Although His bundle pacing (HBP) can provide a physiologic ventricular activation pattern, it has disadvantages such as the difficulty of lead implantation, reduced R wave amplitudes, and high and unstable pacing thresholds. Recent studies have demonstrated that left bundle branch area pacing (LBBaP) might overcome these deficiencies. A total of 7 nonrandomized controlled studies including 786 patients (n = 442 receiving LBBaP and n = 344 receiving HBP) with bradyarrhythmia were evaluated. Compared with HBP, LBBaP appeared to result in increased R wave amplitudes (at implant: MD 9.84 mV, 95% confidence interval [CI] 7.61 to 12.06 mV; at follow-up: MD 7.62 mV, 95% CI 6.73 to 8.50 mV), lowered capture thresholds (at implant: MD −0.73 V, 95% CI −0.81 to −0.64 V; at follow-up: MD −0.71 V, 95% CI −0.92 to −0.50 V), shortened procedure times (MD −16.70 minutes, 95% CI −26.51 to −6.90 minutes) and fluoroscopic durations (MD −6.16 min, 95% CI −8.28 to −4.03 minutes), and increased success rates (odds ratio 2.14, 95% CI 1.23 to 3.74); all of these differences were significant. However, paced QRS durations, the lead impedance at implantation and follow-up, and incidence of lead-related complications such as lead dislodgement did not significantly differ between LBBaP and HBP. In conclusion, current evidence suggests that LBBaP is a potential alternative to HBP as a pacing modality with which to maintain an ideal physiologic pattern of ventricular activation through native His–Purkinje system stimulation.
His bundle pacing (HBP) has several benefits, including the ability to prevent pacing-induced cardiomyopathy and to physiologically resynchronize the left bundle branch block. However, the widespread adoption of HBP is hindered by challenging implantation techniques, reduced R wave amplitudes, and high and unstable pacing capture thresholds. Furthermore, follow-up can be problematic because of atrial signal oversensing, ventricular signal undersensing, lead displacement, and rising capture thresholds with premature battery depletion. Left bundle branch area pacing (LBBaP) in which the lead is fixed deep in the left side of the intraventricular septum to target the left bundle, distal to the His bundle, has been reported as a solution to these problems.
Methods
A systematic review and meta-analysis were conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. The databases PubMed, Embase, Medline, Web of Science, and Cochrane Library were searched for relevant trials performed before June 30, 2021. Inclusion criteria were as follows: (1) study design of a randomized controlled trial (RCT), a prospective cohort study, or a retrospective observational study; (2) meeting the standard indication for pacing therapy according to 2013 European Society of Cardiology guidelines; and (3) clear evaluation and report of clinical outcomes, such as various pacing parameters, echocardiographic parameters, procedural time, fluoroscopy duration, implant success rate, and lead-related complications. Exclusion criteria were (1) inadequate data or outcome, (2) inaccessibility of full article or incomplete full text, and (3) not in English. Two independent reviewers conducted the trial selection (ZY and LC); any disagreements were adjudicated by a third reviewer (YW).
The data extracted included the number of patients, follow-up duration, implant success rate, baseline characteristics of patients, indication for implantation, QRS duration (QRSd) at implant and follow-up, pacing thresholds at implant and follow-up, R wave amplitudes at implant and follow-up, lead impedances at implant and follow-up, and lead-related complications. Data were independently extracted by 2 authors (ZY and LC); any disputes were settled by another author (YW).
The risk of bias in the included RCTs was assessed using the Cochrane Handbook. The quality of the included nonrandomized controlled studies were independently evaluated by 2 authors (ZY and LC) using the Newcastle Ottawa Scale (NOS). Three aspects, that is, study group selection, group comparability, and outcome of interest determination were assessed using the NOS; studies that scored ≥6 points were considered to be of high quality.
Mean differences (MDs) for continuous outcomes, odds ratios (ORs) for binary outcomes, and 95% confidence intervals (CIs) for MDs and ORs were calculated. Statistical heterogeneity was examined using the I 2 test. If I 2 was <50%, which indicated significant homogeneity, a fixed-effects model was used; otherwise, a random-effects model was used. All p values were 2-tailed, and statistical significance was set at 0.05. Potential publication bias was assessed by visual inspection of a funnel plot. Review Manager (RevMan) software ([Computer program] Version 5.4, The Cochrane Collaboration, 2020.) was used for the data analysis.
Results
A total of 816 articles were identified; 681 were screened after excluding duplicates. A total of 662 articles were excluded because they did not meet the inclusion criteria, with 19 articles assessed for eligibility. After assessment of the full-text articles, 12 were excluded for the following reasons: editorial/review article (n = 4), case report (n = 3), lacking overall data for HBP (n = 2), overlapping cohort (n = 1), not a human study (n = 1), and not in English (n = 1). The remaining 7 studies were included in the final systematic analysis ( Figure 1 ).
