Heart rate link to heart attacks (by Mind Your Body of the Straits Time dated 14 Jan 2010)

A rapid heartbeat could increase your chances of suffering a fatal heart attack and this is more so for women, according to a new study. So regular workouts could be beneficial for them.

Researchers from Norway, who were involved in a study on more than 50,000 healthy adults over 20 years, found that with each increase of 10 beats per minute in resting heart rate, a woman's risk of dying from a heart attack climbed by 18 per cent up to the age of 70 years. For men, the risk rose by 10 per cent.

A healthy heart beats about 60 to 70 times a minute, with some normal variation on either side.

If the rate exceeds 80 for an extended period, doctors start to worry - that is, if they notice, because an elevated pulse may go undetected in otherwise healthy people, said one of the researchers, Javaid Nauman of the Norwegian University of Science and Technology in Trondheim.

High blood pressure, high cholesterol levels and diabetes are well-known risk factors for heart disease but, so far, heart rate has been overlooked, experts said.

'It's important to draw attention to heart rate as a cause of heart attack," Dr Malcolm Arnold, a University of Western Ontario cardiologist, told Reuters Health. He was not involved in the new study but said its large number of participants made it stand out.

According to Mr Nauman and his colleagues, their study, published in the Journal Of Epidemiology And Community Health, is the first to examine the combined effect of pulse and exercise on fatal heart attacks. For the analysis, they selected only people who did not have known heart disease.

At the outset of the study, the participants filled out questionnaires about their lifestyle and general health and scientists measured their heart rates and a few other physiological parameters.

When the study ended, more than 10,000 of the participants had died, some 40 per cent due to heart disease. Overall, men who had a resting heart rate above 100 beats per minute were 73 per cent more likely to die from a heart attack than men whose heart rate lay within the healthy range.

For women whose resting heart rate was above 100 beats per minute, the risk of a fatal heart attack increased by 42 per cent, and in those younger than 70 years, it more than doubled.

People who exercised, however, had a considerably lower resting heart rate than those who were more sedentary.

In women, those who reported higher levels of physical activity had a lower risk of dying from heart disease, irrespective of their resting heart rate. Among the most active, even a heart rate above 87 beats per minute did not lead to a significant increase in heart attacks.

'The most promising thing that we find is that you can keep a check on your resting heart rate by engaging in physical activity," Mr Nauman, an exercise physiologist, told Reuters Health, noting that this would reduce the risk of a heart attack.

He said the lower heart rate in active people was likely due to exercise's balancing effects on the autonomic nervous system, which can crank our heart rate up and down.