Significance of Muscle Health Assessment in Adolescent Fontan Patients: Handgrip Strength as an Early Screening Tool for Fontan-Associated Complications

Q: What are the key findings of this study?

Dynapenia and sarcopenia were associated with significantly lower %predicted peak VO2 (73.8% and 48.8% vs 89.6% in normal muscle group; p<0.01) in adolescent Fontan patients.

Q: What is the clinical evidence from this study?

Study design: Cross-Sectional. Population: Fontan circulation in adolescents (n=43). Intervention: Dynapenia (handgrip strength Z-score = -2.0 SD). Primary outcome: Exercise capacity (%predicted peak VO2) (p=<0.01).

Q: What does this research mean for the field?

Dynapenia and sarcopenia in adolescent Fontan patients are associated with significant stepwise reductions in exercise capacity and higher rates of severe complications despite normal resting hemodynamics. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

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

To assess the prevalence of muscle health abnormalities, including dynapenia and sarcopenia, and evaluate their relationship with exercise capacity, resting hemodynamics, and complications in adolescent Fontan patients.

Kouji Higashi; Hiromichi Nakajima; Hiroyuki Aotsuka

doi:10.21203/rs.3.rs-11333910/v1

October 26, 2026Open Access

Significance of Muscle Health Assessment in Adolescent Fontan Patients: Handgrip Strength as an Early Screening Tool for Fontan-Associated Complications

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Key result

Dynapenia and sarcopenia linked to markedly lower peak VO2 in adolescent Fontan patients.

P<0.01
n=43

Why the study?

Although skeletal muscle acts as a secondary pump in passive Fontan circulation, the prevalence and clinical significance of muscle health abnormalities like dynapenia and sarcopenia remain poorly defined in adolescent Fontan patients.

Does stratification of muscle health abnormalities (dynapenia and sarcopenia) via handgrip strength and DXA identify reduced exercise capacity and higher risk of Fontan-associated complications in adolescent Fontan patients?

Key Points

To assess the prevalence of muscle health abnormalities, including dynapenia and sarcopenia, and evaluate their relationship with exercise capacity, resting hemodynamics, and complications in adolescent Fontan patients.
Evaluated 43 adolescent Fontan patients (median age: 11.8 years) using dual-energy X-ray absorptiometry (DXA) for skeletal muscle mass index and handgrip strength (HGS).
Classified patients via Z-scores into Normal (N), Dynapenia (D: HGS Z-score < -2 SD, preserved mass), and Sarcopenia (S: both HGS and mass Z-scores < -2 SD).
Defined peak VO2 as the primary outcome and assessed resting hemodynamics, biomarkers, and Fontan-associated complications as secondary outcomes within a synchronized evaluation window.
Muscle abnormalities were identified in 31% of patients (n=13/43), categorized as dynapenia in 19% (n=8) and sarcopenia in 12% (n=5), with 70% (n=30) classified as normal.
Peak VO2 demonstrated a significant stepwise decline across the normal (89.6%), dynapenia (73.8%), and sarcopenia groups (48.8% of predicted; p<0.01).
Fontan-associated complications occurred at significantly higher rates in the dynapenia (50%, n=4/8) and sarcopenia groups (80%, n=4/5) than in the normal group (10%, n=3/30; p<0.01), despite resting hemodynamics and BNP showing no significant differences between the normal and dynapenia groups.

Study Design

Type

Cross-Sectional (n=43)

Multicenter

No

Structured PICO

Does stratification of muscle health abnormalities (dynapenia and sarcopenia) via handgrip strength and DXA identify reduced exercise capacity and higher risk of Fontan-associated complications in adolescent Fontan patients?

P

Population

43 clinically stable adolescent Fontan patients (median age 11.8 years) evaluated cross-sectionally within a 1-week window via DXA, handgrip strength, CPET, and invasive cardiac catheterization.

E

Exposure

Muscle health assessment and stratification using whole-body dual-energy X-ray absorptiometry (DXA) for appendicular skeletal muscle mass index (SMI) Z-scores and a calibrated dynamometer for handgrip strength (HGS) Z-scores into Dynapenia (HGS Z-score < -2.0 SD, SMI Z-score ≥ -2.0 SD; n=8) and Sarcopenia (both HGS and SMI Z-scores < -2.0 SD; n=5) phenotypes.

