Distance Between the Lead-Implanted Site and Tricuspid Valve Annulus in Patients With Left Bundle Branch Pacing: Effects on Postoperative Tricuspid Regurgitation Deterioration

Authors, Journal, Affiliations, Type, DOI

• Authors: Qingyun Hu and Hongzhao You (joint first authors); Keping Chen and Yan Dai (corresponding); Wenzhao Lu; Yao Li; Chendi Cheng; Yu'an Zhou; Jiaqi Wang; Ruohan Chen; Shu Zhang
• Journal: Heart Rhythm 2023;20(2):217–223. © 2022 Heart Rhythm Society
• Affiliations: State Key Laboratory of Cardiovascular Disease, Arrhythmia Center, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing; Endocrine Center, Fuwai Hospital; Department of Medicine, Peking Union Medical College Hospital
• Type: Single-centre prospective follow-up of a retrospectively identified cohort — 89 patients receiving LBBP January 2018 – August 2020, with echocardiography before and at last follow-up (19.0 ± 6.5 months)
• DOI: 10.1016/j.hrthm.2022.10.027
• Funding: National Natural Science Foundation of China (81870260). Disclosures: none declared

Overview

Tricuspid regurgitation is a known cost of transvenous pacing, but LBBP's specific contribution had been reported only once, at ~11%. This study measures tricuspid regurgitation before and after LBBP in 89 patients and finds that 29 (32.6%) worsened by at least one grade over a mean 19 months — a much higher figure than the earlier report, which the authors attribute to longer follow-up and a cohort enriched for patients with none/trivial TR at baseline. The novel finding is positional: in patients with relatively normal tricuspid valve function (none/trivial or mild TR, n=58), those who deteriorated had a shorter distance from the lead entry site on the right septal surface to the septal leaflet of the tricuspid annulus — 19.0 ± 7.6 vs 23.9 ± 5.4 mm (P = .006). A Lead-TA-dist ≤16.1 mm was an independent predictor (HR 0.20 for >16.1 mm; 95% CI 0.06–0.76; P = .017), with a ROC AUC of 0.721. The practical implication is that the Chinese consensus's 10–20 mm entry zone may need its lower bound raised to ~16 mm in patients with a normal tricuspid valve.

Keywords

Echocardiographic evaluation; Lead-implanted location; Left bundle branch pacing; Pacemaker complications; Tricuspid regurgitation

Key Takeaways

Cohort and definitions

• 89 patients, age 64.1 ± 13.4; male 42.7%
• Indications: AV block 55.0%, sick sinus syndrome 40.5%, AF/flutter with bradycardia 4.5%
• LVEF 62.7 ± 3.7%; NT-proBNP 252.1 ± 444.1 pg/mL
• Baseline TR: none/trivial 30 (33.7%), mild 28 (31.5%), moderate 23 (25.8%), severe 8 (9.0%)
• Grade 0/1 subgroup (none/trivial or mild): 58 (65.2%); grade 2/3 (moderate or severe): 31 (34.8%)
• Lead position by echocardiography at end-diastole, apical 3-/4-chamber view:
  • Lead-TA-dist 20.8 ± 6.7 mm (lead entry on the right septal surface to the septal leaflet of the tricuspid annulus)
  • Lead depth in the IVS 10.8 ± 2.1 mm
  • IVS thickness at the entry site 11.6 ± 2.2 mm
• TR graded 0–3 by two experienced sonographers using a multi-integrative approach including PISA; deterioration = an increase of at least one grade
• Exclusions: triple-chamber devices; switch to CRT or conventional RVP during follow-up; any tricuspid stenosis; prior or concurrent tricuspid surgery; congenital heart disease; age <18

Incidence

• TR deteriorated in 29/89 (32.6%) over 19.0 ± 6.5 months
• 23 of the 29 were in the grade 0/1 subgroup — 25.6% of that subgroup; 8 developed moderate and 4 severe TR
• In the grade 2/3 subgroup, 6 deteriorated
• Patients who deteriorated had shorter Lead-TA-dist (18.8 ± 7.0 vs 21.8 ± 6.5 mm, P = .016) and more hypertension (55.2% vs 31.7%, P = .04)

