(RIGHT HEART III Study - Right Ventricular Hemodynamic Evaluation and Response to Treatment)

In this multi-center, randomized, open pilot study the therapeutic effect of two prarallel groups treated with either Riciguat or Macitentan shall be determined by evaluating the change in systolic and diastolic RV function within 12 weeks after first drug intake in order to plan a larger Phase II study.The method used to determine the RV function will be the "Conductance Method".

Inclusion criteria

• Female and male patients, 18 years ≤ age ≤ 85 years
• Diagnosis of Pulmonary Hypertension Group 1 according to Nizza Definition (PAH) confirmed by invasive methods, WHO functional class II and III
• Existing clinical need to repeat a right ventricular catheter examination (as recommended by the current "Kölner Konsensuskonferenz")
• Ability to understand study goals and agree to study participation
• Hemodynamic criteria of ventricular catheter examination:

• Pulmonary vascular resistance (PVR)> 240 dyn x sec x cm-5
• Mean Pulmonary Arterial Pressure (mPAP) ≥ 25 mmHg
• Clinical need to receive treatment with a drug approved for the treatment of PAH for the first time
• Potentially fertile women must agree to use highly effective methods of contraception, either through abstinence or the use of at least two methods of contraception from the date of consent until one month after the end of the study. An effective pregnancy protection consists in the combination of a hormonal contraceptive (oral, injectable or implant) and a barrier method (condom or diaphragm with a vaginal spermicide)
• Written consent to the clinical trial

Exclusion criteria

Existing therapy with positive inotropic drugs such as Catecholamines (including norepinephrine, dobutamine, suprarenin)

• Pregnancy or breastfeeding
• General contraindication for examinations to be performed during the study
• Hypersensitivity to the active substances or to a constituent of the study medication (in particular lactose and soya)
• Simultaneous participation in another medical therapy study
• Simultaneous participation in another non-drug study that would preclude participation in this study
• Participation within one month after completing another therapy study
• Heavy liver function disorders
• Existing increase in liver aminotransferases (aspartate aminotransferase (AST) and / or alanine aminotransferase (ALT))> 3 × ULN
• Systolic blood pressure <95 mmHg
• Pulmonary hypertension associated with idiopathic interstitial pneumonia (PH-IIP)
• anemia (Hb <10 g / dl)
• Concomitant medication with potential interaction to macitentan and/or riociguat according to the IB
• Severe kidney dysfunction
• Severe hemoptysis
• History of bronchial artery embolization
• smoker