Previous research has shown that emotional and physical stress can tax the hearts of both cardiac patients and healthy individuals. Working patients wearing implantable cardioverter-defibrillator ICDs are more likely to experience a rapid heartbeat on Mondays, for instance, and medical interns are more likely to have abnormal heart rhythms while they are on call.

What is an ICD?

The medical device, also known as an implantable cardioverter-defibrillator (ICD), is placed in the heart of a patient with an abnormal heart rhythm. The device detects heart rhythm abnormalities, and releases an electric impulse to stabilize the heartbeat. These abnormalities can lead to sudden death if normal heart rhythm is not restored.

To investigate emotional and physical triggers of abnormal heart rhythms, or arrhythmias, in a group of patients with ICDs, a team of researchers followed 240 people over 3 years.

What circumstances lead to an abnormal heart rhythm?

• Feelings of anger: Anger increased the risk of needing a shock to restore normal heart rhythm. Anger was the cause 15 percent of the time; patients reported that they had been arguing, gambling, driving or had just heard bad news when the shock was delivered.

• Other emotions: Emotions such as anxiety, sadness, happiness or feelings of being in control or challenged did not affect the risk of arrhythmia.

• Physical activity: Patients were also more likely to receive a shock when they were walking, engaging in physical activity at work or exercising. The researchers heavily emphasized, however, that low-level, carefully monitored physical exercise is definitely beneficial to these patients.

Circulation October 1, 2002;106