Most patients with Fontan circulation struggle to increase cardiac output during exercise affecting aerobic capacity, response to training and quality of life. This poor cardiac performance affects their aerobic capacity, their response to training and their quality of life. We sought to identify the pre-Fontan and managerial factors that influence their exercise cardiac performance.

We retrospectively collected pre and post-Fontan anatomical, anamnestic and hemodynamic data in 57 consecutive young Fontan patients (median age 14.7 years) who underwent cardiopulmonary exercise test. We studied their exercise cardiac performance using a thoracic bioelectrical impedance device that allows measurement of the peak cardiac index (pCI).

The median age at Fontan was 6.4±3 years. In multivariable models, pCI was negatively influenced by cyanosis duration (B=−0.240; P=0.0002). Peak indexed stroke volume (pSVi) was negatively influenced by Norwood procedure (B=-8.415; P=0.005) and cyanosis duration (B=−1.591; P=0.0002) and peak heart rate (pHR) by pre-Fontan peripheral oxygen saturation (B=0.602 P=0.009). Cyanosis duration≤6.9 years predicted a pSVi≥45 mL/m2 (AUC=0.747; P=0.001). Furthermore, pSVi and pHR were correlated with post-Fontan ventricular filling pressure (post-VFP) (respectively rp=−0.539, p=0.012 and rp=−0.552; P=0.010) and post-VFP was correlated with bidirectional cavopulmonary shunt duration (rs=0.498, P=0.023).

In young Fontan patients, the duration of cyanosis and low peripheral oxygen saturation prior to the Fontan procedure affect both components of cardiac exercise performance probably through increased ventricular filling pressure. Shortening the duration of cyanosis could help preserve cardiac performance in the long term.