Cardiopulmonary Exercise Test (CPET) in patients with repaired Tetralogy of Fallot (rTOF); A systematic review

Cardiopulmonary Exercise Testing in Children and Adolescents with Repaired Tetralogy of Fallot: Mechanisms of Exercise Intolerance and Clinical Implications

By comparison with adults, cardiopulmonary exercise testing in children with Tetralogy of Fallot is limited, and its clinical application less clarified. This study provides a comprehensive CPET profile in a child-adolescent population with repaired TOF, explores mechanisms underpinning exercise intolerance and associations with clinical outcome. Seventy-four CPETs were completed in 58 child-adolescents with rTOF (age 13.8 SD 2.4 years). CPET parameters were corrected for age, sex and body size. At follow-up (4.9 years, IQR 3.5-7.9) clinical status and re-intervention was evaluated and CPET indices predicting these outcomes determined. Cohort peak V̇O2 was within low-normal limits (% pred: 74.1% SD 15.4) with 15 patients (26%) displaying moderately severe reduction in V̇O2peak (< 65% pred). Oxygen uptake efficiency slope highly correlated with V̇O2peak (r = 0.94, p < 0.001) and was insensitive to exercise intensity. No significant change in CPET occurred in patients who underwent interval testing at 24 SD 14.5 months, although there was a variable response in V̇O2peak between individuals. Chronotropic response, lung vital capacity, heart rate-V̇O2 slope (indicator of stroke volume) predicted oxygen consumption: V̇O2peak (R2 = 50.91%, p < 0.001) and workload (R2 = 58.39%, p < 0.001). Adverse clinical status was associated with reduced workload (OR 0.97, p = 0.011). V̇E/V̇CO2 slope was steeper in those that died ((%pred:137.8 SD 60.5 vs. 108.4 SD 17.0, p < 0.019). RVOT reintervention post-CPET (24 patients, 43.8%) was associated with an increased gradient of HR-VO2 slope (OR 1.042, p = 0.004). In child-adolescents with TOF important reductions in cardiopulmonary functioning were apparent in 25% of patients. Exercise intolerance was related to reduced vital capacity, impaired chronotropic response and deficient stroke volume increment.

Multimodality Imaging Assessment of Tetralogy of Fallot: From Diagnosis to Long-Term Follow-Up

Tetralogy of Fallot (TOF) is the most common complex congenital heart disease with long-term survivors, demanding serial monitoring of the possible complications that can be encountered from the diagnosis to long-term follow-up. Cardiovascular imaging is key in the diagnosis and serial assessment of TOF patients, guiding patients' management and providing prognostic information. Thorough knowledge of the pathophysiology and expected sequalae in TOF, as well as the advantages and limitations of different non-invasive imaging modalities that can be used for diagnosis and follow-up, is the key to ensuring optimal management of patients with TOF. The aim of this manuscript is to provide a comprehensive overview of the role of each modality and common protocols used in clinical practice in the assessment of TOF patients.

Differences in Cardiopulmonary Fitness Between Boy and Girls With Repaired Tetralogy of Fallot

OBJECTIVE

Many studies have demonstrated that patients with repaired tetralogy of Fallot (rTOF) have generally poorer cardiopulmonary fitness (CPF). However, little is known about how the disease results in different CPF in each sex. Therefore, this study aimed to investigate whether sex (and gender) differences affect CPF in children and adolescents with rTOF.

METHODS

This retrospective study recruited adolescents and children (aged 10-18) with rTOF following an acute stage of tetralogy of Fallot (TOF) who received cardiopulmonary exercise testing (CPET) in the past 10 years. CPF was determined by symptom-limited CPET with a treadmill under ramped Bruce protocol. Boys and girls were categorized into groups based on body mass index (BMI) and fat mass index (FMI). The BMI was grouped by Taiwanese obesity cutoff points. The FMI was categorized by the body fat percentage. Excess adiposity was defined as (1) "overweight" and "obese" by BMI and (2) greater than the sex- and age-specific 75th percentile of whole subjects by FMI.

RESULTS

A total of 185 participants (104 boys and 81 girls) with rTOF were recruited for the final analysis. Within the BMI category, 76 boys and 63 girls were in the normal group, whereas 28 boys and 18 girls were in the excessive adiposity group. Within the FMI category, 77 boys and 60 girls were in the normal group, whereas 27 boys and 21 girls were in the excessive adiposity group. The analysis of the body composition of rTOF subjects showed that there was no statistically significant difference between the subgroups of the two sexes, but both showed a smaller body size than normal Taiwanese children. When comparing the CPF within different BMI and FMI groups, the children in the excessive adiposity group had significantly lower values in metabolic equivalents (MET) at anaerobic threshold, peak MET, and measured peak oxygen consumption (VO₂) to predicted peak VO₂, regardless of sex. Moreover, boys (60.90%) presented poorer CPF than girls (74.22%, p < 0.001).

CONCLUSION

In Taiwan, patients with rTOF had poorer CPF than healthy peers. This study found that girls with rTOF had better CPF than boys with rTOF. The effect of gender stereotypes on sports participation and self-efficacy might be one of the contributing factors; however, further investigations are warranted to determine the causal effect.