Exercise capacity and muscle strength in patients who have undergone the Fontan procedure: a retrospective follow-up study

Background. Due to their relationship with clinical progression, follow-up of exercise capacity and muscle strength is important for optimal disease management in patients who have undergone the Fontan procedure. We aimed to retrospectively analyze exercise capacity and muscle strength trajectory over approximately 2 years. Methods. Exercise capacity was assessed using an exercise stress test with the modified Bruce protocol on a treadmill, hand grip and knee extensor strength using a hand dynamometer, and body composition using a bioelectrical impedance device. Exercise capacity, muscle strength, and body composition follow-up data recorded between 2020 and 2022 were compared. Results. Fifteen patients [median age from 17 (first assessment) to 18 years (last assessment), 5 females)] with a 20 -month median follow-up time were analyzed retrospectively. There was an increase in weight, height, body mass index, and body fat weight (p<0.05). There was a tendency for increased handgrip strength (%) (p=0.069), but no significant difference was observed in the knee extensor strength of patients during the follow-up period (p>0.05). The changes in heart rate (HR) and oxygen saturation were higher in the last test than in the first test (p<0.05). Maximum HR (HRmax), % predicted HRmax and HR reserve recorded during the test and HR 1 minute after the test were similar between the first and last tests (p>0.05). Conclusions. After 20 months of follow-up, exercise capacity and muscle strength did not decline; instead, the body mass index and fat weight increased. Patients who have undergone the Fontan procedure may not be experiencing a decline in exercise capacity and muscle strength over relatively short time periods during childhood, adolescence, and early adulthood.