Integrative and quantitive evaluation of the efficacy of his bundle related pacing in comparison with conventional right ventricular pacing: a meta-analysis

Comparisons of electrophysiological characteristics, pacing parameters and mid- to long-term effects in right ventricular septal pacing, right ventricular apical pacing and left bundle branch area pacing

Background

As a near-physiological pacing innovation, left bundle branch area pacing (LBBAP) has drawn much attention recently. This study was aimed to investigate the electrophysiological characteristics, unipolar/bipolar pacing parameters and mid- to long-term effects and safety of three different pacing methods and identify possible predictors of adverse left ventricular remodeling.

Methods

Ninety-two patients were divided into the LBBAP group, right ventricular septal pacing (RVSP) group and right ventricular apical pacing (RVAP) group. Baseline information, electrophysiological, pacing and echocardiographic parameters were collected.

Results

The three pacing methods were performed with a similar high success rate. The paced QRSd was significantly different among the LBBAP, RVSP and RVAP groups (105.93 ± 15.85 ms vs. 143.63 ± 14.71 ms vs. 155.39 ± 14.17 ms, p < 0.01). The stimulus to left ventricular activation time (Sti-LVAT) was the shortest in the LBBAP group, followed by the RVSP and RVAP groups (72.80 ± 12.07 ms vs. 86.29 ± 8.71 ms vs. 94.14 ± 10.14 ms, p < 0.001). LBBAP had a significantly lower tip impedance during the procedure and 3-month follow up as compared to RVSP and RVAP (p < 0.001). Higher bipolar captured thresholds were observed in LBBAP during the procedure (p < 0.001). Compared to the baseline values, there was a greater reduction in left ventricular end-diastolic dimension (LVEDD) in the LBBAP group (p = 0.046) and a significant enlargement in LVEDD in the RVAP group (p = 0.008). Multiple regression analysis revealed that the Sti-LVAT was a significant predictor of LVEDD at 12 months post-procedure. At the 24-h post-procedure, significant elevations were observed in the cTnI levels in LBBAP (p < 0.001) and RVSP (p < 0.05). More transient RBB injury was observed in LBBAP. But no significant difference was found in cardiac composite endpoints among three groups (p > 0.05).

Conclusions

LBBAP demonstrated a stable captured threshold, a low tip impedance and a high R-wave amplitude during the 12-month follow-up. Left ventricular remodeling was improved at 12 months post-procedure through LBBAP. The Sti-LVAT was a significant predictor of left ventricular remodeling. LBBAP demonstrated its feasibility, effectiveness, safety and some beneficial electrophysiological characteristics during this mid- to long-term follow-up, which should be confirmed by further studies.

Generating Evidence to Support the Physiologic Promise of Conduction System Pacing: Status and Update on Conduction System Pacing Trials

Conduction system pacing avoids the potential deleterious effects of right ventricular pacing in patients with bradycardia and provides an alternative approach to cardiac resynchronization therapy. We focus on the available observational and randomized evidence and review studies supporting the safety, feasibility, and physiologic promise of conduction system approaches. We evaluate the randomized data generated from the available clinical trials of conduction system pacing, which have led to the recent inclusion of CSP in international guidelines. The scope for future randomized trials will building on the physiologic promise of conduction system approaches and offering information on clinical end points is explored.

Risk factors of pacing dependence and cardiac dysfunction in patients with permanent pacemaker implantation

AIMS

Right ventricular pacing (RVP) dependence could impair left ventricular ejection fraction (LVEF). This study aimed to illuminate the relationship between RVP proportion and LVEF, as well as disclosing independent predictors of RVP dependence.

METHODS AND RESULTS

Patients indicated for permanent pacemaker implantation were included (2016-2020). The ventricular pacing lead was placed in right ventricular apex or septum. Pacing mode programming followed universal standard. Electrocardiographic, echocardiographic, and serological parameters were collected. RVP dependence was defined according to its influence on LVEF. This study was of case-control design. Included patients were matched by potentially confounding factors through propensity score matching. A total of 1183 patients were included, and the mean duration of follow-up was 24 months. Percentage of RVP < 80% hardly influenced LVEF; however, LVEF tended to decrease with higher RVP proportion. High degree/complete atrioventricular block (AVB) [odds ratio (OR) = 5.71, 95% confidence interval (CI): 3.66-8.85], atrial fibrillation (AF) (OR = 2.04, 95% CI: 1.47-2.82), percutaneous coronary intervention (PCI) (OR = 2.89, 95% CI: 1.24-6.76), maximum heart rate (HR_max ) < 110 b.p.m. (OR = 2.74, 95% CI: 1.58-4.76), QRS duration > 120 ms (OR = 2.46, 95% CI: 1.42-4.27), QTc interval > 470 ms (OR = 2.01, 95% CI: 1.33-3.05), and pulmonary artery systolic pressure (PASP) > 40 mmHg (OR = 1.93, 95% CI: 1.46-2.56) were proved to predict RVP dependence.

