Treatment with macitentan improved right ventricular (RV) function and structure as well as cardiopulmonary hemodynamics in patients with pulmonary arterial hypertension (PAH).

These were the main conclusions of the Right vEntricular remodeling in Pulmonary ArterIal hypeRtension (REPAIR) study, recently published in the Journal of the American College of Cardiology (JACC): Cardiovascular Imaging.

“At a prespecified interim analysis in 42 patients, both primary endpoints were met, enrollment was stopped, and the study was declared positive,” the authors wrote. The primary endpoints were changes from baseline to week 26 in RV stroke volume and pulmonary vascular resistance.

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Final analysis of the effect of macitentan on RV and hemodynamic outcomes in patients with PAH (n=71) showed an increase of 12 mL (96% confidence level, 8.4-15.6 mL, P <.0001) in RV stroke volume, and a decrease of 38% (99% confidence level, 31%-44%, P <.0001) in pulmonary vascular resistance.

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RV stroke volume was evaluated by cardiac magnetic resonance (CMR).

“CMR is regarded as the most accurate noninvasive method for assessing RV function and remodeling and CMR measures of RV function and structure are strongly prognostic for survival in patients with PAH,” the authors explained. Even though, it is not a common choice when selecting methods for PAH clinical trials. Pulmonary vascular resistance was determined by right heart catheterization.

In addition, the authors observed positive changes in secondary and exploratory CMR (RV and left ventricular), hemodynamic, and functional endpoints. The improvements registered in RV, left ventricular variables, and functional parameters remained significant at a week 52 assessment.

Safety data were consistent with previous clinical trials. Among the 87 patients that comprised the safety set, 75 reported at least 1 adverse event (AE) and 14 reported at least 1 severe adverse event (SAE). Peripheral edema (n=19, 21.8%) and headache (n=18, 20.7%) were the most frequent AEs.

Ten patients discontinued macitentan treatment during the study. Among the reasons were death (n=1, a fatal SAE of cardiac arrest), meeting prespecified discontinuation criteria (n=3), physician’s decision (n=3), and patient’s decision (n=3).


Anton VN, Richard C, Emmanuelle C, et al. The REPAIR study: effects of macitentan on RV structure and function in pulmonary arterial hypertension. JACC Cardiovasc Imaging. Published online November 17, 2021. doi:10.1016/j.jcmg.2021.07.027