Obesity Alone Raises Risk of Fatal Heart Attack, Study Finds
MONDAY Feb. 14, 2011 -- Obese men face a dramatically higher risk of dying from a heart attack, regardless of whether or not they have other known risk factors for cardiovascular disease, a new study reveals.
The finding stems from an analysis involving roughly 6,000 middle-aged men, and it suggests that there is something about carrying around excess weight that contributes to heart disease independent of risk factors such as high blood pressure, diabetes, high cholesterol and arterial disease.
What exactly that something is, however, remains unclear, although the researchers suggest that the chronic inflammation that typically accompanies significant weight gain might be the driving force behind the increased risk.
"Obese, middle-aged men have a 60 percent increased risk of dying from a heart attack than non-obese middle-aged men, even after we cancel out any of the effects of cholesterol, blood pressure and other cardiovascular risk factors," noted study author Jennifer Logue, a clinical lecturer of metabolic medicine with the British Heart Foundation's Cardiovascular Research Centre at the University of Glasgow, in Scotland. "This means [that] obesity itself may be causing fatal heart attacks through a factor that we have not yet identified."
Logue and her colleagues report their observations in the Feb. 15 online issue of Heart.
To explore the subject, the authors spent nearly 15 years tracking 6,082 male patients who were diagnosed with high cholesterol but had no history of either heart disease or diabetes.
Over the study period, the research team noted 214 heart disease fatalities, along with another 1,027 heart attacks and/or strokes that did not result in death.
The team confirmed the well-established theory that being obese is linked to a greater chance for having all of the classic risk factors linked to heart disease.
That said, even after ruling out relevant variables such as age and smoking history, the risk of death among obese men -- those with a body mass index (BMI) between 30 and 39.9 -- was still 75 percent higher than it was for non-obese men.
What's more, even after also accounting for risk factors such as high blood pressure and diabetes (as well as medication history), the chance of experiencing a fatal heart attack was 60 percent greater among obese men, as compared with non-obese men.
The one caveat: in and of itself, being obese was not linked to a higher risk of experiencing a non-fatal heart attack or stroke.
Logue cautioned that further research is needed to confirm the findings, and to uncover the exact mechanism by which obesity itself is a risk factor for fatal heart attacks.
"Possible reasons include particular chemicals that the fat cells are releasing. Or perhaps it is related to the fact that obese people tend to have larger hearts to cope with the additional stress of their larger size, and this already stressed heart does not manage to continue to work during a heart attack," she said.
"However, it certainly makes me think that we cannot just treat cholesterol, blood pressure and diabetes in obese men without also considering their weight," Logue added. "We need to find easier and more effective ways to help people lose weight and find out if losing weight can help reduce the risk of fatal heart attacks. We also need to dedicate far more resources to preventing obesity in the first place."
Dr. Gregg C. Fonarow, a professor of cardiology at the University of California, Los Angeles, said that the current study "provides further evidence as to why there needs to be global efforts to prevent and treat obesity though lifestyle modification."
"While obesity is associated with elevations in blood pressure, increased risk of diabetes and abnormal lipid levels, it has been less clear whether the increased risk of mortality associated with obesity can be entirely explained by these well-established cardiovascular risk factors or whether other factors related to obesity may also be contributing to excess mortality risk," he noted.
Dr. Murray A. Mittleman, director of the Cardiovascular Epidemiology Research Unit with the Beth Israel Deaconess Medical Center, Harvard Medical School in Boston, agreed.
"It's not surprising that not all of the risk can be explained by traditional risk factors," he said. "But no one study is going to definitively answer the question as to what other mechanisms for risk might be. So the primary issue would still continue to be working towards overall weight reduction, to reduce the risk for all of the pathways that we already know go along with obesity."
For more on obesity and heart disease, visit the American Heart Association .
Posted: February 2011