Assessment of exercise capacity using field walking tests in patients after the Fontan procedure: A case-control study

Background: Despite the frequent use of the 6-minute walk test (6MWT), exercise capacity has not been assessed with the incremental shuttle walk test (ISWT) in patients who have undergone the Fontan proce-dure. It is unclear whether these tests cause clinically relevant cardiorespiratory responses in these patients.Objectives: We aimed to assess cardiorespiratory responses to the 6MWT and ISWT in Fontan patients, com-pare the responses with those in the controls, and examine the agreement between the two field tests. Methods: Submaximal exercise capacity was assessed using the 6MWT, maximal exercise capacity using the ISWT, quadriceps isometric muscle strength with a hand dynamometer, and body composition using a bio-electrical impedance device. Results: Twenty-one Fontan patients (16.42 +/- 6.63 years, 5F/16M) and 21 controls (16.57 +/- 4.30 years, 7F/14M) were included. While body composition was similar between the groups (p>0.05), quadriceps isometric muscle strength and 6MWT and ISWT distance were lower in the Fontan patients than in the controls (p<0.05). In both the 6MWT and ISWT, pre-and post-test heart rate (HR), oxygen saturation (SpO2), dyspnea, and leg fatigue differed significantly between the Fontan patients and the controls (p<0.05). In addition, the ISWT resulted in a more significant change in HR, SpO2, and leg fatigue than the 6MWT in the Fontan patients (p<0.05). Bland-Altman plots for the 6MWT vs. the ISWT indicated agreement between the two tests. Conclusion: There were remarkable changes in HR, SpO2, dyspnea, and leg fatigue in both tests. With similar safety to the 6MWT but with more caution applied for adverse events, the ISWT can also be performed as a field test to evaluate exercise capacity and identify more pronounced exercise-induced responses (especially oxygen desaturation) in Fontan patients. (c) 2023 Elsevier Inc. All rights reserved.

Automated summary

Cardiorespiratory responses were assessed in Fontan patients using the 6-minute walk test (6MWT) and incremental shuttle walk test (ISWT). It was found that both tests showed significant changes in heart rate, oxygen saturation, dyspnea, and leg fatigue. The ISWT, which is safer and provides more pronounced exercise-induced responses, can be used as a field test to evaluate exercise capacity in Fontan patients.