Website: http://www.americanheart.org

NEW ORLEANS, Nov. 14, 2000 – An unusually heavy meal may increase the risk of heart attack by about four times within two hours after eating, according to a study presented today at the American Heart Association’s Scientific Sessions 2000.

Researchers say this finding indicates that eating a heavy meal may act as a trigger for heart attack in much the same way as extreme physical exertion and outbursts of anger might – especially in someone who has heart disease.

"To the best of our knowledge, this is the first time that overeating by itself has been shown to increase the risk of heart attacks," says lead author Francisco Lopez-Jimenez, M.D., M.Sc., a cardiology fellow at Brigham and Women’s Hospital in Boston. "We hope that the results of our study will help convince people to be more cautious about eating exceptionally heavy meals, especially for people who have coronary artery disease or have suffered a previous heart attack."

The researchers questioned 1,986 male and female patients about the meals they had eaten just prior to their heart attacks. Of these, 158 had consumed a self-described heavy meal within 26 hours beforehand, and 25 had eaten a big meal during a two-hour "hazard period" preceding the attacks. The time of day when the meal was eaten had no apparent effect on the association.

While the study data covered the 26-hour period before the onset of heart attacks, Lopez-Jimenez says the most critical time was the two hours immediately preceding the onset of heart attack symptoms.

Although there is a distinct difference between risk factors that develop over a lifetime – such as obesity, high cholesterol, hypertension and advanced age – and those that act as sudden triggers for a heart attack, both are potentially dangerous, he adds.

There are several ways that a heavy meal can adversely affect the heart. Eating and digesting food releases many hormones into the bloodstream. Those substances increase the heart rate and blood pressure, and may increase the substances that help form clots. The temporary rise in blood pressure increases the oxygen requirements and creates an extra burden on the heart. High blood pressure may also rupture cholesterol plaques in the arterial wall, triggering the formation of a clot that can block a blood vessel, triggering a heart attack or stroke.

Another mechanism could be that a high-fat meal impairs the function of the endothelium, the inner lining of the arteries, by a direct effect of fatty acids and other fats in the bloodstream. The rise in insulin, a substance that helps the body burn energy, after a large meal may also affect the inner lining of the blood vessels that lead to the heart. An increase in insulin levels in the blood decreases the normal relaxation of the coronary arteries.

Other researchers participating in the study include Murray A. Mittleman, M.D., D.P.H.; Malcolm Maclure, Ph.D.; Jane B. Sherwood, R.N.; James E. Muller, M.D., and Geoffrey H. Tofler, M.D.