129 Xenon MRI as a Biomarker for Diagnosis and Response to Therapy in Pulmonary Arterial Hypertension (PAH)

Subject Enrollment This study will consent and enroll 20 subjects total.

• For Arm 1, 10 subjects with Idiopathic Pulmonary Arterial Hypertension (IPAH) will be consented and enrolled. For Arm 2, 10 subjects with Connective Tissue Disease Associated Pulmonary Arterial Hypertension (PAH-CTD) will be consented and enrolled.

Study Design This study will be observational. Subjects in both arms of the trial will undergo a 129Xe MRI/MRS at timepoints of baseline, 3 months, 6 months, and 12 months. In addition to the this, data from standard of care assessments, such as labs, echocardiography, and six-minute walk distance (6MWD), will also collected at these timepoints.

Primary Study Endpoints The primary endpoint for this trial will be the change in defect + low percentage of RBC signal on hyperpolarized 129Xe MRI from baseline to 12 months

Secondary Study Endpoints

There will be several secondary endpoints for this trial:

• Change in regional and global RBC Oscillation Amplitudes on hyperpolarized 129Xe MR spectroscopy from baseline to 12 months
• Change in 6MWD from baseline to 12 months
• Change in NTproBNP from baseline to 12 months
• Change in WHO FC from baseline to 12 months

Primary Safety Endpoints

There will be several primary safety endpoints for this trial:

• Frequency of Adverse Events (AE) and/or Serious Adverse Events (SAE)
• Withdrawals due to adverse event or death
• Incidence of Adverse Events of Significant Interest (AESI):
• Electrocardiogram and any findings
• Physical examination and vital signs

Inclusion criteria

Arm 1 -IPAH

• Age: 18-75 years
• WHO functional class 2 or 3
• Mean pulmonary artery pressures > 20 mmHg
• Pulmonary capillary wedge pressure ≤15 mmHg
• Pulmonary vascular resistance > 2 Wood Units (WU)
• No other cause identified for PAH

Arm 2 -PAH-CTD

• Age: 18-75 years
• WHO functional class (FC) 2 or 3
• Mean pulmonary artery pressures > 20 mmHg
• Pulmonary capillary wedge pressure ≤15 mmHg
• Pulmonary vascular resistance > 2 WU
• Diagnosis of connective tissue disease

Exclusion criteria

• PH other than Idiopathic PAH or PAH associated with CTD; any conditions that prevent the performance of 129Xe MRI scans will be excluded from the study.