CONCLUSIONS

High RVP percentage (>80%) indicating RVP dependence significantly correlates with poor prognosis of cardiac function. High degree/complete AVB, AF, ischaemic aetiology, PCI history, HR_max  < 110 b.p.m., QRS duration > 120 ms, QTc interval > 470 ms, and PASP > 40 mmHg were verified as independent risk factors of RVP dependence.

His-purkinje system pacing upgrade improve the heart performances in patients suffering from pacing-induced cardiomyopathy with or without permanent atrial fibrillation

INTRODUCTION

The efficacy and safety of his-purkinje system pacing (HPSP) upgrades in patients with pacing-induced cardiomyopathy (PICM) and atrial fibrillation (AF) are still unknown.

METHODS AND RESULTS

Patients with PICM were continuously enrolled from January 2018 to March 2020. All patients were further divided into AF subgroup and sinus rhythm subgroup. Clinical data including echocardiographic examination parameters, electrocardiogram (ECG) measurements, and New York Heart Association (NYHA) classification, were assessed before and after the procedure. The HPSP upgrades, including his bundle pacing (HBP) and left bundle branch pacing (LBBP) were completed in 34 of 36 (94%) patients, Complications including electrode dislodged, perforation, infection or thrombosis were not observed in the perioperative period. During a mean of 11.52 ± 5.40 months of follow-up. The left ventricular ejection fraction (LVEF) increased significantly (33.76 ± 7.54 vs 40.41 ± 9.06, P < 0.001), and the QRS duration decreased (184.22 ± 23.76 ms vs 120.52 ± 16.67 ms, P < 0.001) after the upgrades. LVEDD reversed from 59.29 ± 7.74 mm to 53.91 ± 5.92 mm (P < 0.001), and the NYHA functional class also improved to 2.00 ± 0.76 from 2.55 ± 0.91 at the first follow-up (P < 0.001). The left atrium (LA) size also slightly decreased compared to the initial state (47.44 ± 7.14 mm VS 45.56 ± 7.78, P = 0.010). BNP significantly decreased from a median value of 458.06(256.35-755.10) to 172.31(92.69-552.14) (P = 0.004). The threshold did not increase significantly (1.18 ± 0.76 mv@0.4 ms vs 1.26 ± 0.91mv @ 0.4 ms, P = 0.581). These improvements in patients with AF were similar with those in patients without AF (P > 0.05).

CONCLUSIONS

HPSP upgrades improved the heart performance and reversed the left ventricular remodeling in patients suffering from PICM with or without AF, and it should be a promising choice in these patients.

Clinical outcomes of His-Purkinje conduction system pacing

His-Purkinje conduction system pacing (HPCSP) in the form of His bundle pacing (HBP) and left bundle branch pacing (LBBP) allows normal left ventricular activation, thereby preventing the adverse consequences of right ventricular pacing. HBP has been established for several years with centers from China, Europe, and North America reporting their experience. There is international guidance as to how to implant such systems with the differing patterns of His bundle capture clearly described. LBBP is a more recent innovation with potential advantages including improved pacing parameters. HPCSP has been extensively studied in a variety of indications including cardiac resynchronization therapy, atrioventricular node ablation, and bradycardia pacing. This review will focus on the clinical outcomes of HPCSP including mortality and morbidity of heart failure hospitalization and symptoms.

Should His Bundle Pacing Be Preferred over Cardiac Resynchronization Therapy Following Atrioventricular Junction Ablation?

Atrial fibrillation (AF) and heart failure (HF) are associated with high morbidity and mortality, which is particularly detrimental when patients develop rapid ventricular rates (RVR). Atrioventricular junction (AVJ) ablation with pacemaker implantation has been used as a method of achieving rate control in patients with incessant AF with RVR. Right ventricular only pacing is known to be harmful in the setting of HF. His bundle pacing (HBP) and biventricular (BiV) pacing both offer durable pacing solutions that offer more physiologic activation. This review describes the benefits and drawbacks of HBP and BiV pacing in HF patients after AVJ ablation.

Leadless pacemaker implantation: A feasible and reasonable option in transcatheter heart valve replacement patients

BACKGROUND

Leadless pacemakers (LPMs) have been shown to have lower postoperative complications than traditional permanent pacemakers but there have been no studies on the outcomes of LPMs in patients with transcatheter heart valve replacements (THVRs). This study determined outcomes of LPMs compared to transvenous single-chamber pacemakers (SCPs) post-THVR.

