Patients after Fontan are at risk for suboptimal functional health status, and associations with laboratory measures are important for planning interventions and outcome measures for clinical trials.
Methods and Results
Parents completed the generic Child Health Questionnaire (CHQ) for 511 Fontan Cross-Sectional Study patients aged 6–18 years (61% male). Associations of CHQ Physical and Psychosocial Functioning Summary Scores (FSS) with standardized measurements from prospective exercise testing, echocardiography, magnetic resonance imaging (MRI), and measurement of brain natriuretic peptide (BNP) were determined by regression analyses. For exercise variables for maximal effort patients only, the final model showed higher Physical FSS was associated only with higher maximum work rate, accounting for 9% of variation in Physical FSS. For echocardiography, lower Tei index (particularly for patients with extracardiac lateral tunnel connections), lower indexed end-systolic volume, and the absence of atrioventricular valve regurgitation for patients having Fontan at age <2 years were associated with higher Physical FSS, accounting for 14% of variation in Physical FSS. For MRI, lower mass to end-diastolic volume ratio, and mid-quartiles of indexed end-systolic volume (non-linear) were associated with higher Physical FSS, accounting for 11% of variation. Lower BNP was significantly but weakly associated with higher Physical FSS (1% of variation). Significant associations for Psychosocial FSS with laboratory measures were fewer and weaker than for Physical FSS.
In relatively healthy Fontan patients, laboratory measures account for a small proportion of the variation in functional health status and, therefore, may not be optimal surrogate endpoints for trials of therapeutic interventions.
Keywords: Fontan procedure, heart defects, congenital, pediatrics