Changes in concentrations of circulating fibroblast activation protein alpha are associated with myocardial damage in patients with acute ST-elevation MI.

ABSTRACT

BACKGROUND: Fibroblast activation protein alpha (FAP) is a membrane-bound serine protease expressed by activated fibroblasts after myocardial infarction (MI). Reduced circulating FAP levels were associated with increased mortality in patients with acute coronary syndrome. We hypothesized that FAP concentrations are altered after acute ST-elevation MI (STEMI), and related to myocardial damage. METHODS: We measured circulating FAP concentrations in blood plasma of 60 patients on admission, day 1, day 3 and day 5 after STEMI, and in 25 apparently healthy blood donors as controls. RESULTS: Plasma FAP concentrations were lower in STEMI patients on admission (71ng/mL) than in blood donors (101ng/mL, P<0.0001). FAP concentrations declined in STEMI patients from admission to day 3 (66ng/mL, P<0.05) and day 5 (57ng/mL, P<0.05). FAP concentrations on day 5 were inversely correlated with maximum CK and maximum CRP levels. In a multiple linear regression analysis, maximum CRP was independently associated with low FAP concentrations on day 5 after STEMI. When stratified according to the absolute amount of FAP change from admission to day 5 (ΔFAP), patients with high ΔFAP (-22ng/mL) had worse left ventricular function, higher levels of hs-cTnT, CK on admission, maximum CK and CRP than patients with low ΔFAP (-3ng/mL). CONCLUSIONS: Our study first demonstrates alterations of circulating FAP concentrations acutely after STEMI. A greater decline of circulating FAP concentrations in the first 5days after STEMI is associated with increased myocardial damage and inflammation. Measurement of circulating FAP might help to better understand the relation of myocardial injury and inflammatory response in the individual patient.