METHODS

This is a retrospective single-center study including 10 patients who received LPMs post-THVR between February 2017 and August 2018 and a comparison group of 23 patients who received SCP post-THVR between July 2008 and August 2018. LPM or SCP was implanted at the discretion of electrophysiologists for atrial fibrillation with slow ventricular response or sinus node dysfunction with need for single-chamber pacing only.

RESULTS

LPMs were associated with decreased tricuspid regurgitation (P = 0.04) and decreased blood loss during implantation (7.5 ± 2.5 cc for LPMs vs 16.8 ± 3.2 cc for SCPs, P = 0.03). Five LPM patients had devices positioned in the right ventricular septum as seen on transthoracic echocardiogram. Frequency of ventricular pacing was similar between LPM and SCP groups. In the LPM group, one case was complicated by a pseudoaneurysm and one death was due to noncardiac causes. There was one pneumothorax and one pocket infection in the SCP group.

CONCLUSIONS

In this small retrospective study, LPMs were feasible post-THVR and found to perform as well as SCPs, had less intraprocedural blood loss, and were associated with less tricuspid regurgitation. Further, larger studies are required to follow longer-term outcomes and complications.

Permanent His bundle pacing in heart failure patients: A systematic review and meta-analysis

BACKGROUND

Cardiac resynchronization therapy (CRT) is the standard-of-care therapy for the patients with heart failure and left ventricular (LV) dyssynchrony. However, approximately 30% of the patients show no response. Recent studies have shown that His bundle pacing (HBP) could be an alternative for the patients with CRT indications. The purpose of this study was to evaluate the efficacy of HBP in patients with heart failure.

METHODS

We searched PubMed and Embase databases for studies evaluating HBP in patients with heart failure and LV dyssynchrony. The successful rate of implantation, QRS duration, pacing threshold, LV function at baseline and follow-up, and mortality rates were extracted and summarized.

RESULTS

Eleven studies including 494 patients were included in this analysis. The overall successful rate for implantation was 82.4%. The main indications for HBP were CRT candidates and cardiomyopathy with atrial fibrillation undergoing atrioventricular node ablation. Permanent HBP resulted in narrow QRS duration of 116.3 ± 13.9 ms after implantation. LV functions, including echocardiographic parameters and clinical outcomes, significantly improved at follow-up (P < 0.001). However, there was a trend of increased capture and bundle branch block correction thresholds at follow-up compared to baseline (P = 0.01 and 0.02, respectively). During a mean follow-up of 23.7 months, 5.9% of the patients experienced heart failure-related hospitalization and the mortality rate was 9.1%.

CONCLUSION

Permanent HBP has shown promising results for heart failure patients in small observational studies. Randomized controlled trials are needed to assess the efficacy of HBP in these patients.

Correlation of pacing site in right ventricle with paced QRS complex duration

Background

Pacing from RV mid septum and outflow tract septum has been proposed as a more physiological site of pacing and narrower paced QRS complex duration. The paced QRS morphology and duration in different RV pacing sites is under continued discussion. Hence, this study was designed to address the correlation of pacing sites in right ventricle with paced QRS complex duration.

Methods

Two hundred fifty-two consecutive patients who underwent pacemaker implantation were enrolled. Baseline clinical characteristics were recorded for each patient. All patient underwent fluoroscopy, electrocardiogram and echocardiography post pacemaker implantation. Paced QRS duration was calculated from the leads with maximum QRS duration.

Results

Mean paced QRS (pQRS) duration was significantly higher in apical septum group with a mean of 148.9 ± 14.8 m s compared to mid septum (139.6 ± 19.9 m s; p-value 0.003) and RVOT septum (139.6 ± 14.8 m s; p-value 0.002) groups, respectively. There was no significant difference between mid-septal and RVOT septal pQRS duration. On multivariate analysis, female gender, baseline QRS duration and RVOT septal pacing were the only predictors for narrow pQRS duration (<150 msec).

Conclusion

RV mid-septal and RVOT septal pacing were associated with significantly lower pQRS duration as compared with apical pacing. Based on multivariate analysis RVOT septal pacing appears to be preferred and more physiological pacing site.

His bundle pacing

His bundle pacing (HBP) has recently emerged as a technique to avoid the negative effects of long-term right ventricular apical pacing. In addition to providing physiologic ventricular activation, HBP has been shown to correct underlying conduction abnormalities in certain patients. Although large prospective, randomized clinical trials have not yet been completed, the available observational clinical data support the safety and efficacy of this technique. Here, we review the physiology of the his bundle (HB) as it relates to HBP, describe the current clinical experience, and discuss future directions of this emerging therapy.