Any extra weight a heart risk, study says

Being even moderately overweight or obese increases a person's risk of developing heart failure, a serious condition in which the heart is unable to pump enough blood to supply the body's needs, according to data released yesterday from the long-running Framingham Heart Study.

The findings add heart failure to the long list of diseases and conditions to which obesity has been linked. For example, overweight or obese individuals are predisposed to developing high blood pressure, high cholesterol and diabetes, each of which also increases the risk of heart attack and of heart failure.

Previously, researchers were aware that severe obesity was an independent risk factor for heart failure, but the new data show that being even moderately overweight increases one's chances of developing the condition — and the more overweight someone is, the greater the risk. Obesity alone accounts for 14 percent of cases of heart failure in women and 11 percent in men, according to estimates in the study, which appears in today's issue of the New England Journal of Medicine.

Obesity "is almost a primordial risk factor," said Claude Lenfant, director of the National Heart, Lung and Blood Institute. "If you have it ... you are going to be pulled to all these problems, and eventually ... to heart failure."

Obesity has become epidemic in the United States in recent years, with 61 percent of adults classified as overweight or obese on the basis of their body mass index (BMI), a ratio of weight to height. At the same time, the incidence of heart failure has risen during the last quarter-century because of improved survival from heart attacks, the aging of the U.S. population and other factors. About 4.8 million Americans are living with heart failure, and the condition causes about 51,000 deaths annually.

The study "ups the ante for how much of a health risk it is to be obese," said David Cummings, an obesity researcher at the University of Washington.

Because heart failure develops gradually, it most commonly affects people over age 60. It can occur when the heart's muscle wall has been damaged, often by heart attacks, and cannot contract strongly enough to pump blood efficiently, or when the wall has become so stiff and thick that the heart does not fill sufficiently with blood between beats. Sometimes both problems contribute. Symptoms of heart failure usually include breathlessness when sleeping or lying flat, ankle swelling, difficulty breathing with minor exertion, a nighttime cough and a fast heart rate.

"It's a bad condition to have," said Ramachandran Vasan of Boston University School of Medicine, a senior investigator with the Framingham Heart Study and principal author of the new study. "Although we have excellent medications ... the general outcome is grim. The five-year survival is often less than 50 percent."

In the study, researchers monitored the characteristics, habits and long-term health of 5,881 residents of Framingham, Mass. Their average age was 55 at the start, and they were followed for an average of 14 years. Heart failure developed in 496 participants — 258 women and 238 men.

BMI can be approximated by multiplying weight in pounds by 703, then dividing by height in inches squared. A normal BMI is 18.5 to 24.9. Among study participants, overweight women (BMI between 25.0 and 29.9) had a 50 percent greater risk of heart failure than women of normal weight, and overweight men had a 20 percent greater risk than men of normal weight. In obese people of either sex (BMI of 30 or greater), heart failure risk was nearly twice that of normal-weight individuals.

Despite the sex difference in the results, "there is no indication that the overweight state or obesity has a different impact in women than in men," Vasan said. In both sexes, the data showed that heart failure risk increased steadily with greater degrees of overweight. Each increase of 1 in the BMI was associated with an increase in heart failure risk: 5 percent for men and 7 percent for women. The impact of overweight on heart failure risk was still apparent after statistical adjustment for other known risk factors such as age, smoking, high blood pressure and diabetes.