Purkinje conduction system pacing in the treatment of atrial fibrillation and heart failure

心房颤动是成年人中最常见的持续性心律失常，心房颤动伴快速心室率是引起心力衰竭的重要原因之一。房室结消融联合希氏-浦肯野系统起搏是可行、有效的，尤其适用于难以耐受药物治疗或药物治疗无效、导管射频消融治疗失败的心房颤动伴快速心室率合并心力衰竭的患者。本文对房室结消融联合希氏-浦肯野系统起搏治疗心房颤动伴快速心室率合并心力衰竭的研究进展作一综述。.

Research progress on His-Purkinje Conduction System Pacing in patients with heart failure and left bundle branch block

左束支传导阻滞（LBBB）可导致心室电传导延迟、收缩不同步，是加重心力衰竭（心衰）的重要因素，亦是心衰治疗的重要靶点。传统双心室起搏可纠正LBBB、改善心功能，但其受到技术及解剖的限制，仍有部分患者难以从中获益。随着对希氏-浦肯野系统认识的深入、导线置入工具的改进及技术的发展，希氏-浦肯野系统起搏作为一种生理性起搏方式，成为当前研究的热点。希氏-浦肯野系统起搏可纠正LBBB、恢复电机械同步性，有望作为传统双心室起搏的替代疗法用于心衰伴LBBB患者。该文对希氏-浦肯野系统起搏在心衰伴LBBB患者中应用的理论及临床进展进行了综述。.

Conduction system pacing vs. biventricular pacing in patients with ventricular dysfunction and AV block.

It is unknown whether His-Purkinje conduction system pacing (HPCSP), as either His bundle or left bundle branch pacing, could be an alternative to cardiac resynchronization therapy (BiVCRT) for patients with left ventricular dysfunction needing ventricular pacing due to atrioventricular block. The aim of the study is to compare the echocardiographic response and clinical improvement between HPCSP and BiVCRT. Consecutive patients who successfully received HPCSP were compared with a historical cohort of BiVCRT patients. Patients were 1:1 matched by age, LVEF, atrial fibrillation, renal function and cardiomyopathy type. Responders were defined as patients who survived, did not require heart transplantation and increased LVEF ≥5 points at 6-month follow-up. HPCSP was successfully achieved in 92.5% (25/27) of patients. During follow-up, 8% (2/25) of HPCSP patients died and 4% (1/25) received a heart transplant, whereas 4% (1/25) of those in the BiVCRT cohort died. LVEF improvement was 10% ± 8% HPCSP versus 7% ± 5% BiVCRT (p=.24), and the percentage of responders was 76% (19/25) HPCSP versus 64% (16/25) BiVCRT (p=.33). Among survivors, the percentage of patients who improved from baseline II-IV mitral regurgitation (MR) to 0-I MR was 9/11 (82%) versus 2/8 (25%) (p=.02). Compared to those with BiVCRT, patients with HPCSP achieved better NYHA improvement: 1 point versus 0.5 (OR 0.34; p=.02). HPCSP in patients with LVEF ≤45% and atrioventricular block improved the LVEF and induced a response similar to that of BiVCRT. HPCSP significantly improved MR and NYHA functional class. HPCSP may be an alternative to BiVCRT in these patients. (Figure1. Central Illustration). [Figure: see text].

Short QRS Duration After His-Purkinje Conduction System Pacing Predicts Left Ventricular Complete Reverse Remodeling in Patients With True Left Bundle Branch Block and Heart Failure.