The grade 0/1 subgroup — the main analysis

• TR deteriorated in 23/58 (25.6%?) — reported as 23 patients (25.6%) in the text, which does not reconcile with 23/58 (39.7%). The denominator appears to be the whole cohort, not the subgroup; the text is ambiguous
• Lead-TA-dist was the only lead-position variable that differed: 19.0 ± 7.6 mm (deterioration) vs 23.9 ± 5.4 mm (no deterioration), P = .006
  • Lead depth (10.7 ± 1.4 vs 11.4 ± 2.4 mm, P = .17) and IVS thickness (11.7 ± 1.8 vs 12.2 ± 2.3 mm, P = .38) did not differ
  • Ventricular pacing proportion was similar (42.5 ± 48.5% vs 45.1 ± 45.1%, P = .83)
• ROC for Lead-TA-dist: AUC 0.721 (95% CI 0.575–0.867, P = .005); optimal cut-off 16.1 mm by the Youden index
• A Lead-TA-dist >16.1 mm reduced the risk of deterioration by 28.2% (P = .028) on Kaplan–Meier/log-rank
• Multivariable Cox in the grade 0/1 subgroup: Lead-TA-dist >16.1 mm HR 0.20 (95% CI 0.06–0.76, P = .017) — i.e. the longer distance is protective; hypertension HR 13.85 (2.08–92.44, P = .007) was the other independent predictor
• Age, male sex, coronary disease, diabetes, stroke, NT-proBNP, lead depth, IVS thickness and atrial tachyarrhythmia were not significant in that model

All-patient analysis

• Independent predictors of TR deterioration in the whole cohort: male sex HR 0.14 (0.03–0.63, P = .011) — i.e. female sex is the risk direction; diabetes HR 7.20 (1.35–38.49, P = .021); lead depth in the IVS HR 1.58 (1.03–2.45, P = .038)
• Lead-TA-dist was of only borderline significance in the whole cohort: HR 0.93 (0.87–1.00, P = .05) — the association is concentrated in the normal-valve subgroup
• In the grade 2/3 subgroup no significant relationship was found, which the authors attribute to limited sample size

Mechanism proposed

• A shorter Lead-TA-dist places the lead closer to the tricuspid annulus and subvalvular apparatus, increasing the chance of mechanical interference with leaflet or chordal motion during follow-up
• Supporting analogy: in leadless pacing, a septal position closer to the tricuspid valve was associated with more tricuspid incompetence than an apical position
• The practical proposal: target >16.1 mm from the septal leaflet — within the 10–20 mm range recommended by the 2021 Chinese consensus, but at its upper end — and consider intraoperative echo/ICE to measure the distance directly rather than estimating it fluoroscopically

Limitations of the document

Authors' own stated limitations

• Single-centre observational study; observational bias and inadequate statistical power from the limited sample
• A larger multicentre study is needed to define the optimal Lead-TA-dist range
• In the grade 2/3 subgroup the difference was not significant, attributed to small sample size
• The mechanism of lead-related TR deterioration remains unclear; the effects on right heart function and the relative contributions of leaflet/subvalvular interference versus pacing-induced electrical and mechanical change need further study

