Liver fibrosis and outcomes of atrial fibrillation: the FIB-4 index

Background and aims Liver diseases play an important role in the development and progression of atrial fibrillation (AF). The Fibrosis-4 (FIB-4) index is a non-invasive score recommended for detecting liver fibrosis. Since the association between liver fibrosis and outcomes of AF patients is still not well defined, we aim to analyze prognosis impact of FIB-4 index in those patients. Methods A retrospective population-based cohort study was performed with 12,870 unselected patients from a single health area in Spain with AF from 2014 to 2019. Cox regression models were used to estimate the association of FIB-4 index with mortality. The association with ischemic stroke (IS), major bleeding (MB), acute myocardial infarction (AMI), and heart failure (HF) was assessed by competing risk analysis. Results A total of 61.1%, 22.0%, and 16.9% were classified as low, moderate and high risk of liver fibrosis according to FIB-4 index, respectively. During a mean follow-up of 4.5 ± 1.7 years, FIB-4 index was associated with mortality (adjusted HR 1.04; 95% CI 1.01–1.06; p = 0.002), MB and HF (adjusted sHR 1.03, 95% CI 1.01–1.04; p = 0.004), but not with IS or with AMI. The association between FIB-4 and MB was only found in patients treated with vitamin K antagonists, not in patients on direct oral anticoagulants. Conclusions The FIB-4 index, a non-invasive scoring method for evaluating liver fibrosis, is independently associated with all-cause mortality, MB and HF in patients with AF, suggesting that it may be useful as a risk assessment tool to identify adverse outcomes in patients with AF. Graphical abstract