The REPAIR Study: Effects of Macitentan on RV Structure and Function in Pulmonary Arterial Hypertension

Area of Science:

• Cardiology
• Pulmonology
• Pharmacology

Background:

• Right ventricular (RV) failure is a major cause of mortality in pulmonary arterial hypertension (PAH).
• Cardiac magnetic resonance (CMR) is a highly accurate noninvasive tool for assessing RV function and structure, with prognostic value in PAH.
• CMR is underutilized in clinical trials for PAH.

Purpose of the Study:

• To evaluate the effect of macitentan on RV remodeling and hemodynamics in patients with PAH.
• To assess changes in RV stroke volume and pulmonary vascular resistance using CMR and right heart catheterization (RHC).

Main Methods:

• The REPAIR study was a 52-week, open-label, phase 4 trial involving patients with PAH.
• Macitentan (10 mg) was administered, with or without PDE-5 inhibitors.
• Primary endpoints included changes in RV stroke volume (CMR) and pulmonary vascular resistance (RHC) at 26 weeks.

Main Results:

• At 26 weeks, RV stroke volume increased by 12 mL (P < 0.0001) and pulmonary vascular resistance decreased by 38% (P < 0.0001).
• Significant improvements were observed in secondary CMR, hemodynamic, and functional endpoints.
• These improvements in RV and left ventricular function were maintained at 52 weeks.

Conclusions:

• Macitentan treatment led to significant and clinically relevant improvements in RV function, structure, and hemodynamics in PAH patients.
• The observed benefits on RV function and structure were sustained throughout the 52-week study period.