Obesity: Fat around the heart may increase heart attack risk

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In terms of heart attack risk, having excess fat around the heart may be worse than having a high body mass index or a thick waist, according to research published in the August issue of Obesity.

According to the researchers from Wake Forest University Baptist Medical Center in Winston-Salem, N.C., and colleagues, the study was among the first to explore whether there is a link between fat deposits around the heart, or pericardial fat, and the development of hard, calcified plaque in the arteries.

"The distribution of body fat may be as important as the amount of body fat in determining risk of heart attacks," said lead author Jingzhong Ding, MD, an assistant professor of gerontology. “Even a thin person can have fat around the heart.”

The investigators examined data from the Multi-ethnic Study of Atherosclerosis (MESA), a $68 million study, involving 6,800 participants nationwide, to explore their hypothesis that fat around the arteries in the heart contributes to inflammation and to increased risk of fatty deposits in the vessels.

Ding said the study is based on a new idea in medicine – that excess fat around the heart and other organs may impair their function. Pericardial fat is known to have a higher secretion of inflammatory cytokines, proteins that regulate inflammation, than fat stored just under the skin. The scientists suspect that constant exposure of inflammatory proteins produced by fat around the heart may accelerate the development of atherosclerosis.

For the analysis, the researchers measured the volume of pericardial fat in 159 study participants, who were 55 to 74 years old. Calcified coronary plaque was observed in 58 percent of participants.

Ding and colleagues divided participants into four groups based on the volume of pericardial fat. Those in the group with the highest levels of fat were almost five times (4.65) more likely to have calcified coronary plaque.

The researchers found that while the volume of pericardial fat was related to levels of calcified coronary plaque, body mass index and waist circumference were not related.

“Our findings suggest that local fat deposits, rather than total body fat, are most related to calcified coronary plaque,” Ding said. "Inflammatory mediators released from pericardial fat may promote inflammation in local coronary arteries and lead to coronary atherosclerosis."

Ding said he hopes to continue the research to learn more about whether the buildup of fat around the heart can be prevented.