ObjectiveThis study aimed to explore the outcomes of His-Purkinje conduction system pacing (HPCSP) and to screen the predictors of left ventricular (LV) complete reverse remodeling in patients with true left bundle branch block (LBBB) and heart failure with reduced ejection fraction (HFrEF).MethodsPatients who underwent HPCSP for true LBBB and HFrEF from April 2018 to August 2020 were consecutively enrolled. All participants were followed up for at least 1 year. Thrombosis, infection, lead dislodgement, perforation, and other complications were observed after HPCSP. Clinical data, including echocardiographic parameters, electrocardiogram measurements, and cardiac function, were assessed before and after the procedure.ResultsA total of 46 patients were enrolled. HPCSP was successfully deployed in 42 cases (91.30%), which included 37 cases with His bundle pacing (HBP) and 5 cases with left bundle branch pacing (LBBP). The QRS duration decreased significantly (169.88 ± 19.17 ms vs. 113.67 ± 20.68 ms, P < 0.001). Left ventricular end-systolic volume (LVESV) (167.67 ± 73.20 ml vs. 85.97 ± 62.24 ml, P < 0.001), left ventricular end-diastolic diameter (LVEDD) (63.57 ± 8.19 mm vs. 55.46 ± 9.63 mm, P = 0.003) and left ventricular ejection fraction (LVEF) (26.52 ± 5.60% vs. 41.86 ± 11.56%, P < 0.001) improved dramatically. Complete reverse remodeling of the LV with normalized LVEF and LVEDD was found in nearly half of the patients (45.24%). A short QRS duration after HPCSP was a strong predictor of normalized LVEF and LVEDD (P < 0.001). The thresholds increased markedly in two patients approximately 6 months after HBP. No patients died during the total follow-up period of 20.07 ± 6.45 months.ConclusionComplete reverse remodeling of the LV could be found in nearly half of the patients with HFrEF and true LBBB after HPCSP, and the short QRS duration after HPCSP was a strong predictor.

CI-569-04 SEPTAL FLASH CORRECTION WITH HIS-PURKINJE PACING PREDICTS ECHOCARDIOGRAPHIC RESPONSE IN RESYNCHRONIZATION THERAPY

His-Purkinje conduction system pacing (HPCSP) has been proposed as an alternative to cardiac resynchronization therapy (CRT); however, no predictors of echocardiographic response have been described. Septal flash (SF) is a marker of intraventricular dyssynchrony. The study aimed to analyze whether HPCSP corrects SF in patients with CRT indication, and if correction of SF predicts echocardiographic response. Prospective observational study (n=30). Left ventricular ejection fraction (LVEF) was measured with echocardiography at baseline and at 6-month follow-up. Echocardiographic response was defined as increase in 5 points LVEF. ECG Imaging was performed (CardioInsight Mapping Vest-Medtronic) in 2 patients to validate ventricular activation shortening and to study the basal and HPCSP activation pattern. HPCSP shortened QRS duration by 48±21ms and SF was significantly decreased (baseline 3.6±2.2mm vs HPCSP 1.5±1.5mm p<0.0001). At 6-months, mean LVEF improvement was 8.6% ± 8.7% and 64% of patients were responders. There was a significant correlation between SF correction and increased LVEF (r=0.61, p=0.004). A correction of ≥1.5mm had 81% sensitivity and 80% specificity to predict echocardiographic response (area under curve 0.86, p=0.019). HPCSP improves intraventricular dyssynchrony and results in 64% echocardiographic responders at 6-month follow-up. Dyssynchrony improvement with SF correction may predict echocardiographic response at 6-month follow-up (Fig.1.).

PO-643-06 EVALUATION OF ELECTROCARDIOGRAPHIC AND INTRACARDIAC ELECTROGRAM CHARACTERISTICS FOR RESPONSE TO HIS-PURKINJE CONDUCTION SYSTEM PACING IN PATIENTS WITH LEFT BUNDLE BRANCH BLOCK CORRECTED BY HIS BUNDLE PACING

His-Purkinje conduction system pacing (HPCSP) has been proved to improve clinical outcomes in patients with left bundle branch block (LBBB) and heart failure. However, some patients still remain non-responsive to HPCSP.

PO-648-06 FEASIBILITY AND CLINICAL BENEFITS OF REIMPLANTATION OF HIS-PURKINJE CONDUCTION SYSTEM PACING LEAD

His-Purkinje conduction system pacing (HPCSP) proves to be safe and feasible over the long-term follow-up. However, lead-related complications such as increasing of his capture threshold, dislodgement, infection, hematoma etc. may require lead extraction and reimplantation.

Septal flash correction with His-Purkinje pacing predicts echocardiographic response in resynchronization therapy.

