Early Correlates of High-Risk Lymphatic Subtype on T2-Weighted Pre-fontan Cardiac MRI and Associated Clinical Outcomes

Lymphatic dysfunction is a severe complication of the Fontan circulation. Type 3 and 4 lymphatic subtypes identified on T2-weighted cardiac MRI (CMR) are associated with worse Fontan outcomes. Correlates of lymphatic subtype are incompletely described. Of the 171 patients with single ventricle physiology who underwent pre-Fontan CMR with T2-weighting to define lymphatic subtype between 2017 and 2021, 148 had standard-risk lymphatics (subtypes 1, 2, and 3 without pre-Fontan chylous effusions), and 23 had high-risk lymphatics (subtypes 3 with a history of pre-Fontan chylous effusions and 4). The two groups did not differ by demographic, anatomic, or pre-Fontan surgical features. High-risk subtype patients had more pre-fontan hospital days (84 vs. 44, p < 0.001), worse atrioventricular valve regurgitation (AVVR) by echocardiogram, higher aortopulmonary collateral (APC) burden (38% vs. 30%, p = 0.004) and Qp: Qs (1.2 vs. 1.05, p = 0.01) by CMR, and higher left pulmonary artery pressure (11mmHg vs. 10mmHg, p = 0.04) and higher systemic ventricular end diastolic pressure (8mmHg vs. 7mmHg, p = 0.02) by cardiac catheterization. High-risk patients were more frequently deemed to be unsuitable for Fontan palliation (22% vs. 4%, p = < 0.001) while those who did undergo palliation had longer post-Fontan length of stay (14 days vs. 9 days, p = 0.01) and more post-fontan chest tube days (10.5 vs. 7, p = 0.002). This study demonstrates a link between pre-Fontan clinical factors and lymphatic subtype. Further work is needed to understand whether modification of these risk factors might impact lymphatic anatomy.