Clinical Outcomes of His Bundle Pacing Compared to Right Ventricular Pacing

His-bundle pacing is the best approach to physiological pacing.

EP News: Clinical

Rapid reversal of right ventricular pacing–induced cardiomyopathy by His bundle pacing

Permanent His-bundle pacing: Long-term lead performance and clinical outcomes

His bundle pacing improves left ventricular diastolic function in patients with heart failure with preserved systolic function

Although right ventricular pacing (RVP) may impair ventricular function, it is commonly used for advanced atrioventricular block (AVB) and normal or mildly reduced ejection fraction (EF). We aimed to compare His bundle pacing (HBP), biventricular pacing (BiVP), and RVP for advanced AVB in patients with normal or mildly reduced EF. MEDLINE, Embase, Cochrane CENTRAL, ClinicalTrials.gov, Scopus, and Web of Science were searched. Outcomes were all-cause death, heart failure hospitalizations (HFH), EF, left ventricular volumes, 6-minute walk test, and QRS duration. HBP or BiVP was compared with RVP. Subsequently, network meta-analysis compared the three pacing options. Our protocol was registered in PROSPERO (CRD42018094132). Six studies compared BiVP and RVP (704 vs 614 patients) and four compared HBP and RVP (463 vs 568 patients). Follow-up was 6 months to 5 years. There was significantly lower mortality and HFH with HBP or BiVP as compared with RVP (odds ratio [OR], 0.66, [0.51-0.85], P = .002; OR, 0.61 [0.45-0.82], P < .001, respectively]. HBP or BiVP also showed significant increase in EF and decrease in QRS duration (mean difference [MD], 5.27 [3.86-6.69], P < .001; MD -42.2 [-51.2 to -33.3], P < .001, respectively). In network meta-analysis, HBP and BiVP were associated with significantly improved survival compared to RVP, with surface under the cumulative ranking curve (SUCRA) probability of 79.4%, 69.4%, and 1.2% for HBP, BiVP, and RVP, respectively. For HFH, SUCRA probability was 91.5%, 57.2%, and 1.3%, respectively. HBP or BiVP were the superior strategies to reduce all-cause death and HFH for advanced AVB with normal or mildly reduced EF, with no significant difference between BiVP and HBP.

Funding Acknowledgements Type of funding sources: None. Introduction Despite optimal medical treatment, the 5-years mortality and HF readmission rate was 75.3% and 48.5%, respectively. The current guidelines recommended cardiac resynchronization therapy (CRT) by implanting biventricular pacing (BVP) for specific group of patients with HF with reduced ejection fraction (HFrEF) in order to reduce the mortality and the risk of HF events by 34%. However, 20% to 40% patients might not respond or even get clinical deterioration after receiving such device. To overcome the non-responders, His bundle pacing (HBP) emerges recently as one of the therapeutic options. His bundle pacing implantation potentially results in the narrower QRS duration as well as more improvement in left ventricle (LV) function compared with BVP in patients with LBBB. On top of that, HBP might become a more cost-effective solution, compared to CRT, particularly for the majority of developing countries in Asia. Purpose We aim to elaborate the clinical efficacy of HBP in specific patients with HF, compared to BVP. This HBP was implanted either as a primary therapeutic strategy for CRT candidates or as a rescue strategy for BVP non-responders. Methods This study is registered. A structured search was conducted in Pubmed, Embase, and Clinicaltrial.gov. Inclusion criteria were: Age &amp;gt;18 years old, NYHA II-IV, QRS duration ≥120 milliseconds, and left (LBBB) or right bundle branch block (RBBB) morphology. The primary endpoints were change in QRS duration, improvement in LVEF, improvement in NYHA class, and cardiovascular (CV) event. Results A total of 8 final articles involving 361 HF patients were included for analysis, with a male preponderance. The QRS duration was significantly narrower in HBP (MD: -23.44; 95%CI -34.92 to -11.97; P&amp;lt;0.001) compared to BVP. There was no statistically significant LVEF improvement between HBP group and BVP group in HF patients who were CRT candidates (MD: 4.63; 95%CI -4.47 to 13.74; P=0.32). The improvement in NYHA class varied between studies. One study reported comparable improvement between HBP and BVP, while another study reported better improvement in HBP compared to BVP. In terms of CV outcome, there was no significant difference in CV hospitalization and mortality rate. Heart failure hospitalization occurred both in HBP and BVP group, but the difference was not significant between groups. Improvement in QRS duration, LVEF, and NYHA class occurred in both LBBB and RBBB. Conclusion(s) HBP provides better electrical resynchronization compared to BVP. Additionally, some degree of reverse LV remodelling was also observed in HBP group of patients with either LBBB and RBBB patterns. However, the benefits of HBP in reducing HF hospitalization and CV mortality remain indeterminate. Further RCTs with large samples are still required to evaluate the superiority of HBP, compared to BVP for CRT, in reducing mortality and HF hospitalization.

