TUESDAY, April 7 (HealthDay News) -- Swedish studies add heart failure to the list of cardiac problems linked to overweight and obesity.

"The take-home message is that body-mass index, however we measure it, is associated with the risk of heart failure," said Emily B. Levitan, a research fellow at the Cardiovascular Epidemiology Research Unit of Beth Israel Deaconess Medical Center in Boston. She is lead author of a report in the April 7 issue of Circulation: Heart Failure.

That report gave results of two studies, one of 36,873 Swedish women and one of 43,487 Swedish men, who were followed for six years and tracked for body-mass index (BMI) and the incidence of heart failure. Overweight is defined as a BMI between 25 and 30, and obesity as a BMI of 30 or higher. By that definition, 34 percent of the women in the study were overweight and 11 percent were obese, while 46 percent of the men were overweight and 10 percent were obese.

A gender difference emerged from the study of waist circumference in men and women. In women, BMI was associated with heart failure risk only among those who were fattest at the waist. In men, each one-point increase in BMI was associated with a 4 percent increase in heart failure risk, no matter what the waist size.

These are several possible explanations for the difference, Levitan said. "One is that the type of heart failure that men and women get is different," she said. "Another is that overall body size is more important than body shape in men."

Whatever the reason, the lesson for both men and women is that weight control can reduce the risk of heart failure, Levitan said.

"For many years, at least among physicians, we were taught that obesity in and of itself was not a risk factor for heart failure," said Dr. Muriel Jessup, professor of medicine at the University of Pennsylvania, and a spokeswoman for the American Heart Association. "We knew it to be a risk factor for coronary disease, but heart failure is a separate condition."

Coronary disease is blockage of heart arteries that can eventually cause a heart attack. Heart failure is the progressive loss of the heart's ability to pump blood.

While many patients who have heart failure also have coronary disease, this is not always so," Jessup said.

"These studies look at the impact of obesity and go a long way toward helping us understand why that is so," Jessup said.

The study, done among the ethnically homogeneous Swedish population, "can help us get insights into why some racial groups have early heart failure," she said. A study reported last month that heart failure tends to occur at least a decade earlier in blacks than in whites, Jessup noted.

While the incidence of coronary disease among Americans has been going down, heart failure has increased, she said. One reason is that methods of preventing and treating coronary disease have improved, Jessup said. "People don't die of myocardial infarction [heart attack] but go on to have heart failure," she said.

The link between excess weight and heart failure "is another reason for people to watch their weight and another signal to physicians to be more aware of following their obese patients," Jessup said.

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• Heart Failure
• Obesity