Obesity causes inflammation of the tissue surrounding the heart and can trigger heart failure, researchers at John Hopkins have revealed.
For the study, the researchers conducted tests and examined the development of heart failure in an ethnically diverse group of nearly 7,000 men and women, between 45 to 84 years enrolled in the MESA study in 2000.
They found that of the 79 who developed congestive heart failure, 35 were physically obese, with the body mass index of 30 or greater.
And on average, the overweight participants were also found to have higher blood levels of interleukin 6, C-reactive protein and fibrinogen that are key immune system proteins involved in inflammation.
A near doubling of average interleukin 6 levels alone accounted for an 84 percent greater risk of developing heart failure in the study population.
"The biological effects of obesity on the heart are quite profound," said Dr. Joao Lima, senior study investigator.
"Even if obese people feel otherwise healthy, there are measurable and early chemical signs of damage to their heart, beyond the well-known implications for diabetes and high blood pressure," he added.
The researchers also found links between inflammation and metabolic syndrome. It's combined risk factors for heart disease and diabetes - high blood pressure, elevated blood glucose levels, excess abdominal fat and abnormal cholesterol levels, and particularly obesity increased the risk of heart failure two fold.
"Our results showed that when the effects of other known disease risk factors - including race, age, sex, diabetes, high blood pressure, smoking, family history and blood cholesterol levels - were statistically removed from the analysis, inflammatory chemicals in the blood of obese participants stood out as key predictors of who got heart failure," Lima added.
The findings revealed that, interleukin 6, a chemical that activates white blood cells and drives inflammation, was higher in obese patients. Moreover the average levels of C-reactive protein also tripled, thus boosting the risk of heart failure by 36 pct.
C-reactive protein levels are widely known to rise dramatically and speed up the early stages of inflammation when cells swell up with fluid, leading to widespread arterial damage.
One-fifth higher than average blood levels of fibrinogen, best known for its role in blood clotting but also a major player in muscle scarring, bumped up the risk of heart failure by 37 percent. When the inflammatory protein levels were included in the scientists' statistical analysis, the heightened risk from obesity disappeared.
"What this tells us is that both obesity and the inflammatory markers are closely tied to each other and to heart failure," said Hossein Bahrami, M.P.H., lead researcher.
The findings from the Multiethnic Study of Atherosclerosis (MESA), will be published in the May 6 issue of the Journal of the American College of Cardiology.