London | Nonalcoholic fatty liver disease (NAFLD) is an independent risk factor for atherosclerosis and therefore cardiovascular disease (CVD), a new study suggests. CVD is primarily the cause of death of patients with NAFLD.
The extent to which NAFLD itself, rather than associated conditions such as diabetes, obesity, or atherogenic dyslipidemia, is responsible for increased cardiovascular death has been a matter of debate. Now, researchers from Pitie-Salpetriere Hospital and Pierre and Marie Curie University in France have found that NAFLD is an independent risk factor for atherosclerosis and therefore CVD.
NAFLD is an increasingly common condition in patients with obesity, type 2 diabetes, atherogenic dyslipidemia and arterial hypertension, researchers said. Evidence indicates that the fatty and inflamed liver expresses several pro-inflammatory and procoagulant factors, as well as genes involved in accelerated atherogenesis, said Raluca Pais from Pierre and Marie Curie University.
This raises the possibility that the link between NAFLD and cardiovascular mortality might not simply be mediated by shared, underlying, common risk factors, but rather that NAFLD independently contributes to increasing this risk, said Vlad Ratziu from Pierre and Marie Curie University.
Researchers studied almost 6,000 patients between 1995 and 2012 to assess whether NAFLD is incidental to or is the cause of atherosclerosis of the carotid arteries, the major blood vessels in the neck that supply blood to the brain, neck, and face. All patients were examined using carotid ultrasound with measurement of carotid intima-media thickness and carotid plaques, researchers said.
Using the Fatty Liver Index (FLI), a well-validated biomarker panel, researchers observed that steatosis (fatty liver) is associated with carotid intima-media thickness (C-IMT), a pre-atherosclerotic lesion that predicts cardiovascular events. C-IMT increased proportionally with FLI, and this association was independent of traditional cardiometabolic risk factors, researchers said.
Steatosis predicted C-IMT better than diabetes or dyslipidemia, after adjustment for metabolic syndrome and cardiovascular risk factors, in 5,671 patients, they said. Long-term follow-up in 1,872 patients after eight years added a further critical piece of information by confirming that patients with fatty liver were more likely to develop carotid plaque over time, researchers said.
Steatosis occurred in 12 per cent and carotid plaques in 23 per cent of these patients. C-IMT increased in patients with steatosis, but did not change in those who stayed free of steatosis, they said. In patients with metabolic syndrome at risk for cardiovascular events, NAFLD contributes to early atherosclerosis and its progression, independent of traditional cardiovascular risk factors, researchers said. The findings were published in the Journal of Hepatology.