The results of the Multiethnic Study of Atherosclerosis (MESA) identifies "the biological effects of obesity on the heart" as a serious reason for 72 million overweight Americans to worry about their health.
Senior study investigator Joao Lima, M.D., says "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. Now there is even more reason for them to lose weight, increase their physical activity and improve their eating habits."
The development of heart failure of some 7,000 mean and women, aged 45 to 84 was followed by researchers conducting the MESA study, which started in 2000. To date, of the 79 participants who developed congestive heart failure 44% were obese with a body mass index (BMI) of 30 or more. They were also found to have higher blood levels of interleukin 6, C-reactive protein and fibrinogen, key immune system proteins involved in inflammation, than non-obese adults. An 84% greater risk of developing heart failure was accounted for by a near doubling of average interleukin 6 levels.
The links between inflammation and the combination of risk factors known as the metabolic syndrome alarmed the researchers from 5 U.S. universities.
The researchers from five universities across the United States also found alarming links between inflammation and the dangerous mix of heart disease risk factors known as the metabolic syndrome. Its 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—double a person’s chances of developing heart failure.
"More practically, physicians need to monitor their obese patients for early signs of inflammation in the heart and to use this information in determining how aggressively to treat the condition," says Lima, a professor of medicine and radiology at the Johns Hopkins University School of Medicine and its Heart Institute. "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," says Lima.
The study found that higher levels of interleukin 6 and a tripling of average levels of C-reactive protein in study subjects increased the possibility of heart failure by 36%.
What this tells us is that both obesity and the inflammatory markers are closely tied to each other and to heart failure," says lead researcher Hossein Bahrami, M.D., M.P.H. Bahrami, a senior cardiology research fellow at Hopkins, says "the basic evidence is building the case that inflammation may be the chemical route by which obesity targets the heart, and that inflammation may play an important role in the increased risk of heart failure in obese people, especially those with the metabolic syndrome."
Each year, nearly 300,000 Americans die from heart failure.
Source: Journal of the American College of Cardiology, May 6, 2008