Abstract 9672: Older Age at Fontan is Associated with Improved Exercise Performance in the Current Era

Abstract

Introduction: Exercise capacity is associated with mortality and morbidity in Fontan patients. Debate continues about modifiable factors impacting exercise. Hypothesis: We assessed the hypothesis that later Fontan completion and larger branch pulmonary arteries are associated with better exercise. Methods: We performed a retrospective review of exercise stress test (EST) data from 2003 to 2011 in Fontan patients undergoing the Bruce protocol. The primary marker of performance was percent of predicted maximum oxygen consumption (%MVO 2 ). Pulmonary artery caliber was assessed using tomographic or angiographic imaging, and included if imaging was performed four years before or after the EST. Imaging or catheterization data were excluded if surgical or catheterization based interventions were performed such that a patient's anatomy changed between the time of EST and imaging. Analysis was performed on the entire cohort and a Current Era group defined as patients who underwent Glenn ≤ 1 year, did not have a pacemaker at EST, and achieved a respiratory exchange ratio ≥1.0. Results: During the study period, 144 patients were identified (mean age 13.7 ± 5.3 years). Among Current Era patients (n = 55), both older age at Fontan (R = 0.286, p = 0.034) and Nakata index (R = 0.389, p = 0.049) were positively associated with %MVO 2 . There were negative associations between time from Fontan to EST (R = -0.367, p = 0.006) and Fontan pressure (R = -0.501, p = 0.015). For the entire cohort, longer time from Fontan to EST (R = -0.461, p < 0.001) and higher Fontan pressure (R = -0.271, p = 0.046) were associated with diminished performance. In both groups, multivariable regression was performed for variables that were significantly correlated ( p < 0.05) with %MVO 2 . Time from Fontan to EST was significant for Current Era patients (slope coefficient -3.2, p = 0.010) and the entire cohort (slope coefficient -1.6, p = 0.005). Conclusion: Older age at Fontan after Glenn and shorter time from Fontan to EST are associated with higher %MVO 2 , suggesting that Fontan completion should be delayed in the current era. Smaller Nakata index and elevated Fontan pressure negatively correlate with %MVO 2 , providing a rationale for intervening on stenotic pulmonary arteries.