Abstract 17257: Aortopulmonary Collateral Burden in the Fontan Circulation: Longitudinal Changes and Relationship With Clinical Outcomes

Abstract

Background: Aortopulmonary collaterals (APC) are a common source of volume load in patients with a Fontan circulation and their burden can be quantified by CMR. Longitudinal trends in APC flow and their relationship with outcomes have not been described. Hypothesis: Higher APC flow will be associated with worse clinical outcomes in Fontan patients. Aims: To assess longitudinal changes in APC flow in the Fontan circulation using CMR and their relationship with outcomes. Methods: Single-center retrospective analysis of Fontan patients who had at least 1 CMR with APC flow data. APC flow was estimated as the difference between aortic and systemic venous flows and also expressed as a percent of aortic flow. Primary outcome was a composite of death or heart transplantation; secondary outcomes included protein losing enteropathy, ascites, chylothorax, and hemoptysis. The baseline (time at Fontan=time 0) and trend in APC flow were estimated using a linear mixed model with a random intercept and slope for each patient. Results: Analysis included 758 CMRs from 356 patients; 123 of whom had ≥ 2 CMRs. Median age at first CMR was 14 y (IQR 10-19 y) and median CMRs per patient were 2 (range 1-12). Baseline APC flow was 0.6 (±0.5) L/min/m 2 or 17 (±10) % of aortic flow. Increasing APC flow over time correlated with increasing trend in ventricular dilation and decreasing trend in SaO 2 . Over a median follow-up of 17 years, 22 patients (6%) had the composite outcome. High baseline APC flow as well as an increasing trend in APC flow were associated with clinical outcomes including an independent association with death or heart transplantation (Table). Conclusions: APCs represent a significant hemodynamic burden in functional single ventricle hearts palliated to the Fontan circulation. Higher and increasing APC flow is associated with worse clinical outcomes. Factors contributing to APC development and whether APC occlusion results in a lasting reduction in the burden remain to be elucidated.