Diagnostic value of the six-minute walk test (6MWT) in grown-up congenital heart disease (GUCH): Comparison with clinical status and functional exercise capacity

BackgroundExercise testing for the assessment of functional capacity plays an important role in long-term follow-up of GUCH patients. CPX is the favored modality for decision-making recommended in the current guidelines. In contrast to this complex method, the 6MWT is a simple, easy-to-perform, safe, and commonly available exercise test. Although well-established in various cardiopulmonary diseases, the diagnostic impact of the 6MWT in GUCH patients is not known so far.Methods102 GUCH patients were evaluated by 6MWT and CPX simultaneously. Clinical symptoms were assessed, according to the NYHA classification. Additionally, an echocardiography study, and selected cardiac blood tests (N-terminal pro-brain natriuretic peptide (NT-proBNP), high-sensitive Troponin T) were performed.ResultsRanges of six-minute walk distance (6MWD) and peak oxygen consumption (peakVO2) were 116-765 m and 6.4-36.2 ml/kg/min, respectively. 6MWD and peakVO2 showed a close correlation (r = 0.72, 95% CI, 0.63 to 0.79). Patients with a peakVO2 of ≤ 15.5 ml/kg/min were excellently identified by 6MWT (c-value = 0.82). A cut-off value of 482 m was optimal to predict reduced peakVO2. In multivariate regression analysis, 6MWD and NYHA class were identified as relevant predictors of peakVO2. In subgroup analysis, Eisenmenger patients achieved the shortest 6MWD (280, SD 178 m).ConclusionIn our study population of GUCH patients, the 6MWD shows a close correlation to peakVO2, and an excellent prediction of reduced peakVO2. Thus, it seems to be an easy-to-perform and reliable screening parameter to evaluate functional capacity of these patients (Controlled Clinical Trials number, NCT02193243).