Higher Pre-Exercise Heart Rate Doubles Risk of Sudden Death
Researchers from France have found that higher heart rate before exercise is a strong predictor of the risk of sudden death from heart attack later in life. Professor Xavier Jouven, of the Hopital Européen Georges Pompidou (Paris, France), and colleagues found that merely taking a pulse before an exercise stress test is an inexpensive way to predict risk of sudden cardiac death. Men whose pre-exercise heart rate increased in response to mental stress had double the risk of sudden death.
"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," says Professor Jouven. Sudden death from heart attack is a major concern and accounts for 200,000-400,000 deaths annually in the US alone. Identifying risk of sudden death by awareness of pre -exercise heart rate could reduce deaths.
The study looked at 7746 French male civil servants. The men were followed for 23 years. The findings showed that men whose heart rate increased the most during exercise had less chance of sudden death from heart attack, compared to those whose heart rate increased the least. Additionally, the risk of sudden death from heart attack increased among men whose pre -exercise heart rate increased the most before stress testing. Among 440 men who did not have increased heart rate before testing, there were no sudden deaths.
Jouven says, "This study shows that the heart rate increase during a mild mental stress in preparation for exercise is a strong predictor of sudden death. These findings may carry significant clinical implications. Few measurements in medicine are as inexpensive and as easy to obtain in large general populations as to measure the heart rate difference between resting and being ready to perform an exercise test. Taking a person's pulse has been part of clinical examinations for thousands of years – the Chinese carried it out, for instance – and now our study shows it can be used as a prognostic marker. The results will contribute towards a better understanding of the mechanisms of cardiac death."
The researchers believe higher pre-exercise heart rate is related to vagal tone. The vagus nerve can control heart rate during a heart attack, providing protection. In the absence of heart rate control from the vagus nerve, sudden death is more likely during a heart attack.
Measuring pre-exercise heart rate, combined with early intervention for prevention of heart attack, could reduce sudden death. The researchers say the findings may be different for women, suggesting more research.
European Heart Journal. doi:10.1093/eurheartj/ehp160.