Increased abdominal fat may boost cardiovascular disease risk factors

An increase in the change in abdominal subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) volume was associated with an increased incidence of cardiovascular disease risk factors, according to an analysis of a long-term prospective study.

Meanwhile, a decrease in the change in SAT and VAT attenuation was associated with an increased incidence of cardiovascular disease risk factors. The researchers found that most of the associations remained significant after accounting for body mass index or waist circumference changes or respective abdominal adipose tissue volumes.

Lead researcher Jane J. Lee, PhD, of the National Heart, Lung and Blood Institute, and colleagues published their results online Sept. 26 in the Journal of the American College of Cardiology.

“These findings suggest that adverse changes in fat quantity and attenuation are associated with changes in [cardiovascular disease] risk factors above and beyond the contribution of generalized adiposity, central adiposity or absolute levels of respective fat volume,” the researchers wrote.

Previous studies found that greater accumulation of abdominal SAT and VAT was associated with a higher prevalence of diabetes, hypertension and hypertriglyceridemia, according to the researchers.

For this study, they evaluated 1,106 participants who were part of the Framingham Heart Study’s multidetector CT substudy from 2002 to 2005 and 2008 to 2011. They noted that participants underwent abdominal scans via an eight-slice multidetector CT while lying in the supine position.

At baseline, the mean age of participants was 45.1 years old, and 44.1 percent were women.

During a mean of 6.1 years of follow-up, the participants weight increased by 2.4 kg, their body mass index increased by 1.1 kg/m2 and their waist circumference increased by 3.7 cm. They also gained an average of 602 cm3 of SAT volume and 703 cm3 of VAT volume, while the average fat attenuation decreased by 5.5 Hounsfield units (HU) for SAT and increased by 0.07 HU for VAT attenuation.

The researchers found that an additional 500 cm3 increase in fat volume was associated with incident hypertension, hypertriglyceridemia and metabolic syndrome. They added that similar trends were found for each additional 5 HU decrease in abdominal adipose tissue attenuation.

They noted that the study had a few limitations, including its observational design, which limited causal inferences. The trial also mostly included white participants, which could have limited the generalizability of the findings to other racial or ethnic backgrounds. In addition, they did not perform interscan reproducibility.

“Increasing abdominal fat volume and decreasing fat attenuation (a measure of fat quality), as determined by [multidetector CT] scans, are associated with worsening CVD risk factors beyond associations with generalized or central adiposity,” the researchers wrote. “Further studies are warranted to clarify the mechanisms that underlie these associations.”