The “Super-Fontan” Phenotype: Characterizing Factors Associated with High Physical Performance.
Tran DL, Celermajer DS, Ayer J, Grigg L, Clendenning C, Hornung T, Justo R, Davis GM, d’Udekem Y, Cordina R. Front Cardiovasc Med. 2021 Dec 7;8:764273. doi: 10.3389/fcvm.2021.764273. eCollection 2021. PMID: 34950712
Take Home Points:
- Fontan patients who were very active at a young age, have a normal BMI, had earlier Fontan completion and had left systemic ventricle are more likely to be associated with better exercise capacity or “Super-Fontan”.
- Super-Fontans are associated with better lung function and exercise self-efficacy.
- Super-Fontans were not affected by the type of Fontan circuits, the duration of Fontan and the presence of fenestration in the Fontan circuit.
- When the patients reach adulthood, no difference in the physical activity levels and the perceived quality of life were observed despite the difference in the exercise capacity.
Commentary from Dr. MC Leong (Kuala Lumpur), section editor of ACHD Journal Watch:
Fontan palliation may have improved the life expectancy and quality of life in patients with single ventricular physiology, but generally, patients do suffer from impaired exercise capacity. While exercise capacity differs from one patient to another, some Fontan patients do have exercise capacity comparable to people with normal biventricular hearts or even better. They are the so-called “Super-Fontans”. Higher exercise capacity in patients is associated with a better prognosis. In this study, the authors aimed to characterize factors associated with these “Super-Fontan” phenotypes.
Patients in the Australian and New Zealand Fontan Registry with cardiopulmonary exercise tests (CPET) were identified. Patients were considered “Super-Fontan” if they achieve a normal exercise and work capacity (>80% predicted). Conversely, if they achieve an exercise or work capacity < 80%, they were assigned to the control group. The ratio between Super-Fontan and control in the study was 1:3 (n=15 vs n=45). All these patients underwent the following tests for comparison: (a) exercise self-efficacy (assessment of an individual belief in their ability to continue exercising) and health-related quality of life; (b) CPET and spirometry; (c) physical activity across the lifespan (a recall of sports and physical activities participated during childhood (4-12 years old), high school and early adulthood (12-21 years old) and older adulthood (>22 years old); and (d) current level of physical activity.
Compared to the control group, the Super-Fontans were associated with a lower age of Fontan procedure, morphologically left dominant ventricle and not being obese, which underscores the importance of early volume unloading with early Fontan completion, and the concerns of increased mechanical loading and risk of obstructive sleep apnea with obesity. No significant differences between groups were noted in terms of patient’s age, type of Fontan circuit, duration after Fontan completion and the presence of Fontan fenestration (Table 1). As for the CPET and lung function, peak respiratory exchange ratio, minute ventilation and heart rate reservice were significantly higher in Super-Fontans (Table 2). In addition, the Super-Fontan tended to have normal lung function compared to controls (Table 3). Super-Fontans were noted to have higher hours per week of sports in most of their lifespan (Figure 1). However, the higher exercise capacity did not translate to a statistical significance in health-related quality of life during adulthood. In terms of the current physical activity levels, no statistical difference was noted between the Super-Fontan and control (Figure 2) which showed a slowing down of physical activity as one ages or starts his/her working life and that the benefit of higher exercise capacity is not as obvious as it were during childhood and young adulthood.
Although small in sample size and retrospective in nature, the group should be commended for their attempt in profiling the phenotypical features of a good Fontan. It encourages healthcare workers to promote a healthy lifestyle in patients with Fontan circuit eg. living an active lifestyle, maintaining ideal body weight, avoidance of cigarette smoking and the prevention of respiratory infections which may affect the lung functions of patients. Such a study is also useful in guiding risk stratification of patients and resource allocation.
