The excessive increase in heart rate during a stress doubles the risk of subsequent cardiac arrest

Xavier Jouven and his colleagues of the Center for Cardiovascular Research in Paris (Inserm Unit 970) have uncovered a simple and economical method to predict who is at increased risk of sudden death by heart attack. Their work appears in the journal European Heart Journal.

The researchers followed 746 officials french 7 males and found that men whose heart rate was most increased at a slight stress before a test effort, showed twice as likely to succumb later d a heart attack than men whose heart rate had not increased as much. This is the first study to highlight this association. "And as measuring the pulse of a patient is a simple and economical, it could help identify people at high risk," say the authors. "The people who have a strong increase in heart rate during a mild stress could be subjected to tests and prevention strategies to measure could be proposed to reduce the likelihood of heart disease," says Xavier Jouven who led the research.

Sudden death by cardiac arrest is a major public health problem with 40 000 cases per year in France: In the 27 European Union countries, it has caused 486 000 deaths in a population of 497 million people. Less than 5% of victims of heart attacks are resuscitated successfully. Accordingly, providing a means to identify as early as possible those at very high risk, in a general population in healthy, would be a huge step forward for the prevention of some of these deaths.

Xavier Jouven and his colleagues examined data from the Paris Prospective Survey on I 7 746 french men aged 42 to 53 years, employed as police officers to the Prefecture de Police de Paris. The subjects passed medical examinations between 1967 and 1972, including electrocardiograms and clinical and biological shoots. Their heart rate was measured at rest, then again a few minutes before a test effort on bicycle. The researchers considered that this time - just before the effort, once seated on the bike, men were subject to what they called a slight mental stress associated with the apprehension test of effort. Their heart rate was measured during exercise and then during the recovery phase.

During the 23 years of follow-up on average 1 516 deaths were recorded, including 81 sudden deaths following a heart attack. The risk of sudden death by cardiac arrest was even more important than the increase in heart rate during mild mental stress was high. After taking into account the usual cardiovascular risk factors such as smoking, age, body mass index, physical activity, cholesterol and diabetes, researchers found that men whose increase in heart rate was most important in light of mental stress (increase of more than 12 beats per minute) had a mortality risk twice as high as men whose heart rate increase was the most low (increasing from less than 4 beats per minute).

Conversely, men whose heart rate increase was the highest during the test effort itself presented a risk of sudden death cut by more than half compared to men whose heart rate was increased less during the test effort.

Further tests have revealed that sudden death by cardiac arrest had occurred among the 440 men whose heart rate had the least increase during mild mental stress and the greatest increase during the test effort. In contrast, the highest proportion of sudden deaths was found in men whose heart rate had risen slightly during the mental stress and increased less during exercise (14 out of 471 men).

"This study shows that the increase in heart rate during mild mental stress before the effort is a variable strongly predictive of sudden death. These results could have implications in clinical practice. Few medical tests are simple and economical to obtain large scale in the population that increase heart rate to stress. Taking the pulse of a person is a medical procedure practiced for thousands of years as part of clinical examination and our study shows that this can be used as a prognostic marker. These results contribute to a better understanding of the mechanisms of sudden death, "he Jouven.

Xavier Jouven and his colleagues argue in this case as an effect related to the interaction between the vagus nerve (freinateur and important component of the autonomic nervous system controls the unconscious functions of the body such as heart beat) and the activation of sympathetic system (in particular, accelerating the increase in heart rate, dilation of blood vessels in their muscles and constriction in the skin and intestines).

Researchers state that this study focused only on men, different results could be observed among women and that this should be further research in the future.

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