Could a natural hormone help hearts in pulmonary hypertension?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: Diagnosis of PAH that is 1) idiopathic, 2) heritable or 3) associated with connective tissue disease, congenital systemic-to-pulmonary shunt, porto-pulmonary hypertension, drug or toxin use. Documentation of the following at any time prior to study entry: * mPAP ≥ 25 mmHg at rest, pulmonary capillary wedge pressure or left ventricular end-diastolic pressure ≤ 15 mmHg, and PVR \> 3 Wood units * Pulmonary function testing documenting forced expiratory volume in one second/forced vital capacity ratio ≥ 70% predicted and total lung capacity ≥ 70% predicted * If TLC is mildly reduced (60%\<TLC%\<70%), computerized tomography (HRCT or non-HRCT) documenting no significant interstitial lung disease may be used to fulfill this requirement. * Chest tomography documenting no more than moderate parenchymal lung disease with clinician designated WHO I PAH and meeting both TLC and FEV1/FVC criteria. * Normal or low probability V/Q scan * If no V/Q scan is available, a CT angiogram documenting the absence of thromboembolic disease may be used, provided the subject meets diagnostic PAH criteria Exclusion Criteria: * Age \< 18 years old * PAH associated with human immunodeficiency virus infection * New background PAH therapy within 12 weeks * Significant dose change in background PAH therapy within 12 weeks. * Untreated severe obstructive sleep apnea diagnosed by polysomnography * Evidence of left-sided valvular disease or systolic dysfunction on echocardiogram (≥ moderate mitral or aortic disease or LV ejection fraction ≤ 50%) * Glomerular filtration rate \<40 mls/min/1.73m2 * Child-Pugh Class C cirrhosis * Untreated hypo- or hyper-thyroidism * Pregnant or breastfeeding * Active or planned use of hormone supplements, oral contraceptive pills, hormonal therapies * History of breast, ovarian, uterine, testicular or prostate cancer * Current use of another investigational PAH therapy * Contraindication to MRI (e.g., metal device or fragment) * History of significant non-adherence or circumstance which would threaten ability to comply with cross-over design and study visit schedule