SESSION TITLE: Pulmonary Vascular Disease Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: October 18-21, 2020 PURPOSE: Pulmonary artery aneurysm (PAA) is defined as a main pulmonary artery (PA) diameter greater than 40 mm. It is seen in up to 20% of patients with Pulmonary Arterial Hypertension (PAH). Uncertainty remains regarding the predictive factors for the development of PAA in PAH patients as well as the characteristics of this subgroup of patients. We describe a retrospective cohort of patients to help address these knowledge gaps. METHODS: Data collection of patients in the Pulmonary Hypertension clinic at Keck Medical Center from January 2010 to January 2020 was conducted. Patient demographics and PAH etiology information was collected from clinical documentation. Additional data regarding functional status and hemodynamics was also collected. Patients were described as having Pulmonary Artery Aneurysms if their CT report described a main PA size greater than or equal to 40 mm. Univariate analysis was performed to identify variables correlating with the presence of PAA. RESULTS: A total of 473 patients were identified in the cohort of patients being treated in the PH clinic. Of these patients, 331 had a CT chest completed throughout their course. 68 patients were noted to have PAA during their follow-up period. Congenital heart disease (CHD) was the etiology of PAH most strongly associated with PAA (OR 3.61) while PAH secondary to connective tissue disease (CTD) was found to be negatively associated with the development of PAA (OR 0.29). Other etiologies of PAH were not found to significantly affect the prevalence of PAA. Patients with moderate and severe right ventricular (RV) dysfunction were more likely to have PAA (OR 2.10 and 2.16 respectively). The same was observed for severe RV dilation (OR 2.66). Higher values of mean pulmonary artery pressure (mPAP) as well as higher pulmonary vascular resistance (PVR) on initial testing were associated with the development of PAA (OR 1.05 and 1.15 respectively). CONCLUSIONS: PAA development in PAH has been previously associated with the duration of the disease. This might explain the positive association between PAA and PAH secondary to CHD, since these patients tend to have a more prolonged course of their disease, often from a young age. It was also noted that CTD was associated with lower rates of development of PAA. This may indicate that structural changes to the pulmonary artery wall caused by CTD protect against the development of PAA. The positive association between worse hemodynamic and echocardiographic parameters and the development of PAA suggests long standing increased stress on the pulmonary artery wall may contribute to the development of PAA. CLINICAL IMPLICATIONS: Understanding the factors that may contribute to the development of PAA may allow for early identification of PAH patients at risk of developing PAA and subsequent PAA-related complications. DISCLOSURES: No relevant relationships by Tiffany Chang, source=Web Response No relevant relationships by Lucas Cruz, source=Web Response No relevant relationships by Jared Geibig, source=Web Response No relevant relationships by Moses Koo, source=Web Response No relevant relationships by Ashil Panchal, source=Web Response Speaker/Speaker's Bureau relationship with Actelion, United therapeutic, and Bayer Please note: $20001 - $100000 Added 05/30/2020 by Bassam Yaghmour, source=Web Response, value=Honoraria