Introduction: Pulmonary arterial hypertension (PAH) is a progressive disease of the pulmonary vasculature leading to right ventricular (RV) failure. PAH patients carrying an associated pathogenic gene mutation have a more impaired RV function compared to non-carriers despite similar afterload. The presence of a pathogenic gene mutation could lead to RV impairment even in the absence of disease. Cardiac magnetic resonance imaging (CMRi) may provide insight to early changes in right ventricular structure and function.

Aim: Detection of early changes in RV morphology and function using CMRi in UMCs at risk for PAH.

Methods: 35 UMCs (31 BMPR2, 3 TBX4, 1 GDF2) (mean age 43.76 ± 15.95 yrs , 54.1% female) and 20 healthy controls (mean age 43.1 ±17.65 yrs, 45% female) underwent CMRi as part of an annual screening program. Images were quantitatively analyzed to assess cardiac features and compared with healthy controls.

Results: No differences in right ventricular volumetrics were seen between healthy controls and UMCs. However, myocardial strain analysis at baseline demonstrated an increased global right ventricular circumferential strain (-15.54± 3.31 vs. -13.21 ± 2.57;p= 0.013) in UMCs, in particular at the sub-tricuspid region (-16.26 ± 4.10 vs -12.95± 2.93; p=0.004) and the basal region (-12.73±3.31 vs. =10.47 ±3.77; p= 0.048) of the right ventricle

Conclusion: Unaffected mutation carriers do not exhibit impaired RV function. On the contrary, they exhibit increased RV circumferential strain. This is possible evidence of early cardiac adaptation as a response to changes in the pulmonary vasculature, which has yet to be confirmed.