Bouts of anger can create electrical changes in the heart that may be dangerous to some heart disease patients, a study published Monday suggests.

The study, of 62 patients with heart devices called implantable cardioverter defibrillators (ICDs), found that anger-induced changes in the heart’s electrical activity predicted patients’ risk of suffering a serious heart-rhythm disturbance over the next 3 years.

ICDs are implanted in people at high risk of cardiac arrest from ventricular fibrillation, an arrhythmia in which the heart begins to quiver chaotically and stops pumping blood to the body. It is quickly fatal unless an Electrical shock is delivered to the heart; ICDs automatically do this.

Past studies have found links between strong emotions and the risk of sudden death from cardiac arrest. Similarly, there is evidence that emotional stress can trigger ventricular fibrillation in people with an ICD.

“The most important finding from this study is that it tells us the mechanism by which anger and strong emotions may be linked to sudden death,” said lead researcher Dr. Rachel Lampert, of Yale University School of Medicine in New Haven, Connecticut.

“It tells us that yes, anger really does cause electrical changes in the heart,” she said in an interview.

Lampert and her colleagues report the findings in the Journal of the American College of Cardiology.

The researchers monitored 62 ICD patients’ heart activity as they underwent mental-stress tests in which they had to recall a recent incident that had angered them. They then followed the patients for 3 years, on average, to chart any instances of arrhythmia requiring an Electrical shock from the ICD.

Overall, Lampert’s team found, patients with greater anger-induced electrical changes in the initial heart tests were at greater risk of suffering an arrhythmia.

Among those with the highest levels of anger-triggered electrical changes, 40 percent required an ICD shock during the study period, compared with just 9 percent of patients whose heart activity had been less responsive during the stress tests.

ICDs are designed to prevent such arrhythmias from being fatal.

However, Lampert pointed out, the device shocks are painful, and the goal is to prevent serious arrhythmias in the first place.

No one knows yet whether better anger management might lower ICD patients’ arrhythmia risk. The Yale researchers are now conducting a study to look at that question.

The current findings also raise the possibility that testing for anger-induced electrical changes could help predict ICD patients’ future heart risks. Such tests, Lampert explained, could offer an alternative to traditional exercise testing, which many ICD patients are unable to manage.

“That’s an interesting possibility,” Lampert said, “but it’s not yet determined.”

SOURCE: Journal of the American College of Cardiology, March 3, 2009.