This is a prospective longitudinal cohort study to determine the value of HRV obtained using noninvasive actigraphy to quantify the response to pulmonary vasodilator therapy in newly diagnosed PAH patients

This single center prospective longitudinal cohort study will take place at the University of Cincinnati (UC). We will screen adult patients newly diagnosed with PAH and placed on targeted pulmonary vasodilator therapy by their treating physician for enrollment.

We will enroll 35 eligible participants over a two-year period. HRV will be measured using the Polar™ H10 wearable chest actigraphy device in conjunction with analytic software to capture HRV data.

After enrollment and completion of the baseline visit, study participants will receive chest actigraphy device to measure their heart rate for a two hour period twice a week during study participation. Follow up research visits will be conducted at one-month, 3-months, and 6-months to sync the actigraphy device and assess any AE's.

In-between these visits, study staff will communicate with participants at two weeks, two months, 4 months, and 5 months, to identify and address any issues with study actigraphic device, assess any adverse events and maintain regular contact with study participants.

Throughout study participation, subjects will continue routine clinical care at the direction of their treating physician as needed.

Inclusion Criteria:

• All adult patients (ages 18-70) of any functional class with a new diagnosis of PAH (World health Organization Group 1) placed on targeted therapy
• Eligible PAH etiologies include idiopathic PAH, associated with connective tissue disease, human immunodeficiency virus, hereditary, or portopulmonary hypertension
• Right heart catheterization (RHC) hemodynamics with a mean pulmonary arterial pressure >=20 millimetres of mercury at rest, a pulmonary capillary wedge pressure <= 15 millimetres of mercury, and a pulmonary vascular resistance >= 3 woods units

Exclusion Criteria:

• Inability to undergo (non-contrast) Magnetic Resonance Imaging (MRI) testing
• On chronotropic agents (Beta-Blockers, anti-arrhythmic medications, etc.) that could affect the calculation and interpretation of HRV measures
• Conditions that could affect the accuracy of MRI imaging, including a history previously repaired or unrepaired congenital heart defects, ventricular or atrial septal defects, or other anatomic cardiac abnormalities)
• Inability to complete a six-minute walk test
• Currently being on targeted PAH therapy at the time of consent and enrollment
• Thyroid disease, known arrhythmias in the past six months, uncontrolled anemia with a hemoglobin less than 7 grams per deciliter, untreated coronary artery disease or a diagnosis of myocardial infarction in the past 6 months, the presence of a cardiac pacemaker
• Clinically significant lung disease (including pulmonary function testing forced vital capacity < 60%), a positive ventilation/perfusion scan, uncontrolled sleep apnea not adherent with noninvasive positive pressure ventilation
• Unable to consent, pregnant women, and prisoners.

Patients seen at the University of Cincinnati PAH Clinic in Cincinnati, Ohio