Main Inclusion Criteria:
(1) Males or females ≥ 18 years of age.
(2) Chronic heart failure fulfilling all of the following criteria:
a. Relevant structural heart disease and/or diastolic dysfunction [ESC Guidelines 2012].
b. Ejection fraction ≥ 30% measured by echocardiography.
c. New York Heart Association (NYHA) functional Class II or III.
(3) Pulmonary hypertension (PH) in WHO group 2 (Nice classification) with a pulmonary artery wedge pressure
(PAWP) of > 15 mmHg confirmed by any previous right heart catheterization (RHC).
(4) RHC within 12 weeks prior to the Screening visit or during the Screening period showing the following:
a. Mean pulmonary artery pressure (mPAP) ≥ 25 mmHg at rest.
b. PAWP or left ventricular end diastolic pressure ≤ 25 mmHg.
c. Pulmonary vascular resistance (PVR) at rest ≥ 240 dyn∙sec/cm5
d. Diastolic pulmonary vascular pressure gradient (DPG) ≥ 7 mmHg.
(5) 6-minute walk distance ≥ 150 m at Screening or Randomization.
Main exclusion criteria:
(1) PH associated with significant unrepaired structural valvular heart disease (i.e., moderate or severe aortic
stenosis, aortic insufficiency, mitral stenosis, mitral regurgitation still persisting after fluid control).
(2) Evidence of pulmonary edema; Presence of orthopnea.
(3) Presence of moderate to severe peripheral edema despite optimal diuretic therapy
(4) History of pulmonary thromboembolism with segmental defect on ventilation/perfusion scan.
(5) Systemic hypertension, i.e., systolic blood pressure (SBP) > 180 mmHg or diastolic blood pressure (DBP) > 100 mmHg; SBP < 90 mmHg; Uncontrolled heart rate from atrial fibrillation (> 100 beats per minute).
(6) Severe obstructive lung disease defined as: forced expiratory volume in 1 second / forced vital capacity (FEV1/FVC) < 0.7 associated with FEV1 < 50% of predicted value after bronchodilator administration; Known severe emphysema, e.g., total lung capacity > 120% of predicted value.
(7) Myocardial infarction within 6 months prior to Randomization.