FRI0376 Differences in right ventricular function and morphology in SSC-PAH and IPAH assessed by right heart catheterization and cardiac MRI

Background Systemic sclerosis (SSc) is a serious disorder with high mortality, mainly driven by cardiopulmonary pathologies including pulmonary arterial hypertension (PAH). Patients with SSc-PAH appear to have worse prognosis than idiopathic PAH (iPAH). Objectives (A)Compare cardiac magnetic resonance (CMR) of the right ventricle, hemodynamic parameters and immunological markers between patient cohorts with SSc-PAH, iPAH and SSc without PAH, respectively. (B)Evaluate the impact of these variables on PAH-related morbidity and mortality. Methods The study cohort included SSc-PAH (n=16), iPAH (n=15) and SSc without PAH (n=20). At baseline, all patients were examined by ventricular volumes by short axis summation of cine CMR, echocardiography and right heart catheterization (RHC). Blood samples were analysed for immune-related factors. At a median follow up of 3 years, clinical data, and new onset of PAH and vital status were registered. A composite outcome for PAH related events was created including: PAH progression, end-stage PAH, hospitalization for PAH worsening and all-cause mortality. Associations between parameters were assessed using ANOVA, Pearson Chi-square, Fishers exact, or independent sample t-test. Results Patients with SSc-PAH were significantly older at PAH onset, had lower 6MWD, DLCO% and Hb than the iPAH patients. RHC results are shown in Table 1. CMR showed that SSc-PAH patients had lower right ventricular mass index (RVMI), RV to left ventricular ratio and RV mass to volume ratio (Table 1). Multiplex immune assays demonstrated higher serum levels of IP-10, VEGF and, IL12 in SSc-PAH than in iPAH. At the end of the study, 12/15 SSc-PAH had developed a PAH-related event. Compared to event-free patients, they were marked by significant CMR changes including higher RVM (p=0.006) and RVMI (p=0.005). In the iPAH subgroup, 7/16 patients developed an event. These patients were characterized by younger age at onset (p=0.001), higher NT-proBNP (p=0.017), lower 6MWD (p=0.034), higher RVM (p=0.010), RVMI (p=0.005), RV-to-LV ratio (p=0.001) on CMR. Conclusions The CMR measures indicate that the RV adapts differently in iPAH and SSc-PAH; with more pronounced RV hypertrophy in iPAH patients. The mechanisms behind the differences in RV hypertrophy in SSc-PAH and iPAH are not known, but may involve microvascular changes and deregulated inflammatory cascades. This study indicates that CMR may predict PAH progression in SSc. Disclosure of Interest None declared