Fusion of left ventricular pacing with intrinsic conduction provides superior resynchronization compared to biventricular pacing. His bundle pacing (HBP) preserves intrinsic conduction and allows for constant fusion with left ventricular pacing. This study evaluated sequential His bundle and left ventricular pacing for cardiac resynchronization therapy (CRT). In patients referred for CRT, sequential His bundle and left ventricular pacing was performed when HBP did not correct the QRS. At implant, QRS duration and area were compared between biventricular pacing and His bundle and left ventricular pacing. Devices were programmed for His and left ventricular pacing. Functional status and echocardiography were evaluated in follow up. Twenty-one patients, seven female, 70.7 ± 9.9 years, 57% with nonischemic cardiomyopathy were included. Baseline QRS duration was 170 ± 21 ms and was 157 ± 16 ms with HBP. Biventricular pacing resulted in a QRS duration of 141 ± 15 ms and decreased to 110 ± 14 ms with His bundle and left ventricular pacing (p < .0005). His bundle and left ventricular pacing resulted in a smaller paced QRS area (38.5 ± 22.6 µVs) compared to biventricular pacing (67.5 ± 24.0 µVs) and baseline (78.1 ± 28.1 µVs; p < .0005). Left ventricular ejection fraction increased from 27.6 ± 6.4% to 41.1 ± 12.5 (at 25 mean months, p = .001) and functional class improved from 3.1 ± 0.5 to 2.1 ± 0.8 (at mean 32 months, p < .001). Sequential His bundle and left ventricular pacing results in superior electrical synchrony in patients with indication for CRT when HBP does not correct the QRS and resulted in promising clinical and echocardiographic response rates.

