Smaller Right Ventricle Results in Poorer Exercise Performance in Young Patients With Repaired Tetralogy of Fallot
Clinical Snapshot
PICO Framework
| P — Population | Young patients with surgically repaired tetralogy of Fallot and pulmonary insufficiency (n=37, mean age 17±5 years) |
| I — Intervention | Right ventricular size assessment via cardiac magnetic resonance imaging |
| C — Comparator | Varying degrees of right ventricular end-diastolic volume indexed to body surface area |
| O — Outcomes | Exercise performance measured by cardiopulmonary exercise testing, particularly peak oxygen consumption and oxygen pulse |
Bottom Line
This cross-sectional study challenges conventional thinking about right ventricular dilatation in repaired tetralogy of Fallot. In 37 young patients (mean age 17 years), smaller right ventricular volumes were paradoxically associated with worse exercise performance, contrary to the traditional view that RV dilatation indicates need for pulmonary valve replacement. The study used gold standard cardiac MRI and exercise testing, finding strong correlations between RV size and exercise capacity. While the sample size is modest and single-centre design limits generalisability, these findings suggest exercise intolerance in rTOF may represent a distinct pathological entity independent of RV dilatation. This has important implications for timing of pulmonary valve replacement decisions in Australian cardiac centres, suggesting that exercise capacity assessment should be considered alongside traditional volumetric criteria when evaluating these complex patients.
Key Findings
P Value: P=0.0004 for RVEDVi vs peak OP/BSA correlation
Effect Size: Strong positive correlation between RVEDVi and peak oxygen pulse/BSA
Primary Outcome: Peak oxygen consumption approximately 70% of predicted value
Nnt Or Sensitivity: Mean RVEDVi 127±28 mL/m², PRF 28.3±13.4%, RVEF 50.3±7.8%
Confidence Interval: Not reported
Clinical Application
Requires CMR and CPET facilities available in major Australian cardiac centres Relevant for Heart of a Child Foundation patients, applicable to RCH Melbourne, Sydney Children's Hospital cardiac programs Young patients with repaired tetralogy of Fallot and pulmonary insufficiency in Australian cardiac centres
Abstract
BACKGROUND: Severe right ventricular (RV) dilatation and exercise intolerance are considered indications for pulmonary valve replacement in surgically repaired tetralogy of Fallot (rTOF). METHODS AND RESULTS: Cardiopulmonary exercise testing (CPET) and cardiac magnetic resonance (CMR) were performed in rTOF patients with pulmonary insufficiency (PI). Oxygen pulse (OP), calculated as oxygen consumption (V̇O2)/heart rate, was used as a surrogate of stroke volume (SV). Correlations between CPET and CMR measures were investigated. In all, 37 patients (mean [±SD] age 17±5 years; 14 males) were examined. Peak V̇O2/kg was approximately 70% of predicted value. The pulmonary regurgitant fraction (PRF) was 28.3±13.4%. Body surface area (BSA)-indexed RV end-diastolic volume (RVEDVi) and RVSV (RVSVi) were 127±28 and 65±16 mL/m2, respectively. RV and left ventricular (LV) ejection fractions were 50.3±7.8% and 59.1±6.1%, respectively. A strong positive correlation was noted between RV end-diastolic volume and RVSV (P<0.0001), RVSV and LVSV (P<0.0001), and RVEDVi and peak OP/BSA (P=0.0004). Larger RVEDVi was correlated with better exercise performance, whereas smaller RVEDVi was correlated with worse exercise performance. RVEDVi was larger in male than female rTOF patients despite comparable PRF, RVSVi, LVEDVi, and BSA-indexed LVSV. CONCLUSIONS: A smaller RV was associated with worse exercise performance, indicating exercise intolerance is independent of RV dilatation in young rTOF with PI and represents a unique pathological entity responsible for reduced exercise performance.
References
- 1.Mhanna, C., Kourpas, K., & Tsuda, T. (2026). Smaller right ventricle results in poorer exercise performance in young patients with repaired tetralogy of Fallot. Circulation Journal, Advanced online publication. https://doi.org/10.1253/circj.CJ-25-0846
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