Clinically stable patients receiving standard HF therapy with a left ventricular ejection fraction > 50 % , mean pulmonary artery pressure ( mPAP ) 25 mm Hg , and pulmonary arterial wedge pressure ( PAWP ) > 15 mm Hg at rest were randomized to single oral doses of placebo or riociguat ( 0.5 , 1 , or 2 mg ) .