The Area of Fibroblast Activation Exceeds the Hypoperfused Infarct Region in Patients with Acute Myocardial Infarction

135 Introduction: Radiolabelled inhibitors of fibroblast activation protein (FAPI) have been introduced for PET imaging and may identify an early pathway leading to cardiac fibrosis. We describe molecular imaging patterns in patients early after acute myocardial infarction (AMI). Methods: Cardiac magnetic resonance imaging (CMR), perfusion SPECT, and PET/CT with 68Ga-FAPI-46 (kindly provided by University of Heidelberg) were performed in 12 patients at 6-11 days after reperfused AMI. MRI defined cardiac function and extent of late gadolinium enhancement (LGE). SPECT polar maps were generated and compared to normal database for calculation of perfusion defect size. Regional standardized uptake values (SUV) were determined for FAPI, and quantitative polar maps defined the area of FAPI upregulation significantly elevated above blood pool (+ 2 standard deviations). Segmental analysis of FAPI-signal and LGE transmurality was performed using AHA 17-segment model. Results: All patients exhibited regional FAP signal enrichment at the site of the infarct relative to blood pool (SUVpeak 5.8±1.6 vs. 2.1±0.5; p