C

Comparator

Normal muscle health phenotype (preserved muscle mass and strength with SMI Z-score ≥ -2.0 SD and HGS Z-score ≥ -2.0 SD; n=30).

O

Outcome

Exercise capacity (%predicted peak VO2) measured via a bicycle ergometer symptom-limited cardiopulmonary exercise test with breath-by-breath gas analysis.surrogate

Main Result

Absolute Event Rate: 73.8% vs 89.6%

p-value: p=<0.01

Muscle health abnormalities affect nearly one-third of adolescent Fontan patients, and isolated muscle weakness (dynapenia) is strongly associated with reduced exercise capacity and a 50% rate of Fontan-associated complications despite normal resting hemodynamics, supporting routine handgrip strength screening.

Limitations

Single-center, retrospective study with a small sample size (N=43)
Cross-sectional design precludes establishing direct causality
East Asian pediatric reference data were used for DXA skeletal muscle mass index Z-scores due to the lack of a specific Japanese pediatric DXA database
Lower-limb muscle strength was not directly measured
Single-center, retrospective study with a small sample size
Cross-sectional nature precludes establishing direct causality; occult preload failure remains a speculative hypothesis requiring validation through dynamic exercise-stress catheterization
Use of East Asian reference data for SMI Z-scores due to the lack of a specific Japanese pediatric DXA database, whereas HGS Z-scores were derived from Japanese pediatric standards

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Implication

Handgrip screening may aid risk stratification in Fontan adolescents; leaves open whether sarcopenia-targeted interventions improve peak VO2.

Abstract

Background Skeletal muscle acts as a secondary pump in passive Fontan circulation. However, the prevalence and clinical significance of muscle health abnormalities, such as dynapenia and sarcopenia, remain poorly defined in adolescent Fontan patients. Methods We evaluated 43 adolescent Fontan patients (median age: 11.8 years). Skeletal muscle mass index via DXA and handgrip strength (HGS) were expressed as Z-scores to classify patients into three phenotypes: Normal (N), Dynapenia (D: HGS Z-score < -2 SD, preserved mass), and Sarcopenia (S: both < -2 SD). Peak \(\:{VO}₂\) was defined as the primary outcome, while resting hemodynamics, biomarkers, and Fontan-associated complications were secondary outcomes. Results The prevalence of dynapenia and sarcopenia was 19% (n = 8) and 12% (n = 5), respectively (Normal: 70%, n = 30). Peak \(\:{VO}₂\) showed a significant stepwise decline across the N, D, and S groups (89.6%, 73.8%, and 48.8% of predicted, respectively; \(\:p<0.01\)). Resting cardiac index, central venous pressure, ejection fraction, and BNP showed no significant differences between the N and D groups. However, severe complications (e.g., protein-losing enteropathy) were markedly higher in the D (50%) and S (80%) groups than in the N group (10%; \(\:p<0.01\)). Conclusions Muscle health abnormalities affect nearly one-third of adolescent Fontan patients. Notably, patients with dynapenia may exhibit a high incidence of complications despite normal resting hemodynamics and laboratory data. These findings suggest a cardiac-skeletal muscle crosstalk. Thus, routine handgrip strength measurement serves as a simple, practical tool to identify high-risk patients during routine follow-up.

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Cite This Study

Higashi et al. (2026) conducted a cross-sectional in Fontan circulation in adolescents (n=43). Dynapenia (handgrip strength Z-score < -2.0 SD with preserved muscle mass) and Sarcopenia (both < -2.0 SD) vs. Normal muscle health (handgrip strength and skeletal muscle mass index Z-scores >= -2.0 SD) was evaluated on Exercise capacity (%predicted peak VO2) (p=<0.01). Dynapenia and sarcopenia were associated with significantly lower %predicted peak VO2 (73.8% and 48.8% vs 89.6% in normal muscle group; p<0.01) in adolescent Fontan patients.

synapsesocial.com/papers/6aee6bb371a7594806220a6d https://doi.org/10.21203/rs.3.rs-11333910/v1

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Significance of Muscle Health Assessment in Adolescent Fontan Patients: Handgrip Strength as an Early Screening Tool for Fontan-Associated Complications

Key Points

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

Significance of Muscle Health Assessment in Adolescent Fontan Patients: Handgrip Strength as an Early Screening Tool for Fontan-Associated Complications

Key Points

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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