Non-alcoholic fatty liver disease (NAFLD): a novel cardiovascular risk factor

Nonalcoholic fatty liver disease (NAFLD) is a common form of primary fatty liver almost universally asso- ciated with metabolic risk factors. Histologically, NAFLD is categorized as simple steatosis, which follows a benign course, and its potentially progressive counterpart, nonalco- holic steatohepatitis (NASH). Practicing physicians, while relatively aware of liver-related morbidity and mortality of NAFLD, appear to be more reluctant to engage their NAFLD patients in a protocol of screening and surveillance for car- diovascular disease. This occurs contrary to the alert made by scientific societies about the importance of focusing on vas- cular complications in addition to liver-related complications. Aiming to get further insight into such a controversial issue, we critically reviewed all the available literature on this hot topic. Clinical studies have been discussed first; next the pu- tative biological mechanisms involved in the NAFLD-athero- sclerosis association have been reviewed. Finally, recommen- dations issued by hepatological scientific societies have been compared. Data strongly support the association of NAFLD with en- dothelial dysfunction, carotid and coronary atherosclerosis. However, whether it is simple steatosis or NASH or both re- mains to be ascertained by large prospective studies recruiting subjects with biopsy-proven NAFLD and definite cardiovas- cular outcomes. Mechanisms linking NAFLD and early atherosclerosis in- clude subclinical inflammation, insulin resistance/diabetes, dyslipidemia, prothrombotic changes, hyperuricemia and probably chronic kidney disease, all of which appear to be af- fected to a large extent by hepatic histological changes seen in NAFLD, and particularly in NASH. In conclusion, our study confirms that NAFLD patients should be screened and monitored with reference to their car- diovascular risk.