Risk assessment after combination therapy in patients with CHD-PAH and Eisenmenger Syndrome in a low-middle income country

<bold>Introduction:</bold> Eisenmenger syndrome (ES) arise from a congenital heart disease-associated (CHD) with severe pulmonary arterial hypertension (PAH). Current approved therapies for PAH in low-middle income countries (LMIC) are limited with adverse outcomes. Data regarding combination therapy in patients with ES who reside in LMIC as Mexico is limited. We analyzed the risk assessment after adding an endothelin receptor antagonist (ERA’s) in patients on background therapy with phosphodiesterase type-5 (PDE5) inhibitors. <bold>Methods:</bold> This is a single-center cohort study including all patients with a confirmed diagnosis of ES due to CHD-PAH on background therapy with PDE5. All patients underwent 6-minute walk test, transthoracic echocardiogram and biomarkers at baseline and during follow-up at 18 and 52 weeks. Risk assessment was analyzed with the REVEAL Lite 2.0. The study was conducted in accordance with the Declaration of Helsinki and Ethical approval was obtained from the Institutional Ethics Committee (protocol number 2023-008). <bold>Results:</bold> 11 patients were evaluated; all were female, median age 45 years (IQR 36-51). At baseline, 91% of patients were classified as Intermediate-High Risk. At 18 weeks, 100% of patients were re-classified as low risk with no hospital admissions and significant changes in 6-MWT (p=0.035), BNP (p=0.003), Echo-PsAP (p=0.037). Unfortunately, at 52 weeks, due to the lack of continuous access to medication, 67% of patients were re-classified as Intermediate-High risk with 2 hospitalizations and 2 patients died. <bold>Conclusions:</bold> significant changes in the risk assessment were observed at 18 weeks after combination therapy, but not at 52 weeks.