Additional limitations evident in the study

• The study has no control group. It cannot distinguish lead-related TR worsening from natural progression with age, atrial fibrillation, or ventricular remodelling — all plausible in a 64-year-old cohort followed for 19 months. The 32.6% incidence is therefore an upper bound on attributable harm, not a causal estimate
• The 32.6% figure conflicts with the other LBBP data in this wiki. The long-term Wenzhou cohort reported TR worsening in 11.1% and improvement in 31.4%; this study reports no improvement data and a threefold higher worsening rate. The authors attribute the difference to longer follow-up and more none/trivial TR at baseline, but the two studies also differ in TR grading, follow-up and case mix, and neither uses a core laboratory — so the true incidence is not established
• The endpoint is a one-grade change in a qualitative, reader-dependent measurement. Two sonographers agreed by consensus, but no interobserver variability, kappa, or blinding is reported; a one-grade shift is within the range that reader variation alone can produce
• The cut-off (16.1 mm) was derived and tested in the same 58 patients by the Youden index, then entered into the Cox model. The AUC of 0.721 is modest, and no external validation is reported
• The multivariable model is overfitted. In the grade 0/1 subgroup there are 23 events and a 10-variable model, and one estimate (hypertension HR 13.85, 95% CI 2.08–92.44) spans an implausibly wide range. The Lead-TA-dist HR should be read as hypothesis-generating
• The subgroup incidence statement is internally inconsistent: "23 patients (25.6%)" in a subgroup of 58 is 39.7%, not 25.6%. The 25.6% figure appears to use the whole cohort as denominator, which misstates the subgroup risk
• Lead-TA-dist was measured by transthoracic echocardiography at end-diastole in apical views, without reported reproducibility, and the lead entry site on the right septal surface can be difficult to identify precisely; the measurement error may be of the same order as the 16 mm cut-off
• No 3D echocardiography, no assessment of leaflet tethering, chordal interaction, or right ventricular remodelling, so the mechanism remains inferential
• The cohort excludes CRT, tricuspid surgery and congenital disease, limiting generalisability to the CRT population where TR matters most
• Follow-up is 19 months, too short to capture progressive TR or its clinical consequences (heart failure, mortality)
• The abstract's causal wording is directionally confusing: "Lead-TA-dist ≤16.1 mm was independently associated with TR deterioration (HR 0.20)" — the HR of 0.20 actually belongs to >16.1 mm (protective), so the sentence should be read as "≤16.1 mm increases risk"
• Rating rationale: rated medium. It addresses a real and under-studied complication, provides a plausible and actionable positional predictor, and uses a reasonable echo protocol. But it is single-centre, uncontrolled, small, overfitted, with a soft qualitative endpoint, a cut-off derived and tested in the same cohort, an internally inconsistent subgroup figure, and an incidence that conflicts threefold with the other LBBP series in this wiki

Key Concepts Mentioned

• concepts/Tricuspid-Regurgitation — the complication being studied
• concepts/Left-Bundle-Branch-Area-Pacing — the technique
• Lead-TA-dist — distance from the lead entry site on the right septal surface to the septal leaflet of the tricuspid annulus; ≤16.1 mm associated with TR deterioration
• Lead depth in the IVS — entry site to lead tip; deeper placement was associated with TR deterioration in the whole cohort
• IVS thickness at the entry site
• TR grade 0–3 — none/trivial, mild, moderate, severe; deterioration = ≥1 grade
• Proximal isovelocity surface area (PISA) — used in the qualitative grading
• Mechanical interference — the proposed mechanism: lead proximity to the tricuspid annulus and subvalvular apparatus
• The 10–20 mm consensus entry zone — Chinese expert consensus; this study suggests the lower bound should be above ~16 mm in normal valves

Key Entities Mentioned

• concepts/Left-Bundle-Branch-Area-Pacing — primary concept page
• concepts/Tricuspid-Regurgitation — the entity page
• Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing — the investigating centre
• Keping Chen; Yan Dai; Shu Zhang; Qingyun Hu; Hongzhao You — the investigators
• Medtronic 3830 lead and C315HIS sheath — the implant system
• Philips EPIQ 7C — the echocardiography platform
• Bard LabSystem Pro — the EP recording system
• Beurskens et al. — the leadless-pacemaker analogy for septal position and TR
• Heart Rhythm Society / Elsevier — publisher

Wiki Pages Updated

• Created: wiki/sources/tricuspid-regurgitation-lbbap-hrs-2023.md
• Updated: wiki/concepts/Left-Bundle-Branch-Area-Pacing.md
• Updated: wiki/concepts/Tricuspid-Regurgitation.md
• Updated: wiki/sourceindex.md
• Updated: wiki/wikiindex.md