Obese individuals with nonalcoholic fatty liver disease (NAFLD) have higher instances of cardiovascular disease and heart failure, according to results of a study published online Jan. 26 in the journal Radiology.

The most common liver disease among the general population, NAFLD affects up to 30 percent of all people and is prevalent in 70 to 90 percent of obese individuals and those with type 2 diabetes. The disease is considered to be the manifestation of the metabolic syndrome—a group of risk factors including high blood pressure and excessive abdominal fat that raise the risk of heart attacks, stroke and other health problems.

But despite similar risk factors, determining exactly how NAFLD and heart failure are connected can be tricky, says lead author Ralph Widya, MD, and his colleagues at the Leiden University Medical Center in the Netherlands.

“The individual components that define the metabolic syndrome are also considered risk factors of both NAFLD and cardiovascular disease,” the researchers wrote. “It is yet unclear whether the association between NAFLD and cardiovascular disease is a consequence of shared risk factors within the metabolic syndrome or exists independently of these risk factors.”

To solve this puzzle, Widya and his team performed MR spectroscopy and MRI scans to assess hepatic triglyceride content and left ventricle diastolic heart function in 714 men and women aged 45 to 65 years. Forty-seven percent of the subjects were categorized as overweight, while 13 percent were categorized as obese.

Their results showed that only patients in the obese subgroup had a statistically significant correlation between increased liver fat and reduced heart function.

“Hepatic triglyceride content was significantly associated with diastolic function independent of confounding factors including the metabolic syndrome, VAT, and total body fat in obese adults aged 45–65 years,” Widya and his colleagues wrote. “This association was not statistically significant in normal-weight and overweight subgroups.”

Despite the success of the study in linking NAFLD to heart failure in obese subjects, the researchers cautioned that more studies are needed to better understand the association and to determine how best to use the results for improving patient care and outcomes.

“Fatty liver itself could, at least in obesity, pose a risk of myocardial dysfunction above and beyond known cardiovascular risk factors that are clustered within the metabolic syndrome,” the authors concluded. “Future studies with larger samples sizes are required to investigate to what extent the association exists and differs in normal-weight, overweight, and obese persons to unravel its clinical relevance.”