Carvedilol PAH A Pilot Study of Efficacy and Safety

This is a prospective, open label, uncontrolled, pilot study examining the safety and efficacy of beta-blocker therapy with carvedilol on RV function in stable PAH Patients with World Health Organization (WHO) functional class II or III symptoms and RV ejection fraction (EF) \< 40%. Twenty-five evaluable patients will be enrolled at the University of Minnesota. Specific Aims: 1.1 Primary Efficacy Endpoint: Adult males and females on a stable dose of an approved PAH medication will undergo cardiac magnetic resonance imaging (MRI), right heart catheterization (RHC), echocardiogram, 6-minute walk test (6-MWT), measurement of plasma NT-ProBNP and serum catecholamine, and quality of life assessment. Patients will receive carvedilol (3.25 mg/kg bid escalating to 25 mg/kg bid over 3 months). Testing is repeated at the end of the study (month 6). RVEF measured by cardiac MRI is the primary efficacy endpoint. We define a 5% increase in RVEF as a meaningful change.