Predicting reverse remodeling following valve replacement in patients with valvular heart disease: a longitudinal ^99mTc-FAPI SPECT/CT imaging study.

Abstract

In patients with valvular heart disease (VHD), fibroblast activation induced by pressure or volume overload can be identified by molecular imaging with fibroblast activation protein inhibitor (FAPI). The study sought to explore the potential of serial FAPI imaging for monitoring the reverse myocardial remodeling triggered by valve replacement. A cohort of 31 VHD patients scheduled for transcatheter or surgical valve replacement underwent ^99mTc-FAPI SPECT/CT imaging and echocardiography. All patients repeated echocardiography and 22 of them completed repeat FAPI scans at 3-month follow-up. Cardiac FAPI uptake was quantified as maximum standardized uptake value (SUV_max), maximum of myocardial-to-blood ratio (TBR_max), and fibroblast activation volume (FAV). Myocardial remodeling patterns were evaluated through a comprehensive analysis of left ventricular geometric parameters derived from echocardiography. Myocardial FAPI uptake showed heterogeneous among VHD patients (range: SUV_max 0.67-8.33; TBR_max 1.13-7.50; FAV 0-597 mL). FAPI uptake significantly correlated with levels of circulating N-terminal prohormone of brain natriuretic peptide and left ventricle mass index before valve replacement. Following relief of overload, 22 patients who underwent repeat FAPI imaging demonstrated significant reductions in TBR_max (3.31 [1.73-4.87] vs. 2.43 [1.63-4.23], p = 0.029) and FAV (31.5 [0-227] vs. 12.0 [0-144] mL, p = 0.004). Follow-up echocardiography revealed that 9 out of 31 patients transitioned to normal geometry from concentric or eccentric hypertrophy, achieving complete reverse remodeling. Multivariable regression suggested baseline FAPI uptake intensity TBR_max significantly associated with complete reverse remodeling post-intervention after adjustment (OR: 0.288 [0.097-0.852], p = 0.024). ^99mTc-FAPI SPECT/CT imaging is feasible to quantitatively track dynamics of fibroblast activation following valve replacement. Patients with lower preprocedural fibrotic activity identified by FAPI imaging may have greater potential for complete reverse remodeling.