Long-term Riociguat administration reduces right heart size in Pulmonary Arterial Hypertension and Chronic Thromboembolic Pulmonary Hypertension: a retrospective single-center analysis.
Background: Riociguat has been shown to improve exercise capacity in pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTPEH). However, the effects of Riociguat on right ventricular (RV) and right atrial (RA) size have not been assessed so far. The aim of this study was to evaluate the change of right heart size and function assessed by echocardiography and right heart catheterization in patients who received Riociguat.
Methods: We assessed patients that received Riociguat in our centre within the trials PATENT, PATENTplus, EAS and CHEST. Echocardiography including RV and RA area, TAPSE, RV wall thickness as well as 6-minute walking distance (6MWD) were assessed and analyzed at baseline, after 3, 6 and 12 months. Hemodynamics was also assessed by right heart catheterization at baseline and after 3 months. To deal with missing data, we performed two kinds of sensitivity analyses (last observation carried forward (LOCF) and baseline observation carried forward (BOCF)).
Results: Thirty-nine patients (21 PAH, 18 CTEPH, mean pulmonary arterial pressure 43 ± 2 mmHg, PVR 600 ± 43dynes*s*cm-5, Cardiac Output 4.8 ± 0.16L/min, 56.4% treatment-naïve at baseline) were included into the study. RV area significantly decreased after 3 (-2.1 ± 3.9 cm2, p = 0.002), 6 (-4.2 ± 3.2 cm2, p < 0.001) and 12 months (-5.9 ± 4.6 cm2, p < 0.001). Right atrial area significantly decreased after 12 months (-3.5 ± 4.1 cm2, p < 0.001) and TAPSE significantly improved after 6 (+2 ± 4.7, p = 0.025) and 12 months (+3.6 ± 5.4, p = 0.002). Furthermore, RV wall thickness and 6MWD significantly improved after 3, 6 and 12 months (all p < 0.05). Invasive hemodynamics significantly improved after 3 months. Both LOCF and BOCF showed identical significance and lower effect sizes.
Conclusion: Long-term Riociguat administration reduced significantly right heart size and improved RV function in this patient cohort. Further larger studies are needed to confirm these results.