Decline Is Not Inevitable: Exercise Capacity Trajectory in an Australian and New Zealand Fontan Cohort

In people with a Fontan circulation, serial cardiopulmonary exercise testing (CPET) to evaluate change in peak exercise capacity has been increasingly recognised as a useful prognostic tool; a decline is associated with adverse clinical outcomes. The aim of this study is to describe the "natural" history of exercise capacity in the Australian and New Zealand (ANZ) Fontan cohort and to identify factors associated with a decline.

The ANZ Fontan registry was retrospectively reviewed for adolescent and adult patients (≥16 years) with serial CPET results performed on a cycle ergometer ≥6 months apart. Patients were excluded if they underwent a surgical procedure or fenestration closure in-between tests or if the tests were considered as submaximal effort. Exercise capacity trajectory was defined as the change in percentage of predicted peak oxygen uptake (% pred VO_2peak) points per year.

Thirty-seven (37) patients (59.5% male, mean age 24±7 years) were eligible. Average duration between CPET was 5.3±3.9 years. At baseline, % pred VO_2peak was 61.3±14.5%. Thirteen (13) (35%) had a systemic right ventricle, and 14 (38%) had an atriopulmonary type Fontan circulation. Average change in % pred VO_2peak overall was +1.3±6.4 percentage points per year. Sixteen (16) had a negative exercise capacity trajectory, and the average decline in that group was -2.7±3.4 percentage points per year. There was no association between exercise capacity trajectory and clinical characteristics. Of the 18 patients with physical activity levels recorded, 12 (67%) were physically active and % pred VO_2peak in that group increased by 2.7±4.0 percentage points per year compared with the physically inactive group who fell by 0.5±0.8 percentage points per year.

In this ANZ series of Fontan patients, over half of our cohort had stable, or an increase, in peak exercise capacity. Regular participation in physical activity was common in patients with a positive exercise capacity trajectory. Clinical characteristics were not associated with exercise capacity trajectory.