Non-alcoholic fatty liver disease and cardiovascular disease: epidemiological, clinical and pathophysiological evidences

Non-alcoholic fatty liver disease is recognized as the most common and emerging chronic liver disease in western countries. The disease has been traditionally interpreted as a possibly progressing condition to liver fibrosis and cirrhosis. However, recently, a large number of publications have demonstrated that people with non-alcoholic fatty liver have an increased chance of developing cardiovascular diseases, which represent the major causes of death in this setting. This association is mainly explained by the atherogenic profile of the metabolic syndrome a condition frequently associated with fatty liver, which may represent its hepatic component. Some studies have also shown an association independent of traditional risk factors or of the clinical features of the metabolic syndrome. In this setting, cardiovascular disease seems to be the consequence of low-grade chronic inflammation and increased oxidative stress. Most studies did not differentiate cardiovascular risk between simple steatosis and non-alcoholic steatohepatitis, although the latter seems to be at higher cardiovascular risk. Few studies have investigated the direct correlation between hepatic inflammation and atherosclerosis. Genetic studies will probably improve the interpretation of the increased cardiovascular risk in patients with fatty liver and no metabolic syndrome.