Purpose: This study aimed to examine the changes in brain diffusion in patients with heart failure (HF) by measuring the apparent diffusion coefficient (ADC) and to investigate the relationship between these changes and cardiac injury features. Methods: The study included 49 patients with HF and 39 healthy controls. Cognitive performance was assessed using the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA). All participants underwent a brain DWI scan, followed by cardiac MR in patients with HF. The ADC values in different regions of the brain were estimated using region-of-interest analysis. Cardiac MR was used to evaluate left ventricular function and the volume of late gadolinium enhancement (LGE). Group differences in ADC values were analysed using generalised linear mixed modelling. Correlation analysis was used to explore the associations between brain diffusion alterations, cognitive performance, and cardiac injury features. Results: Patients with HF showed significantly increased ADC values in several brain regions, including the frontal, parietal, temporal, occipital lobes, cingulate cortex, hippocampus, cerebellum, and deep nuclei. ADC values in the right hippocampus, right amygdala, and bilateral insula were negatively correlated with MoCA scores. ADC values in the left inferior occipital gyrus (r = 0.570, P<0.001) and lobule VI of the cerebellar hemisphere (r = 0.560, P = 0.001) were correlated with LGE volume. Conclusion: These findings suggest that specific brain regions in patients with HF experience microstructural changes associated with cognitive impairment. Moreover, chronic brain microstructural alterations may be related to myocardial fibrosis in patients with HF.