BackgroundHis‐Purkinje conduction system pacing (HPCSP) has been proposed as an alternative to Cardiac Resynchronization Therapy (CRT); however, predictors of echocardiographic response have not been described in this population. Septal flash (SF), a fast contraction and relaxation of the septum, is a marker of intraventricular dyssynchrony.MethodsThe study aimed to analyze whether HPCSP corrects SF in patients with CRT indication, and if correction of SF predicts echocardiographic response. This retrospective analysis of prospectively collected data included 30 patients. Left ventricular ejection fraction (LVEF) was measured with echocardiography at baseline and at 6‐month follow‐up. Echocardiographic response was defined as increase in five points in LVEF.ResultsHPCSP shortened QRS duration by 48 ± 21 ms and SF was significantly decreased (baseline 3.6 ± 2.2 mm vs. HPCSP 1.5 ± 1.5 mm p < .0001). At 6‐month follow‐up, mean LVEF improvement was 8.6% ± 8.7% and 64% of patients were responders. There was a significant correlation between SF correction and increased LVEF (r = .61, p = .004). A correction of ≥1.5 mm (baseline SF – paced SF) had a sensitivity of 81% and 80% specificity to predict echocardiographic response (area under the curve 0.856, p = .019).ConclusionHPCSP improves intraventricular dyssynchrony and results in 64% echocardiographic responders at 6‐month follow‐up. Dyssynchrony improvement with SF correction may predict echocardiographic response at 6‐month follow‐up.

His-Purkinje Conduction System Pacing inAtrioventricular Block: New Insights Into Site of Conduction Block.

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. 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). 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. 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 ± 0.7V at 0.9 milliseconds vs 0.6 ± 0.3V 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. 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.

Abstract 13982: Evaluation of Electrocardiographic and Intracardiac Electrogram Characteristics for Response to His-Purkinje Conduction System Pacing in Patients With Left Bundle Branch Block Corrected by His Bundle Pacing

Introduction: His-Purkinje conduction system pacing (HPCSP), including His bundle pacing (HBP) and left bundle branch pacing has been proved to improve clinical outcomes in patients with left bundle branch block (LBBB) and heart failure. However, some patients still remain non-responsive to HPCSP. We aimed to evaluate the effect of electrocardiographic and intracardiac electrogram characteristics for response to HPCSP in patients with typical LBBB which could be corrected by HBP. Methods: Consecutively enrolled patients with typical LBBB and baseline LVEF ≤40% from January 2012 to June 2020 who were able to achieve LBBB correction during HBP and implanted HPCSP. Baseline QRS duration, paced QRS duration, ΔQRSd, H-QRSend and ΔQRSend/H-QRSend were measured during the implantation. A 1-year absolute increase in LVEF≥15% identified super-response to HPCSP. Results: A total of 123 patients were included in the study (mean age 68.2±10.6 years; male 52.0%). Baseline characteristics of patients with ΔLVEF≥15% (N=93) and ΔLVEF&lt;15% (N=30) were comparable except for larger ΔQRSend/H-QRSend (0.42±0.07 vs 0.35±0.08 ms, p&lt;0.001), smaller baseline QRS duration (161.9±15.5 vs 172.3±17.4 ms, p=0.002) and paced QRS duration (100.9±14.9 vs 110.5±13.4 ms, p=0.002) in patients with ΔLVEF≥15%. Receiver-operating characteristic curve analysis demonstrated that a cut-off value of 0.39 for ΔQRSend/H-QRSend presented a sensitivity of 77% and specificity of 76% (AUC=0.776) to predict super-response to HPCSP. At multivariate analysis, larger ΔQRSend/H-QRSend, smaller paced QRS duration and baseline QRS duration remained predictors of super-response after HPCSP. Conclusions: HPCSP delivers favorable echocardiographic response in typical LBBB corrected by HBP. A larger ΔQRSend/H-QRSend, smaller baseline QRS duration and paced QRS duration are associated with a better response after HPCSP. ΔQRSend/H-QRSend is a novel and important predictor of LVEF increase.