WEDNESDAY, May 9 (HealthDay News) -- A "spare tire" around the midsection raises the odds of sudden cardiac death in obese people, a new study finds.

A larger waist-to-hip ratio matters even more than body-mass index when it comes to sudden cardiac death risk, said study researcher Dr. Selcuk Adabag, an associate professor of medicine at the University of Minnesota in Minneapolis. Body-mass index is a measure of weight relative to height used to determine normal weight and obesity.

Obesity, a moderate risk factor for sudden cardiac death, and apple-shaped bodies often go hand in hand.

"The significance of this study is that it shows that abdominal obesity is an independent risk factor for sudden cardiac death, even after accounting for factors such as diabetes, hypertension and coronary heart disease," said Adabag, who is also a cardiac electrophysiologist at the Veterans Administration Medical Center in Minneapolis.

Adabag was scheduled to present the findings Wednesday at the annual meeting of the Heart Rhythm Society in Boston.

Sudden cardiac death is responsible for more than 250,000 deaths in the United States each year, according to the Centers for Disease Control and Prevention. It is defined as death that occurs within an hour of initial symptoms. Besides obesity, risk factors include coronary heart disease and heart rhythm problems.

For the study, Adabag looked at the records of more than 15,000 people with an average age of 54 from four U.S. locales who were enrolled in the Atherosclerosis Risk in Communities Study. Over 13 years, more than 300 of the participants experienced sudden cardiac death.

After Adabag took into account age, sex, race, education, smoking status and family history of heart disease, he found that body-mass index, waist circumference and waist-to-hip ratio all were linked with sudden cardiac death.

"I expected there would be some relationship with all [those factors] measured," he said.

But when he factored in co-occurring conditions such as diabetes, high blood pressure, heart failure and a high LDL, or ''bad," cholesterol, among other problems, only the elevated waist-to-hip ratio still was linked with sudden cardiac death.

Although the reason people with apple-shaped bodies have higher risks than those with pear-shaped bodies isn't clear-cut, Adabag speculates that where fat is stored is important for heart risks.

"Fat in the abdomen spews inflammatory substances," he said. Inflammation is linked with heart problems.

Dr. Suzanne Steinbaum, a preventive cardiologist and director of Women and Heart Disease at Lenox Hill Hospital in New York City, said the findings are interesting.

"We have an understanding that an elevated waist-to-hip ratio is associated with conditions like diabetes and high blood pressure," Steinbaum said. "But what we never really appreciated before was the association with sudden cardiac death."

A waist-to-hip ratio of more than 0.8 for women and 0.95 for men is considered unhealthy. A person with 35-inch hips and a 35-inch waist, for instance, would have a ratio of 1, which is undesirable.

How do you improve your waist-to-hip ratio? "The usual way that we prevent obesity: exercise and diet -- a healthier lifestyle," Adabag said.

"Exercise is so crucial," Steinbaum said. Those with a pot belly, she added, may be eating too many simple carbohydrates, such as those found in processed sugary foods.

In the United States, two-thirds of adults and one-third of children reportedly are overweight or obese, according to background information included in Adabag's study.

While the study uncovered a link between abdominal fat and heart risks, it didn't prove a cause-and-effect relationship.

Data and conclusions presented at meetings should be considered preliminary until published in a peer-reviewed medical journal.

More information

To learn more about sudden cardiac death, visit the U.S. National Heart, Lung, and Blood Institute.