Pacemaker implantation with right ventricular pacing is widely used in clinical practice in the treatment of bradycardia, especially in patients with symptomatic AV block. However, right ventricular apical pacing (RVAP) sometimes induces electromechanical dyssynchrony, leading to adverse clinical impacts on clinical outcomes, including an increased risk of new-onset atrial arrhythmias. Physiological conduction system pacing (CSP), His bundle pacing (HBP), and left bundle area pacing (LBBAP) are recommended for patients with reduced left ventricular (LV) systolic function and substantial ventricular pacing (>20%) since CSP has been reported to improve clinical outcomes compared with RVAP. Although several studies suggest that CSP is associated with a lower incidence of new-onset atrial arrhythmias detected as atrial high-rate episodes (AHRE), the performance between HBP pacing and LBBAP on the risk of new-onset AHRE remains unclear. Pestrea et al. showed that HBP and LBBAP were associated with a similar incidence of device-detected new-onset AHRE during a medium-term follow-up period in patients with atrioventricular block.1 They compared the incidence of device-detected new-onset AHRE between the two groups of patients after HBP (n = 59) and those after LBBAP (n = 83) during a mean follow-up of 624 days. New-onset AHRE occurred in 8 (13.5%) in the HBP group and in 14 (16.8%) in the LBBAP group. Multivariable Cox regression analysis showed that HBP and LBBAP had similar predictive values for device-detected new-onset AHRE. Moreover, there was no significant difference between the two groups regarding the total burden of AHRE, which was less than 1% in almost all patients with new-onset AHRE, although there were several limitations such as using different criteria of the current 2020 ESC guideline, which indicated the device-programmed rate criterion for AHRE is greater than or equal to 175 bpm and the duration criterion is greater than or equal to 5 min.2 Cardiac electronic implantable devices such as pacemakers have the ability to monitor rhythm abnormalities, which allow us to recognize a new entity of AHRE easily. From a clinical point of view, AHRE has been associated with the development of clinical atrial fibrillation (AF) and an increase in stroke and death risk. There have been reports about the risk factors for AHRE including older age, left atrial volume, prior history of AF, white cell count, high levels of C reactive protein, and CHADS2 score.3 As for the issue related to new-onset AHRE after implantation, a high burden of RVAP is a risk for increased AHRE since RVAP induces paradoxical septal motion and ventricular dyssynchrony. As a result, increased filling pressure in each heart chamber leads to electric remodeling of the left atrium. CSP restores ventricular contraction synchrony by pacing the His-Purkinje conduction system directly, which allows for rapid and widespread dissemination of ventricular activation throughout the ventricle. CSP, including both HBP and LBBAP, has several advantages of LV function, subsequent events of heart failure hospitalization, and the incidence of new-onset AHRE during a follow-up compared to RVAP, especially in patients with LV dysfunction and a high burden of right ventricular pacing.4 There are some limitations of relatively low procedural success rates and the development of a high and unstable pacing threshold in terms of HBP, although it has demonstrated several clinical benefits. In addition, HBP is inefficient as physiological pacing if a patient has infra-Hisian distal conduction block. There are several strong points of LBBAP, including the wide target area of left bundle and Purkinje fibers on the LV septum and a stable low pacing threshold with no significant sensing issues. In fact, a previous meta-analysis revealed that LBBP was significantly associated with higher implant success rates (relative risk: 1.12), lower capture threshold at implantation (mean difference [MD]: 0.63 V at 0.5 ms) and lower capture threshold at follow-up (MD: 0.76 V at 0.5 ms) compared with HBP.5 These data suggest that pacing characteristics are better in LBBAP than in HBP; however, the incidence of new-onset AHRE during a follow-up may be similar between patients with LBBAP and those with HBP by taking the current issue into consideration. At this moment, it remains controversial which we should select: LBBAP or HBP. Large-scale, randomized control studies are warranted to reveal the true answer. Dr. Noda reports Grants-in-Aid for Scientific Research (22K08092) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan and declares receiving fees for speakers from Medtronic Japan and Biotronik Japan.

Permanent His-bundle pacing is feasible, safe, and superior to right ventricular pacing in routine clinical practice.

Painful left bundle branch block syndrome treated successfully with permanent His bundle pacing

Background Atrioventricular (AV) node ablation with biventricular (BiV) pacemaker implantation is a feasible rate control strategy for symptomatic permanent atrial fibrillation (AF) with rapid ventricular response and tachycardia-induced heart failure (HF). However, certain controversy exists since BiV pacing delivers non-physiological ventricular resynchronization and does not return left ventricular (LV) activation times to those seen in individuals with intrinsically narrow QRS. Permanent His bundle pacing (HBP) is a physiological alternative to conventional and BiV pacing. By capturing the native conduction system, depolarization of the ventricles through the His-Purkinje system induces normal synchronous ventricular activation. Purpose The aim of the study was to compare short-term outcomes between BiV pacing and HBP after AV node ablation in HF patients with symptomatic permanent AF and narrow QRS. Methods A total of 25 consecutive HF patients with permanent AF and narrow QRS (≤110 ms) who underwent AV node ablation in conjunction with BiV pacing or HBP in our centre were enrolled. Post-implant QRS duration, echocardiographic data, and New York Heart Association (NYHA) functional class were assessed in short-term follow-up. Results Among 25 HF patients (aged 68 ± 7 years, 52% female, QRS 96 ± 9 ms, LVEF 37 ± 7%, NYHA II-IV), 13 received BiV pacing and 12 HBP. Implant and ablation procedures were acutely successful in both groups. In BiV group 1 patient had a LV lead dislodgement and 1 patient in the HBP group had an acute HB lead threshold increase after AV node ablation. In HBP group post-implant QRS duration was shorter compared to BiV (103 ± 15 ms vs. 177 ± 13 ms, p &amp;lt; 0.001). At a median follow-up of 6 months, patients treated with HBP had greater increase in LV ejection fraction compared to BiV (44 ± 10 vs. 37 ± 6, p = 0.045). A trend toward greater reduction of LV volumes (EDV 119 ± 54 ml vs. 153 ± 33 ml, p = 0.07; ESV 75 ± 34 ml vs. 97 ± 26 ml, p = 0.09) and improvement of NYHA class (2.1 ± 0.7 vs. 2.7 ± 0.8, p = 0.08) was also observed in HBP group compared to BiV group. Conclusion In rate control refractory HF patients with permanent AF and narrow QRS atrioventricular node ablation in conjunction with HBP demonstrated superior electrical resynchronization and greater increase in LV ejection fraction compared to BiV pacing. Larger prospective studies are warranted to address clinical outcomes between both pace and ablate strategies.

