Pulse Rate Changes Can Predict Trouble Ahead

A study in French male civil servants – policemen, aged 42 to 53 – has produced an interesting result. It’s reported in the European Heart Journal, online. If mild mental stress caused an increase in heart rate, the man was at increased risk of dying unexpectedly from a heart attack. That’s a bit of a shock! Many of us get a faster heart rate when under mild stress conditions . . .

The data came from 7,746 French policemen participating in the Paris Prospective Study I. Heart rates were measured at rest and under mild mental stress - the stress consisted of preparation prior to a bicycle exercise test. During a 23-year follow-up period there were 81 sudden cardiac deaths, 129 non-sudden coronary deaths, and 1,306 deaths from other causes.

Heart rates increased during the mild mental stress, at an average of 9 beats a minute. When the participants were classified into three groups according to the size of their stress-increased heart rates, those in the group with the greatest increases (more than 12 beats a minute) had twice the risk of sudden cardiac death, compared with those in the lowest-increase group (less than 4 beats a minute). There was no such relationship between heart-rate increases and non-sudden coronary deaths. On the other hand, 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 those whose heart rate increased least on exercise.

Sudden cardiac death accounts for between 200,000 and 400,000 deaths in the USA each year. It’s likely that genetics plays a considerable role. In this study, the risk of sudden death increased nearly three-fold in men whose mother’s had died suddenly, and nearly ten-fold if both parents had died suddenly, compared with men whose parents had not died suddenly. They researchers believe the findings reflect changes in the balance between the sympathetic and parasympathetic nervous systems. They also point out that the results of this study may not be applicable to women.