March 22, 2004 -- Anger, frustration, and other mental stress can trigger abnormal heart rhythms that may lead to sudden death, new research shows.
In the first study of its kind, a group of researchers has demonstrated that mental stress alone can provoke these dangerous heart rhythms. Their study appears in the April 13 issue of Circulation: Journal of the American Heart Association.
Certain irregular heart rhythms (or arrhythmias) put people at high risk for sudden death. The unpredictable nature of these arrhythmias has posed a major challenge in preventing sudden cardiac death, writes researcher Willem J. Kop, PhD, with the Uniformed Services University of the Health Sciences in Bethesda, Md.
In recent years, however, doctors have been able to more clearly identify people who are at risk for these arrhythmias -- as well as the activities that can trigger sudden cardiac death.
For example, researchers have identified an abnormal heart rate pattern called T-wave alternans (TWA) that are proving to be a new marker of heart rhythm instability that precedes potentially dangerous arrhythmias. They can be measured via electrocardiogram (EKG).
This heart rate pattern has been identified in people with implantable cardiac defibrillators (ICDs) and heart attack survivors during exercise testing.
Other studies show that periods of emotional upset -- such as anger -- can trigger life-threatening arrhythmia and other heart irregularities.
This study is the first to look at TWA patterns during times of severe mental stress.
In one mental stress test, the volunteer was asked to give a four-minute speech about a recent anger-provoking incident. The other test was a challenging mental arithmetic test; each volunteer was interrupted and urged to improve performance throughout the test.
The exercise test involved 25 minutes of bicycling; volunteers were stopped before they developed any heart-related problems.
During both the mental stress and exercise tests, the defibrillator patients all had increases in the abnormal TWA heart rhythm pattern than the healthy people did.
However, there was one significant difference: Mental stress provoked in the defibrillator patients' a dramatic increase in the abnormal heart rate pattern at a significantly lower heart rate than did the exercise.
This is important, Kop says, because exercise testing has been the traditional method used to measure risk for unstable heart rhythms. This study showed that exercise testing may miss some patients at risk for serious arrhythmias; mental stress can provoke a potentially fatal instability in heart rhythm in people who have heart disease at much lower heart rates than is caused with exercise testing.
If the findings can be replicated in a larger study, they may affect the evaluation and management of many patients, especially older and more sedentary heart patients, and to those with heart disease, he says.
Other studies show that anger and mental stress create arrhythmias that trigger an ICD discharge, Kop points out.
SOURCE: Kop, W. Circulation: Journal of the American Heart Association, rapid access issue, April13, 2004; vol 109.