FAPi-PET/CT as surrogate marker for subclinical myocardial fibrosis is a prognostic tool for patients undergoing left-sided heart valve surgery.

BACKGROUND

The aim of this study was to evaluate fibroblast activation protein (FAP)-targeted positron emission tomography and computed tomography (PET/CT) imaging as surrogate marker for cardiac fibrosis and therefore as prognostic tool for patients with left-sided valvular heart disease undergoing open-heart surgery.

RESULTS

In 13 patients (6 men, 7 women; mean age ± SD, 62 ± 13 years) scheduled for aortic and/or mitral valve surgery (aortic, n = 3; mitral, n = 9; both, n = 1) preoperative FAPi-PET/CT ([68Ga]Ga-RTX1363S) was perfomred. FAP-positive volume and FAP uptake was quantified by different methods (isocontour with fixed and variable threshold) and correlated to preoperative clinical parameters, including (left ventricular ejection fraction (LVEF) and serum N-terminal prohormone of brain natriuretic peptide (NT-proBNP), as well as to changes in LVEF from preoperatively to 3–6 months follow-up (available for n = 11 patients). FAP-uptake in the left ventricular (LV) myocardium was highly variable in the study cohort. Isocontour-55%-based FAP-positive volume was found to correlate statistically significantly with preoperative LVEF (p = 0.03) and preoperative NT-proBNP (p = 0.02). In addition, we found a significant correlation with the change in LVEF from preoperatively to 3–6 months follow-up examination (p = 0.04).

CONCLUSIONS

Preoperative FAPi PET/CT seems to have potential to predict LVEF changes after valvular heart surgery and may therefore be an important tool for risk stratification of asymptomatic patients with left-sided valvular heart disease to support the appropriate timing of valvular surgery.