On Monday, Merck & Co Inc MRK revealed topline results from the Phase 3 ZENITH study evaluating Winrevair (sotatercept-csrk) in adults with pulmonary arterial hypertension (PAH, WHO Group 1) functional class (FC) III or IV at high risk of mortality.PAH is high blood pressure in pulmonary arteries, which carry oxygen-poor blood from the heart to the lungs.ZENITH met its primary endpoint of time to first morbidity or mortality event (all-cause death, lung transplantation, or PAH worsening-related hospitalizat ...