What is the clinical evidence from this study?

Study design: Cohort. Population: Atrioventricular Block (n=370415). Intervention: Lean Body Mass vs. null. Primary outcome: Composite of second-degree or third-degree A V block (HR 1.15 for men, HR 1.13 for women, 95% CI 1.09-1.21 for men, 1.05-1.22 for women, p=<0.001 for men, 0.001 for women).

What question did this study set out to answer?

This research aims to explore the relationship between lean body mass and atrioventricular block risk.

March 13, 2026Open Access

Lean Body Mass is the Independent and Predominant Anthropometric Variable Associated With Atrioventricular Block

Q: What are the key findings of this study?

Higher lean body mass was associated with a 15% higher risk of A V block in men (HR 1.15, 95% CI 1.09-1.21, P < 0.001) and a 13% higher risk in women (HR 1.13, 95% CI 1.05-1.22, P = 0.001).

Q: What question did this study set out to answer?

This research aims to explore the relationship between lean body mass and atrioventricular block risk.

Key Result

Higher lean body mass was associated with a 15% higher risk of A V block in men (HR 1.15, 95% CI 1.09-1.21, P < 0.001) and a 13% higher risk in women (HR 1.13, 95% CI 1.05-1.22, P = 0.001).

Key Points

This research aims to explore the relationship between lean body mass and atrioventricular block risk.
Analyzed data from 370,415 UK Biobank participants
Used bioimpedance analysis to measure lean body mass
Employed multivariable Cox regression for hazard ratio estimation
Evaluated primary outcomes as composite of second- or third-degree AV block and pacemaker implantation
Higher lean body mass correlated with a 15% increased risk of primary outcomes in men and 13% in women per 1-SD increase
Significant associations remained after adjusting for other anthropometric variables
Higher lean body mass linked to prolonged PQ interval
Sex differences in AV block risk were reduced after accounting for lean body mass

Study Design

Type

Cohort (n=370,415)

Multicenter

Yes

Structured PICO

Does higher lean body mass increase the risk of incident atrioventricular block in middle-aged adults?

Population

370,415 middle-aged participants (aged 40-69 years) from the UK Biobank who underwent whole-body bioimpedance analysis and had no prior history of second- or third-degree AV block or cardiac implantable electronic devices. Mean age 56.8 years, 52.4% women.

Intervention

Higher lean body mass (LBM) assessed via whole-body bioimpedance analysis (evaluated per 1-SD increase: 7.7 kg in men, 5.0 kg in women)

Outcome

Composite of second-degree or unspecified AV block or third-degree (complete) AV blockcomposite

Higher lean body mass is independently associated with an increased risk of incident atrioventricular block and prolonged PQ interval in both men and women.

Main Result

Effect estimate: HR 1.15 for men, HR 1.13 for women (95% CI 1.09-1.21 for men, 1.05-1.22 for women)

Absolute Event Rate: 0.75% vs 0.3%

p-value: p=<0.001 for men, 0.001 for women

Limitations

Bioimpedance does not directly measure LBM, which may introduce prediction errors.
Changes in LBM during follow-up were not considered.
ICD-10 and OPCS-4 codes may miss asymptomatic events.
Observational nature may imply residual confounding.
Findings lack generalizability to other age groups and ethnicities.

Abstract

AbstractBackground Information regarding the association between lean body mass (LBM) and atrioventricular (AV) block risk is lacking. Objective To determine the associations of LBM with AV block risk. Methods We analyzed 370,415 UK Biobank participants who underwent bioimpedance analysis and had no history of AV block or cardiac implantable electronic devices. The primary outcome was a composite of second- or third-degree AV block. Secondary outcomes included each component of the primary outcome and AV block-related pacemaker implantation. Adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) per 1-SD increase in LBM were estimated using multivariable Cox regression. Results The mean age was 56.8 years, and 52.4% were women. During a median 11.8-year follow-up, 1519 and 677 primary outcome events occurred in men and women, respectively. LBM per 1-SD increase (7.7 kg in men and 5.0 kg in women) was associated with a 15% (HR: 1.15, 95% CI: 1.09–1.21, PConclusion Higher LBM was associated with increased AV block risk in both sexes and with a higher prevalence of a prolonged PQ interval. Sex differences in AV block risk may be partly mediated by differences in LBM.

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