Effects of Riociguat on RIght VEntricular Size and Function in PAH and CTEPH

Right heart size and function are of utmost prognostic importance in PAH/CTEPH. RV performance measured by echocardiography and enlarged RA area have been shown to be independent prognostic factors in PAH. Recently, a retrospective single centre study has shown that riociguat treatment was associated with a significant reduction of RV and RA area after 3, 6 and 12 months compared to baseline. RA area significantly decreased after 12 months and RV systolic function assessed with tricuspid annular plane systolic excursion (TAPSE) improved after 6 and 12 months of riociguat therapy. The results were confirmed by a recent retrospective multicentre study. It is therefore reasonable to assume a beneficial effect of riociguat on right heart size and function. The primary efficacy endpoint in this study is the change in RV and RA area from baseline to 24 weeks. Treatment will be initiated and individually adjusted according to systolic blood pressure and tolerability. Patients who discontinue medication prematurely will be asked to continue with study assessments and perform study visits as outlined in the protocol. Medical examinations comprise medical history, physical examination, electrocardiogram (ECG), blood gas analyses, lung function tests, laboratory testing (including NT-proBNP), echocardiography at rest, and right heart catheterization (RHC) according to clinical practice of the PH centre. The prospective period of data collection comprises a 24-week study period a follow-up phase of about 30±7 days. Outcome (survival and transplant-free survival) of all patients will be assessed when the last patient has terminated his/her 24-week observation period.