Apple Shape Predicts Heart Attack Risk Better than BMI

A pot belly increases the risk of a Heart Attack - even if the rest of the physique is as skinny as a beanpole.

The person with that build would have a low body mass index (BMI). Based on that, the person would be classified as having a low Heart Attack risk. But, insist researchers here, it's really the ratio between the distance around that pot belly and the circumference of the hips that tells the tale of risk.

If the waist-to-hip ratio is high, irrespective of the BMI, the risk of a Heart Attack is increased, Arya Sharma, M.D., and Salim Yusuf, M.D., of McMaster University here and colleagues reported in the Nov. 5 issue of The Lancet, based on a new analysis of the Interheart study data.

"If you have more of a waist line than a hip line, then you're at risk," Dr. Sharma said in an interview. He is director of the Canadian Obesity Network.

In general, he said, people are regarded as being at low risk if their waist-to-hip ratio is less than 0.85 for women and 0.9 for men. The waist is measured between the top of the hip bone and the lower edge of the rib cage without clothing; the hips are measured over light clothing at the widest part of the buttocks.

Dr. Sharma and colleagues showed last year with Interheart data that abdominal Obesity accounts for about 90% of the risk for myocardial infarction around the world, with eight other risk factors - including cigarette smoking, diabetes, poor diet, and lack of exercise - accounting for the rest.

Now, Dr. Sharma and colleagues reported that of several measures of Obesity, including BMI, the best predictor of Heart Attack risk is the waist-to-hip ratio.

"It just reinforces what we've known for a long time - the whole apple-shaped, pear-shaped thing," he said. "What's new here is that BMI falls right out of the equation."

"If you just look at crude data, there is some association, but that's just because people with high BMI tend to have a high waist-to-hip ratio," he said. "If you correct for other risk factors, BMI essentially gives you no information."

On the other hand, he said, there's a smooth increase in risk with increasing waist-to-hip ratio, regardless of BMI.

The Interheart study - a case-control analysis of acute myocardial infarction - involved 27,098 participants in 52 countries, the investigators reported.

The study had three key findings, he said: