Abstract 4362057: The Impact of Novel Lymphatic Interventions on Short- and Long-Term Outcomes of Chylothorax Following Pediatric Cardiac Surgery

Background: Chylothorax is as a complex disorder of abnormal lymphatic flow. Single ventricle (SV) patients are more susceptible due to altered venous and lymphatic pressures with staged palliation. MR lymphangiography has identified pulmonary lymphatic perfusion syndrome (PLPS) as the most common etiology with favorable response to lymphatic percutaneous interventions such as nonselective TD embolization (TDE) or selective lymphatic duct embolization (SLDE). However, comparative studies between TDE and SLDE for post-operative chylothorax remain limited. We hypothesize that patients who receive SLDE have shorter time to reach chest tube output < 5 mL/kg/d (chylothorax resolution) and lower risk of developing new lymphatic abnormalities compared to those who had TDE. Methods: Single-center retrospective study of congenital heart disease (CHD) patients with post-operative chylothorax who had lymphatic imaging and intervention between 7/2012-11/2023. Those who did not undergo lymphatic intervention were excluded. Exposure was defined by first intervention type. Outcomes included resolution of chylothorax, time to resolution and new onset of other lymphatic abnormalities. Results were stratified by ventricular status Results: Out of 130 patients referred for lymphatic imaging due to chylothorax, 96 met inclusion criteria. SV circulation was present in 80%. Most patients had SLDE (55%). Baseline trends were attributable to the SV subgroup receiving SLDE, who were older and more likely to have mesenteric edema pre-intervention. PLPS was seen in 92% of patients. Rates and time to chylothorax resolution were similar (94% and median 5 days, respectively). There were 16 patients who developed new lymphatic abnormality after the initial lymphatic procedure. Of those, 10 had TDE, 4 SLDE with TD occlusion seen on follow-up imaging, and 2 had SLDE (one with hepatopulmonary connections). In follow-up, a total of 52 patients had TD occlusion (43 TDE, 6 SLDE with unintended TDE and 3 SLDE followed by TDE). In this group, 29% of patients developed new onset lymphatic abnormalities compared to 4% in the SLDE only group (p=0.002). Postprocedural complication rates were similar. Conclusion: This is the largest single-center study demonstrating an excellent response of lymphatic intervention for post-operative chylothorax. While there were no differences in short-term rates of resolution, maintaining TD patency is critical to preventing future lymphatic abnormalities and complications