Friday, April 1, 2011
Obese with strong heart beats those thin and weak
NEW YORK (Reuters Health) - For overweight people with heart disease, improving their physical fitness could pay big dividends.
A new study has found that fitness, not body weight, is a more important predictor of whether people with clogged blood vessels in their heart will die in the relatively near term.
Being overweight, or even obese, but having a heart that could tolerate heavy exercise was markedly better than being a lean person who panted from walking up a hill.
Not surprisingly, the study also showed that obese heart patients who were least physically fit, and those with large amounts of fat concentrated around their hips and abdomen, were much more likely to die during the 14-year study period compared to their fitter, more slender peers. The combination of poor fitness and that kind of so-called "central obesity" was even more dangerous, raising the risk for death roughly sevenfold, the researchers said.
"The bottom line here is that fitness modulates the prognosis in patients with coronary artery disease according to their body weight," study leader Dr. Francisco Lopez-Jimenez, a heart specialist at Mayo Clinic, in Rochester, Minn., told Reuters Health. "To have a low fitness and to have central obesity seems to be a pretty bad combination."
For the new study, published in the American Heart Journal, Dr. Lopez-Jimenez and colleagues studied 855 men and women enrolled in a cardiac rehabilitation program. In the past, all of them had either had heart attacks, or bouts of severe chest pain related to heart problems. Some had undergone medical or surgical procedures to help unclog the blood vessels in the heart.
To assess patients' fitness, doctors had them walk on treadmills. They were each assigned a score based on the distance they could walk, and their ability to take in oxygen while exercising - both key aspects of physical fitness.
The researchers used body-mass index - a ratio of height to weight - to determine whether patients were overweight or obese.
Patients who were fit and relatively thin had the lowest odds of dying in the study period and constituted a "control" group. Fit but overweight patients were about twice as likely to die, while those who were fit but obese had three times the risk of death compared to the fit and thin control group.
Things got more complicated for the unfit. Patients with poor fitness scores who were overweight were nearly 7 times more likely to die during the study compared to the control group. But normal-weight people who were unfit were nearly 10 times more likely to die, the researchers found.
In other words, as long as a person with heart disease stays active, being obese-at least according to their body mass index-does not seem to make their prognosis worse. On the other hand, having too much abdominal fat is a problem even for people who can withstand a lot of exercise.
"You are better off if you are fit, and you are better off if you have a shorter belt," said Eric Ravussin, an obesity expert at the Pennington Biomedical Research Center in Baton Rouge, LA.
Ravussin offered several explanations for why obesity did not seem to have the impact one might expect. Obese people typically go to the doctor often, and thus are more likely to be tested, and treated, for high cholesterol, a leading risk factor for heart attacks and strokes, he said. The new study did not look at how many cholesterol-lowering medications patients were taking.
Compared to thin people, the obese have more energy reserves to help them weather serious illnesses, Ravussin noted. Also, studies have shown they appear to be better able to suppress inflammation linked to heart and vessel damage - although the reasons for that aren't clear.
Whatever the case, Lopes-Jimenez said, the lesson for patients is clear: try to improve your physical fitness. "It is much easier to become fit than it is to become slim," he said. "Anybody who has gone into an exercise program would agree with that."
SOURCE: Reuters, Adam Marcus 3/31/11: bit.ly/i25TCj American Heart Journal, March 2011.