French researchers have found a chaep and si,ple method of predicting if an induvidual is at greater risk of dying suddenly and unexpectedly from a heart attack or not.
In a study of 7746 French male civil servants, published in Europe's leading cardiology journal, the European Heart Journal, the researchers found that men whose heart rate increased the most during mild mental stress just before an exercise test had twice the risk of dying of a sudden heart attack in later life than men whose heart rate did not increase as much.
The study is the first to discover this association and since taking a patient's pulse is an easy and inexpensive procedure, it suggests a way of identifying people who may be at increased risk.
Professor Xavier Jouven, of the Hopital Européen Georges Pompidou (Paris, France), who led the research, said the findings have significant clinical implications.
"People who showed a higher heart rate increase with mild mental stress could be considered for additional investigations and for tailored preventive strategies, aimed in the first place at reducing the probability of heart disease," he said.
Prof Jouven and his colleagues examined data from the Paris Prospective Study 1 of 7746 Frenchmen, aged 42-53, employed by the Paris Civil Service as policemen. The men were given health examinations between 1967-1972, including electrocardiograms and physical examinations.
Their resting heart rate was measured, and then it was measured in the few minutes just before they took part in a bicycle exercise test, while they were sitting on the bike; this was the time when the researchers considered the men to be under mild mental stress in preparation for the exercise stress test. Their heart rate was measured during the exercise and afterwards during the recovery period.
During an average 23 years of follow-up there were 1516 deaths including 81 sudden deaths as a result of a heart attack. The risk of sudden death from a heart attack increased with an increase in heart rate during mild mental stress.
After adjusting for confounding factors such as smoking, age, weight, physical exercise, cholesterol levels and diabetes, the researchers found that men who had the highest increase in heart rate during mild mental stress (increasing by more than 12 beats a minute) had twice the risk of death compared to men who had the lowest increase in heart rate (an increase of less than four beats a minute).
Conversely, men who had the highest increase in heart rate during the exercise test itself, had less than half the risk of sudden death compared with the men whose heart rate increased the least during the exercise test.
Further analysis showed that, in fact, there were no sudden deaths from heart attack amongst the 440 men who increased their heart rate the least during mild mental stress and the most during the exercise test. On the other hand, the highest proportion of sudden deaths were among the men who increased their heart rate the most during mild mental stress and the least during exercise - 14 out of 471 men.