Tissue-level evidence of fibroblast activation protein inhibitor imaging in hypertrophic obstructive cardiomyopathy: a case series.

Background:Myocardial fibrosis is a key pathological factor for the occurrence of ventricular arrhythmias in hypertrophic obstructive cardiomyopathy (HOCM). Case summary:This case series reports on two patients diagnosed with HOCM who underwent 18F-fibroblast activation protein inhibitor (FAPI) positron-emission tomography/computed tomography imaging and Morrow myotomy procedure. The collected myocardial tissue was examined histopathologically. Both patients exhibited intense and heterogeneous 18F-FAPI uptake in the septum, with significant number of activated fibroblasts. Discussion:Enhanced 18F-FAPI uptake was observed before irreversible fibrosis, and the degree of 18F-FAPI uptake was higher in tissue with greater fibrosis. 18F-FAPI imaging may provide a promising tool for guiding surgical strategy in HOCM, and further research is needed to fully explore its potential in clinical practice.