Table 2 Patient eligibility criteria

1. Female and male patients ≥ 18 years

2. WHO functional classes II–IV

3. PH confirmed by RHC, showing mPAP > 20 mmHg at rest; HF confirmed by invasive measurements, when mPAWP ≥ 15 mmHg or LVEDP ≥ 16 mmHg at rest and/or PAWP ≥ 25 mmHg during exercise and/or PAWP > 18 mmHg after the fluid challenge test

4. Preserved left ventricular ejection fraction > 50% (measured by echocardiography or MRI)

5. A patient received optimized and for ≥ 1 month stable therapy, including adequate treatment with diuretics

6. Except for diuretics, medical treatment should not be expected to change during the study period

7. Able to understand and willing to sign the informed consent form

1. Pre-capillary pulmonary hypertension (group I, group III, group IV, group V, according to the ESC/ERS PH guidelines)

2. Congenital or acquired severe valvular diseases (severe aortic stenosis or insufficiency, severe mitral valve stenosis or insufficiency)

3. Active myocarditis, unstable angina pectoris, exercise-induced ventricular arrhythmias, active liver disease, porphyria, or elevations of serum transaminases > 3 × ULN (upper limit of normal) or bilirubin > 1.5 × ULN

4. Severe lung disease: FEV1/FVC < 0.5 and total lung capacity < 60% of the normal value

5. A subject who participates in an interventional study during this study

6. Walking disability or other orthopedic limitations to exercise

7. Hemoglobin concentration less than 75% of the lower limit of normal

8. Systolic blood pressure < 85 mmHg

9. Pregnancy or lactation

10. History or suspicion of inability to cooperate adequately