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

Background: Cardiopulmonary exercise testing (CPET) provides a comprehensive objective assessment in patients with repaired Tetralogy of Fallot (rTOF). However, the evidence underpinning this practice is scanty as are the mechanisms which drive exercise ability.Objectives: To describe the current evidence linking CPET data and prognosis in addition to review the most important determinants of exercise.Methods: The preferred reporting items (PRISMA) guidelines were followed. A systematic search of CPET studies, with/without echocardiography was carried out on PubMed MEDLINE, EBM review-Cochrane Database, Wiley Online library and EBM reviews.Results: Of 400 studies identified, 21 met the inclusion criteria. 17 articles (81%) were reported in young adults, and 4 articles (19%) in younger group. The sample size ranged from 15 to 875, and the publication year ranged from 2002 to 2019. Mean age was 25 +/- 7 years. Overall mean predicted VO2 peak was 68 +/- 2.8% (95% CI. 62.3-74%). There was no difference in mean predicted VO2 between older and younger groups (68 +/- 2.7 vs 69 +/- 2.9,%, p > 0.05). Peak predicted VO2 was found to be higher in contemporary studies than historic investigations (76 +/- 6 vs 59 +/- 13,%, p.001). Submaximal measures were rarely reported. Determinants of exercise capacity were reported in 9 studies (43%). Prognostic findings qualitatively suggested that mild exercise intolerance with preserved ventilatory-equivalent for carbon dioxide is associated with better outcomes and lower mortality rate.Conclusions: The literature showed a high degree of heterogeneity which limited comparability. Marked reduction in functional capacity in patients with repaired TOF seems to be more dependent on surgical selection and developing technique than advancing age.