Fibrosis-4 index reflects right-sided filling pressure in patients with heart failure

The fibrosis-4 index (FIB-4 index) is a marker of liver fibrosis. It has been reported that the FIB-4 index in compensated phase is associated with estimated right-sided filling pressure and poor prognosis in patients with heart failure. However, the relationship with invasively obtained right-sided cardiac pressures has been unclear. Hemodynamic status was evaluated by right heart catheterization in 189 heart failure patients who were in a clinically compensated phase between January 2015 and September 2017. Patients were assigned to two groups based on a median FIB-4 index of 2.15, then hemodynamic parameters and event rates were compared. Endpoint was defined as a composite of all-cause death, readmission for heart failure, or left ventricular-assist device implantation. Then, we also investigated correlations between the FIB-4 index and clinical factors, including hemodynamic parameters. Patients with a high FIB-4 index were significantly older (76 [IQR, 63-80] vs. 65 [IQR, 56-74] years, P < 0.001) and had higher right atrial pressure (RAP; 7 [IQR, 5-11] vs. 4 [IQR, 1-6] mmHg, P < 0.001) and pulmonary capillary wedge pressure (16 [IQR, 12-22] vs. 12 [IQR, 8-19] mmHg, P = 0.011) than those with a low FIB-4 index. The FIB-4 index correlated more strongly with parameters of right-sided than left-sided HF (RAP, R = 0.41, P < 0.001; inferior vena cava diameter, R = 0.44, P < 0.001; pulmonary capillary wedge pressure, R = 0.15, P = 0.038; brain natriuretic peptide, R = 0.14, P = 0.29). Multiple regression analysis showed that the FIB-4 index independently correlated with RAP. In conclusion, the FIB-4 index can non-invasively reflect right-sided filling pressure, which might explain why it is associated with a poor prognosis, among patients with heart failure.