The investigators will evaluate ventricular reversed remodelling after double lung transplantation (LTX) in patients with pulmonary arterial hypertension (PAH), measured with cardiac magnetic resonance imaging (MRI). Reversed remodelling will be compared with control patients without PAH (e.g. Cystic Fibrosis) who will also undergo LTX.

In this study, pre-LTX and six-months post-LTX measurements will be compared with each other and between the primary and control group.

Pre- and post-LTX measurements include:

Past medical history: Including basic diagnosis; interventions, surgery and transplant related complications (re-operations, hospitalizations, infections) and medication history; These data will be collected by studying the medical files including surgical reports.

Present medical history: Including NYHA class.

Physical examination: Including length and weight.

Cardiac Magnetic Resonance Imaging:

• Ventricular volume, function and mass measurements
• Flow measurements of the pulmonary artery and aorta
• Disease specific measurements (e.g. septal bowing, RV trabecularisation, etc.)
• T1-mapping

Transthoracic Echocardiography

Resting ECG: Disease specific electrophysiological findings (e.g. QRS-duration, right bundle branch block).

Laboratory evaluation:

• NT-pro-BNP
• eGFR
• Remaining serum will be stored.

Inclusion criteria:

• Patients who are on the waiting list for double-LTX, in our institution, for pulmonary arterial hypertension.
• Eligible for CMR imaging
• No claustrophobia
• No pacemaker, ICD, etc.
• Informed consent

Exclusion criteria:

• Inability to comply with primary endpoint measures.
• Body mass index ≥40 kg/m2.
• Pregnant patients will not be included, they may be included >3 months after pregnancy.
• Patients with age <18 years.

Patients with pulmonary arterial hypertension and control patients without increased pulmonary artery pressure who are on the waiting list for double-LTX