Simultaneous F-labeled AlF-FAPI PET/MR images targeting the myocardial fibrosis in coronary artery disease and degenerative mitral valve regurgitant participants with left ventricular mechanical dyssynchrony.

Background: Myocardial fibrosis contributes to LV mechanical dyssynchrony and fibroblast activation protein is considered as a specific biomarker related to tissue remodeling. The authors aimed to explore the relationship between LVMD and myocardial fibrosis, and patterns of LV fibrosis distribution in CAD and Degenerative Mitral Valve Regurgitant (DMVR) participants by the technique of F-AlF-FAPI PET/MR.

Methods: 37 CAD and DMVR participants with LVMD and normal ones underwent cardiac PET/MR imaging, the correlations between SUV of FAPI-uptakes and score/percentage of LV wall thickening, peak myocardial strains, and displacements were analyzed in PET/MR images, and ejection fractions and function parameters of mitral valve were compared.

Results: There was inverse correlation between SUV and score/percentage of LV wall thickening, peak circumferential and short-axial radial myocardial strains, and global peak myocardial strains and ejection fractions showed a decrease significantly in participants with heart diseases. In CAD participants, FAPI was distributed in the ischemic coronary arteries regions. Functions of myocardium in LAD and RCA regions were sensitive to fibrosis, however, those in LCX regions were resistant to fibrosis. In DMVR participants, high uptakes of FAPI were the locations of the valve annulus and papillary muscles, and SUV in the basal inferospetal/basal inferior segments were a positive correlation with function parameters of the mitral valve.

Conclusion: Uptake of F-AlF-FAPI in the myocardium could detect fibrosis and predict LVMD in CAD and DMVR participants. Moreover, there were different distributions of FAPI-uptake in those participants. In DMVR participants, SUV in the basal inferospetal/basal inferior segments could assess dysfunction of the mitral valve.