FABP3, a fatty acid-binding protein, is involved in intracellular fatty acid transport, predominantly expressed in cardiac cells. Its serum levels increase during myocardial infarction (MI) but its kinetics at the acute phase of MI is not known.

We explored whether the plasma level kinetics of FABP3 could predict the severity of MI.

We prospectively enrolled 412 consecutive ST-elevation myocardial infarction (STEMI) patients undergoing percutaneous coronary intervention (PCI) in a prospective cohort. Blood samples were collected at 5 time points: admission, 4, 24, 48hours, and 1-month post-admission. FABP3 plasma levels were assessed using ELISA. Patients underwent cardiac magnetic resonance imaging (MRI) after one month. Clinical outcomes were prospectively recorded over 12months.

The mean age of the studied population was 59±12years, with 55.6% having anterior MI. Median LVEF was 51% IQR [45–58]. FABP3 plasma levels reached a peak as early as admission and decreased from 18.5 [6.8–66.4] ng/mL at admission to 16.9 [7.7–37.8] ng/mL at 4h and gradually decreased to 4.3ng/mL [3.9–5.1] at 24h, 4.0ng/mL [3.7–4.4] at 48h and 3.8ng/mL [3.6–4.1] at 1 month (Fig. 1A). The FABP3 plasma level as early as admission and 4h was significantly correlated with infarct size (IS) (r=0.37, P<0.0001 and r=0.66, P<0.0001 respectively) and left ventricular ejection fraction (LVEF) assessed by MRI at 1-month (r=−0.33, P<0.0001 and r=−0.58, P<0.0001, respectively). Furthermore, patients with admission FABP3 plasma levels above the population median (18.5ng/L) were more likely to experience major adverse cardiovascular events (MACE) during the first 12months after STEMI [adjusted hazard ratio of 3.2 (1.72–6.26), P=0.01] (Fig. 1B). In a multivariable Cox regression analysis including age, gender, troponin peak, and TIMI flow grade post-PCI, admission serum FABP3 level remained associated with an increased risk of MACE over the 12-month follow-up (adjusted HR=2.3 (1.1–5.2), P=0.03).

Elevated circulating FABP3 levels upon admission for coronary angiography were independently associated with an increased risk of MACE in our population. The early measurement of FABP3 could be a valuable prognostic marker in STEMI patients, potentially guiding personalized therapeutic strategies in the future.