The unique clinical phenotype and exercise adaptation of Fontan patients with normal exercise capacity

ABSTRACT Background Exercise limitation is almost universal among Fontan patients. Identifying unique clinical features in the small fraction of Fontan patients with normal exercise capacity (high capacity Fontan, HCF) provides potential to inform clinical strategies for those with low exercise capacity (usual Fontan, UF). Methods We performed a retrospective chart review of all single ventricle patients palliated with a Fontan operation who underwent incremental cardiopulmonary exercise testing at Cincinnati Children’s Hospital Medical Center from 2013-2018. Comparison was between patients with peak oxygen uptake (VO2peak) > 80% predicted. Results Twenty two of 112 patients were classified as HCF (68% female; 18±7 years). During incremental exercise, VO2peak (86.1±6.1% vs 62±12.2 % predicted; p > 4 days/week for at least 30 minutes (77% vs 10%, p Conclusions Approximately 1 in 5 Fontan patients who undergo cardiopulmonary exercise testing have normal exercise capacity despite chronotropic impairment. This implies a better preserved stroke volume, perhaps due to greater muscle pump-mediated preload. Additionally, a complicated perioperative Fontan course is associated with eventual impaired functional capacity.