A total of 5 of the included studies were prospective cohorts; 3 studies , , were conducted with a parallel design, and 2 13,14 had a crossover design. LBBaP or HBP was used for cardiac resynchronization therapy in 3 studies. , , The types of LBBaP reported included both selective LBBaP and nonselective LBBaP. The reporting rates of the outcomes of interest across the 7 included studies ranged from 16.7% (pacing threshold at follow-up and lead-related complications) to 100%. The basic elements of the included studies are listed in Table 1 .
| First author | Year | Study design | Number of patients (LBBaP/HBP) | Indication | Follow-up (months) | Evaluated parameters |
|---|---|---|---|---|---|---|
| Wang | 2019 | Prospective cohort | 8/44 | AF and AVN ablation, HF with narrow QRS duration/RBBB | 12 | pacing threshold, SC, LVEF, LVESV, HFH, mortality |
| Hou | 2019 | Prospective cohort | 56/29 | Bradycardia (SND, AVB, AF with SVR) | 4.5±2.4 | QRSd, pacing threshold, R wave amplitude, SC, PV interval, LVAT, PSD, LVEF, LVESD, LVEDD |
| Hu | 2020 | Prospective cohort | 22/19 | Bradycardia (AVB, BBB) | 3 | QRSd, pacing threshold, R wave amplitude, lead impedance, Pt, Fd, PSD, success rate, SC, LVEF, LVEDD |
| Hua | 2020 | Retrospective observational | 126/125 | Bradycardia (AVB, SND) | 3 | QRSd, pacing threshold, R wave amplitude, lead impedance, Pt, Fd, success rate, SC, LVEF, LVEDD |
| Qian | 2020 | Retrospective observational | 185/64 | Bradycardia (AVB, SND, AF with SVR), HF and wide QRS complex, AF and AVN ablation | 19.6±16.4 | QRSd, pacing threshold, R wave amplitude, success rate, SC, LVEDD, LVESD, LVEF, NYHA class, HFH |
| Wu | 2021 | Prospective cohort | 32/49 | LBBB, symptomatic HF | 12 | QRSd, pacing threshold, R wave amplitude, Pt, Fd, LVEF, LVEDV, LVESV, SC, NYHA class, HFH |
| Ye | 2021 | Prospective cohort | 13/14 | Bradycardia (AVB), AF and AVN ablation | 6 | lead impedance, SC, LVEF, LVEDD, NYHA class, HFH |
A total of 6 of the 7 included trials reported on the baseline comparability of the participants’ characteristics between treatment groups; most of the baseline patient characteristics were similar. The total population included 786 patients with permanent LBBaP (n = 442) or HBP (n = 344) implants. The average age was 66.5 years (n = 786, 95% CI 64.1 to 68.8 years), and 62.6% (n = 786, 95% CI 54.6% to 70.6%) of the patients were male. The average intrinsic QRSd was 117.0 ms (n = 745, 95% CI 97.3 to 136.6 ms). In total, 46.1% of the patients had a history of atrial fibrillation (n = 786, 95% CI 10.4% to 81.9%), and the most commonly reported indication for implantation was atrioventricular block (53.2%, n = 734). The average left ventricular (LV) ejection fraction was 53.5% (n = 496, 95% CI 43.3% to 63.6%). Heart failure (HF) in patients was reported in 4 of 7 studies. ,
All of the included studies had NOS scores >5, as listed in Table 2 . Moreover, we examined possible publication bias in the analysis of paced QRSd, R wave amplitude, and capture threshold, and funnel plots depicted no obvious publication bias ( Figure 2 ).
| Study | Representativeness of the exposed cohort | Selection of the nonexposed cohort | Ascertainment of exposure | Demonstration that outcome of interest was not present at start of study | Comparability of cohorts on the basis of the design or analysis | Assessment of outcome | Was follow-up long enough for outcomes to occur | Adequacy of follow up of cohorts | Total stars |
|---|---|---|---|---|---|---|---|---|---|
| Wang | * | * | * | * | * | * | * | * | 8 |
| Hou | * | * | * | * | ** | * | * | * | 9 |
| Hu | * | * | * | * | ** | * | * | * | 9 |
| Hua | * | * | * | * | ** | * | * | * | 9 |
| Qian | * | * | * | * | ** | * | * | * | 9 |
| Wu | * | * | * | * | ** | * | * | * | 9 |
| Ye | * | * | * | * | * | * | * | * | 8 |
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
