Prajapati Vishva Ashram

Causes of heart attacks vary by region
Massive study finds
some risk factors are more common
among certain populations....
By CAROLYN ABRAHAM
MEDICAL REPORTER
Canadian Globe and Mail: Monday, August 30, 2004 - Page A5

There's something about men and women of the Middle East that keeps high blood pressure from causing many heart attacks, even though their stress levels appear to be second only to North Americans'.

In Southeast Asia, high blood pressure has proven to be a stronger predictor of a heart attack than in any other region.

And while the rest of the world battles the bulge, the Chinese seem to boast the world's trimmest waistlines, with only 5.5 per cent of their heart attacks attributable to abdominal obesity, compared with a 64 per cent in Western Europe.

A massive new Canadian study may have found that the risk factors for heart disease are the same for all populations, but researchers say there is no question that some ethnic groups are more vulnerable to certain risks than others for genetic, cultural and socioeconomic reasons.

"Some risk factors are certainly more prevalent in some populations," said Sonia Anand, a contributor to the Interheart study and associate professor of medicine at McMaster University and Hamilton Health Sciences.

"But this can be explained by a number of factors, including multiple genes with small effects that make you more vulnerable."

Statistics already prove heart disease hammers certain populations, with Russia and Scotland near the top of the list and countries such as Japan and France at the bottom.

An earlier McMaster project looking at what kills Canadians found heart disease claims the lives of far more Europeans and South Asians than it does Chinese, who die more often of cancer, particularly gastrointestinal cancer.

Such numbers have left some patients, and even some doctors, with the impression that the Chinese enjoy a mysterious protection from the world's leading killer.

"You'll have a doctor say, 'I've got this patient, he seems low risk -- he's skinny and he's Chinese -- but he's had a heart attack. Explain that,' " Dr. Anand said.

"It may be that the Chinese do have a diet that protects them from the risk factors that cause heart disease, but no group is immune."

The Interheart study shows the greatest threats to the hearts of China come from high cholesterol, smoking, stress and a lack of fruits and vegetables. Other research suggests the Chinese may not always be spared 'the spare tire,' a pattern of weight gain prevalent among South Asians and Africans, and a leading cause of heart disease.

Although Chinese in Canada tend to weigh about 18 pounds less than Europeans or South Asians, Dr. Anand said, after living here five years the weight around their middles increases, particularly compared with people living in rural China.

One of the more striking findings of the Interheart study involved both Africa and the Middle East, where high cholesterol contributed to more heart attacks than any other risk factor. Those regions also had the highest number of men who suffered their first heart attacks at age 40 or younger.

The finding may point to a high-fat food problem. Yet the study also suggests that heart-disease sufferers in these regions, as in South America, eat more fruits and vegetables than any other populations in the world.

Alan Bernstein, president of the Canadian Institutes of Health Research, said future research will likely show that genes contribute to such puzzling trends in subtle, but significant, ways.

"If two people eat a high-fat diet, only one of them may develop heart disease because only one of them has the genes that makes that diet show up as abnormally high lipids," Dr. Bernstein said. "But if you eat well, this doesn't have to be the case. Genes are not necessarily destiny."

Study leader Salim Yusuf, a McMaster professor of medicine, noted that men in Africa and the Middle East may suffer heart attacks at younger ages because prevention strategies in those regions are not as advanced as they are in Western countries.

Eastern and Central Europe proved to be the only regions in the world where the incidence of heart disease could not be fully explained by the common heart-attack causes that the study found elsewhere.

But Dr. Anand explained that researchers have yet to take into account the cardiovascular impact of socioeconomic stress, which is likely to be a significant risk factor in countries of the former Soviet Union.

In the meantime, translating the findings of the Interheart study into public-awareness campaigns will not be simple.

It's unlikely, for example, that they can pitch the protective heart benefits of three alcoholic drinks a week to some Eastern cultures.

As well, Dr. Anand said, fighting abdominal obesity also means combating cultural assumptions such as, "If you can see three rolls of fat in a sari, that's a sign of wealth."

Studies show that heart attacks are associated with nine risk factors: smoking; lack of exercise alcohol; lack of fruits and vegetables in diet; hypertension; diabetes; abdominal obesity; high levels of bad cholesterol and stress. The degree to which each factor contributes to heart attacks can vary from region to region. Here are a few examples:

In North America, abdominal obesity explains 60% of heart attacks; at the same time, 52% are associated with stress.

In Africa, abdominal obesity explains 58% of heart attacks, but only 11% are associated with a lack of exercise.

In Australia, smoking explains 45% of heart attacks, and 11% are associated with a lack of fruits and vegetables.

In Southeast Asia, high levels of bad cholesterol explain 68% of heart attacks, but ony 21% are associated with diabetes.