Cardiovascular disease in patients with non-alcoholic fatty liver disease

As it affects almost every third individual in the general population in the Western world, non-alcoholic fatty liver disease (NAFLD) represents the most common cause of chronic liver disease and the most common cause of liver transplantation. Recently, NAFLD has gained much attention in the metabolic field. A continuously increasing amount of evidence suggests that NAFLD is strongly associated with the obesity epidemic and its complications (e.g. insulin resistance, hypertension and dyslipidemia) and precedes the manifestation of type 2 diabetes and cardiovascular disease. However, it remains a matter of debate whether the close relationship to cardiovascular disease is explained because NAFLD simply represents a manifestation of the obesity-related metabolic disorders (collectively called the metabolic syndrome) or whether NAFLD is an independent determinant of metabolic dysfunction leading to cardiovascular disease. Another intriguing issue is the fact that, while the association between NAFLD and cardiovascular disease (CVD) is undisputed, some studies fail to show a similar relationship of NAFLD to incident cardiovascular events. A study by Wong et al [1] addressed these 2 issues by prospectively following 612 consecutive patients who were first screened for fatty liver by ultrasonography and then underwent a coronary angiogram. Significant (defined as >= 50% stenosis in at least one coronary artery) coronary artery disease was present in 84.6% of those with fatty liver and 64.1% of those without, which confirmed a strong association between fatty liver and coronary artery disease. After adjustment for many demographic and metabolic factors in a multiple regression analysis, fatty liver and serum alanine aminotranferase levels remained independently associated with coronary artery disease. The patients with coronary artery disease were then followed for the occurrence of a cardiovascular event, defined as cardiovascular death, non-fatal myocardial infarction and the need for further coronary intervention. After a mean follow-up of about 22 months, there was no difference in the rate of events between patients with and without fatty liver. The authors concluded that fatty liver is an independent determinant of coronary artery disease; however, it cannot be used as a marker to predict clinical events in patients with established coronary artery disease.