Comparison of cardiac activated fibroblast imaging and magnetic resonance imaging in patients with COVID-19–related myocarditis

Abstract

Abstract Background This study aimed to explore the association of cardiac fibroblast activation and cardiac magnetic resonance (CMR) imaging parameters in patients with myocarditis following coronavirus disease 2019 (COVID-19) infection. Methods In this prospective study, four patients with COVID-19–related myocarditis underwent 99mTc-labeled–hydrazinonicotinamide-fibroblast activation protein inhibitor-04 (99mTc-HFAPi) single photon emission computed tomography/computed tomography (SPECT/CT) and CMR imaging. Segmental 99mTc-HFAPi activity was quantified as the percentage of average segmental myocardial count × global left ventricular target-to-background ratio. T1/T2 values, extracellular volume (ECV), and late gadolinium enhancement (LGE) were analyzed at CMR. The consistency between myocardial 99mTc-HFAPi activity and CMR parameters was explored. Results In patients with myocarditis, the proportion of segments with abnormal 99mTc-HFAPi activity was significantly higher than those with abnormal LGE (81.3% vs. 60.9%, p = 0.011), abnormal T2 (81.3% vs. 50.0%, p < 0.001), and abnormal ECV (81.3% vs. 59.4%, p = 0.007) but was similar in those with abnormal native T1 (81.3% vs. 73.4%, p = 0.291). Meanwhile, 99mTc-HFAPi imaging had good consistency with native T1 (kappa = 0.69). Conclusion Increased cardiac 99mTc-HFAPi activity is present in COVID-19–related myocarditis, which is correlated with the native T1 values in CMR.