English Transcript

Cập nhật 03/09/2008 17:12:25

A long-term international study has found a link between a faster heart-rate and the risk of a heart attack. Cardiologists spent nearly four years studying patients all over the world, including Australia, and they found heart-disease patients with a pulse of more than 70 beats a minute are most at risk. The results were presented at a medical congress in Germany and published in the British medical journal, The Lancet.

Presenter: Anne Barker
Speakers: Sydney cardiologist Ben Freedman



BARKER: It might seem obvious, but it's never been shown until now that a faster than normal heartbeat significantly increases the risk of a heart attack in people who already have coronary disease. Cardiologists have studied 11,000 patients in 33 countries, including Australia. They found that those people with a rate of 70 beats a minute or more had a 30 percent greater risk of having a heart attack. Sydney professor of cardiology Ben Freedman has presented the findings at a conference in Munich.

FREEDMAN: It's quite possible that an increased heart rate puts an increased risk on the plaques - these are the narrowings that occur in coronary arteries, making it more likely for them to break open. I guess that's one of the theories. and it may just result in increased wear and tear at sites where there is a problem with cholesterol buildup.

BARKER: More importantly, the study showed that lowering the heart rate with the right drugs in turn reduced the risk of heart attack by more than a third.

FREEDMAN: The important thing is that by giving a drug that does nothing else but lower the heart rate, we were able to reduce heart attacks in these patients. I think it will influence the way we practice, and it certainly will lead to much greater emphasis on trials to determine the importance of heart rate, and I think after this study a new trial will be done in patients who don't have such a diseased heart. They may have coronary disease but their heart pump hasn't been damaged already and I think that's a much broader population where it could be very significant.

BARKER: Coronary heart disease is the largest single cause of death and the most common cause of sudden death in Australia. But researchers found that for all the multiple investigations performed on heart patients, too often the simple heartbeat is not even measured and Professor Freedman says it's now clear that heartbeat is highly significant.

FREEDMAN: We know that at least in the group who've already had a damaged heart, if they're on all of the best drugs and their heart rate remains elevated above 70, that further lowering it could prevent heart attacks and at least in the context of this study, if we have patients like this and treated 100 of them we might prevent two heart attacks in two years and reduce the need for bypass surgery or stenting by about 1 per 100.

BARKER: How common is a heartbeat over 70 beats a minute?

FREEDMAN: It should be stressed the study was done only on patients aged over 65 who already have heart disease.

BARKER: Professor Freedman says it'd be wrong to extrapolate that younger and otherwise healthy people with a naturally fast heart beat might be at risk of heart attack later in life

FREEDMAN: This may not be such a good predictor at young age, although at populations it does seem to predict over the age spectrum. but the risk of death obviously is much smaller in a population than if you've got a group of patients who've already got sick hearts.