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High BP + cold weather = heart attack

Last updated on: August 31, 2004 16:21 IST

A medical study says that if you suffer from hypertension, the primary symptom of which is high blood pressure, you have a 62 per cent higher chance of heart attack if the temperature so much as slips 5C. And if you live in a region where the temperature is lower than -4C (24.8F), your chance of suffering a heart attack has just doubled.

The moral of the story: those who are vulnerable to heart attacks should take care in cold weather and watch out for sudden temperature changes.

The study also found that in southern Asia, incorporating India, and in the the Middle East and Africa, people suffered heart attacks 10 years earlier than elsewhere. And, more than 80 per cent of the heart attacks occurred in low and middle-income countries.

Smokers have a threefold risk of heart attack compared to non-smokers, the study reported, and the risk is 80 per cent lower for non-smokers who consumed fruits and vegetables regularly, exercised three times a week and drank a little alcohol.

The two-year study was conducted among 700 people admitted to a hospital in France, and the findings were presented by Yves Cottin and Marianne Zeller of the University of Dijon at the European Society of Cardiology's meeting in Munich, Germany, on August 29.

The study, to be published in the medical journal The Lancet, involved more than 29,000 people in 52 countries, and took 262 scientists more than a decade to complete. The Lancet editor in fact, called it the 'most robust study' on the risk factors of heart disease ever conducted.

While it is well known that risk of heart attack is heightened in cold weather because of the constriction of blood vessels, this is the first study to document how change in weather increases the chance of heart attack in those with high BP.

Cold weather not only increases blood pressure, it also causes the blood to become thicker and hence more likely to clot. During winter, cholesterol levels are also higher, and respiratory infections could lead to inflammation that further contributes to the rupture of artery-clogging plaque.

Hailing the finding as 'good news', one of the researchers involved in the study, Salim Yusuf, professor of medicine at McMaster University in Ontario, Canada, was quoted as saying: "This convincingly shows that 90 per cent of the risk is predictable. It means we can do something about it."

Further, just two factors -- abnormal ratio of bad to good cholesterol, and smoking -- accounted for two-thirds of the risk of heart attack. And in a piece of good news for tipplers, regular consumption of small amounts of alcohol was actually found to reduce the risk. Other causative factors for heart attack was high blood pressure, diabetes, abdominal obesity, stress, and failure to eat fruit and vegetables, or exercise daily.

Yusuf said among the unexpected findings dug out by the study was the importance of psychological stress -- triggered off by factors like tension at home or work, financial problems, etc -- as opposed to physical stress, in causing heart attack.

Another important finding was that the causes of heart attack were the same in every region and race. Differences along gender lines, observed in the West, applied to other parts of the world too, Yusuf said. While men usually get heart attack at about the age of 57, for women it was 65.

A Correspondent