TOPIC: Cardiovascular Disease TYPE: Medical Student/Resident Case Reports INTRODUCTION: PAH is diagnosed when mean pulmonary artery pressure is greater or equal to 20 mmHg at rest with a pulmonary vascular resistance =3 Wood units. In regions without endemic schistosomiasis, it is commonly idiopathic (1). Eisenmenger syndrome (ES) is the most advanced form of pulmonary arterial hypertension (PAH) and is associated with several congenital heart defects such as ASDS, VSDS etc. CASE PRESENTATION: We present the case of a 30-year-old patient with a past medical history of Trisomy-21, unrestricted ventricular septal defect (VSD) complicated by Eisenmenger Syndrome, PAH (On Treprostinil and Bosentan), chronic hypoxia and Hashimoto's Thyroiditis, who presented from his group home for acute on chronic shortness of breath and fever. Initially, he was hypoxic and hypotensive with signs of severe volume overload on physical exam. Oxygen saturations improved mildly on high flow nasal cannula (HFNC). CT chest and bedside echocardiogram showed a massive pericardial effusion (4.5 cm at the largest point) with tamponade physiology, and pulsus paradoxus (Figure 1,2,3). He was started on vasopressors, inotropes, intravenous prostacyclin and inhaled epoprostenol. Extracorporeal membrane oxygen (ECMO) was planned to stabilize him and drain the effusion, but the family refused ECMO. A Swanz Ganz catheter was placed under fluoroscopic guidance to help guide management but it crossed the VSD and inadvertently ended up in the aorta after which it was removed. After multiple discussions with adult congenital heart disease experts, it was decided that draining the pericardial effusion was not an option given the concern for acute right ventricular failure which could precipitate hemodynamic collapse and cardiac arrest. Another concern was bleeding complications especially bleeding into the pericardial cavity from inadvertently puncturing the multiple collateral vessels that such patients develop. The patient gradually developed increasing vasopressor requirements and eventually passed away. DISCUSSION: A pericardial effusion develops when fluid accumulates between the two layers of pericardium. In PAH, it may develop due to elevated right atrial pressures or underlying connective tissue disease. Its presence in PAH is associated with a significantly increased risk of death and the decision to drain such an effusion remains highly controversial. Multiple studies have reported dismal prognosis of patients who have had such effusions drained (2). The Euro heart survey reported that mortality was particularly high in patients with Eisenmenger's, and they had an increased frequency of major bleeding events as well (2). CONCLUSIONS: Pericardial effusion drainage in patients with pulmonary arterial hypertension is controversial and is associated with poor outcomes. Mortality is particularly high in patients with Eisenmenger's, and a multidisciplinary approach should be utilized to manage such patients. REFERENCE #1: Simonneau G, Montani D, Celermajer DS, et al. Haemodynamic definitions and updated clinical classification of pulmonary hypertension. Eur Respir J. 2019;53(1):1801913. REFERENCE #2: Engelfriet PM, Duffels MG, Möller T, et al. Pulmonary arterial hypertension in adults born with a heart septal defect: the Euro Heart Survey on adult congenital heart disease. Heart. 2007;93(6):682-687. DISCLOSURES: No relevant relationships by Saad Farooq, source=Web Response No relevant relationships by ELLIOT SULTANIK, source=Web Response No relevant relationships by Guy Weigold, source=Web Response No relevant relationships by Omar Yacob, source=Web Response