Innumerable studies have laid out the dire health consequences of obesity, but there’s one situation where being overweight seems helpful: coronary angioplasty.

Analysis of data from the New York State Angioplasty Registry indicates that people who are moderately to severely obese are less likely than others to suffer major adverse events or to die after undergoing catheter-balloon procedures to open clogged coronary arteries.

At the Weill Cornell Medical College in New York, Dr. Robert M. Minutello and colleagues studied the impact of body mass index (BMI) - a measure of weight in relation to height - on in-hospital outcomes after angioplasty by reviewing data on more than 95,000 patients.

For the study, published in the American Journal of Cardiology, patients were classified according to BMI as being underweight, healthy weight, overweight, moderately obese, severely obese, or very severely obese.

The researchers report that a U-shaped relationship was found between body mass index and risk of major adverse coronary events. In-hospital deaths were higher among underweight and very severely obese patients than among the others.

Furthermore, underweight and severely obese patients were at greater risk for the combination of death, heart attack, or emergency surgery than patients with moderate or severe obesity.

Minutello’s team suggests that the poorer outcome in underweight patients is not so surprising, but the reasons why overweight patients fare well is more puzzling. One possibility is that these patients may have larger blood vessels, making the procedure easier, but that is not proven.

All in all, the researchers call for “further studies to determine the factors responsible for the evidently protective effect of moderate and severe obesity.”

SOURCE: American Journal of Cardiology, May 15, 2004.