BACKGROUND. Right-sided heart failure is the leading cause of death in pulmonary arterial hypertension (PAH). Similar to left heart failure, sympathetic overactivation and β-adrenoreceptor (βAR) abnormalities are found in PAH. Based on successful therapy of left heart failure with β-blockade, the safety and benefits of the nonselective β-blocker/vasodilator carvedilol were evaluated in PAH. METHODS. PAH Treatment with Carvedilol for Heart Failure (PAHTCH) is a single-center, double-blind, randomized, controlled trial. Following 1-week run-in, 30 participants were randomized to 1 of 3 arms for 24 weeks: placebo, low-fixed-dose, or dose-escalating carvedilol. Outcomes included clinical measures and mechanistic biomarkers. RESULTS. Decreases in heart rate and blood pressure with carvedilol were well tolerated; heart rate correlated with carvedilol dose. Carvedilol-treated groups had no decrease in exercise capacity measured by 6-minute walk, but had lower heart rates at peak and after exercise, and faster heart rate recovery. Dose-escalating carvedilol was associated with reduction in right ventricular (RV) glycolytic rate and increase in βAR levels. There was no evidence of RV functional deterioration; rather, cardiac output was maintained. CONCLUSIONS. Carvedilol is likely safe in PAH over 6 months of therapy and has clinical and mechanistic benefits associated with improved outcomes. The data provide support for longer and larger studies to establish guidelines for use of β-blockers in PAH. TRIAL REGISTRATION. ClinicalTrials.gov NCT01586156 FUNDING. This project was supported by NIH R01HL115008 and R01HL60917 and in part by the National Center for Advancing Translational Sciences, UL1TR000439.
Samar Farha, Didem Saygin, Margaret M. Park, Hoi I. Cheong, Kewal Asosingh, Suzy A.A. Comhair, Olivia R. Stephens, Emir C. Roach, Jacqueline Sharp, Kristin B. Highland, Frank P. DiFilippo, Donald R. Neumann, W.H. Wilson Tang, Serpil C. Erzurum
Differences in biological outcomes measured among the 3 study groups at baseline, 1-month, 3-month, and 6-month visits