Left bundle pacing in transposition of the great arteries with previous atrial redirection operation

QT interval prolongation and torsade de pointes induced by left ventricular pacing rescued by His bundle pacing

Funding Acknowledgements Type of funding sources: None. Background Atrioventricular node ablation (AVNA) with biventricular (BiV) pacing is an established treatment option for heart failure (HF) patients with drug refractory atrial fibrillation (AF) (1). However, compared to conduction system pacing (CSP) modalities, including His bundle pacing (HBP) and left bundle branch pacing (LBBP), BiV pacing delivers non-physiological ventricular activation (2). Purpose To compare clinical outcomes of BiV pacing and both CSP modalities in HF patients with symptomatic AF who underwent AVNA. Methods Consecutive AF patients with LV ejection fraction (LVEF &amp;lt;50%) who received either BiV pacing or CSP in conjunction with AVNA between May 2015 and July 2021 were retrospectively analysed. Procedural characteristics, electrocardiographic, echocardiographic, and clinical parameters were assessed at baseline and 6 months after the procedure. Results Fifty-five patients (male 43.6%, age 71 years (IQR 10), LVEF 39% (IQR 14)) were included. Thirteen patients (23.6%) received BiV pacing, 30 patients (54.5%) HBP and 12 patients (21.8%) LBBP. All groups had similar baseline characteristics, acute success rate and adverse events. Post-procedural QRS duration was significantly shorter (p&amp;lt;0.01) in CSP (118 ms (IQR 28)) than in BiV pacing (172 ms (IQR 18)). While NYHA class improved in both HBP (p&amp;lt;0.01) and LBBP (p=0.01), it did not improve in BiV group (p=0.1) At follow-up, end systolic volume (ESVi) decreased in both HBP (48±20 to 32±12 mL/m2, p&amp;lt;0.01) and LBBP (62±22 to 52±22 mL/m2, p=0.02), but did not differ in BiV pacing group (51±12 to 53±14 mL/m2, p=0.6). Similarly, LVEF increased in HBP (form 39% (IQR 16) to 53% (IQR 14), p&amp;lt;0.01) and LBBP (from 41% (IQR 23) to 40% (IQR 25), p=0.04), but did not change in BiV group (from 38% (IQR 5) to 37% (IQR 6), p=0.9). Significantly lower (p&amp;lt;0.01) pacing thresholds were achieved in LBBP (0.75 V at 0.5 ms (IQR 0.3)) than in HBP group (1.0 V at 0.5 ms (IQR 1)). Two patients in HBP group were switched to right ventricular pacing due to rise in HBP threshold. In the remaining patients threshold remained stable during follow-up. Conclusion Conduction system pacing modalities showed superior symptomatic and echocardiographic improvement compared to BiV pacing after AVNA. While LBBP offered lower and more stable pacing parameters, there were no differences in clinical outcomes and echocardiographic remodelling when compared to HBP.