THURSDAY, May 5, 2005 (HealthDay News) -- The adrenaline released in outbursts of anger may place individuals with a history of irregular heartbeat at heightened risk for cardiac arrest, a new study suggests.
Researchers at Yale University report that arrhythmias provoked by hostility are more hazardous than those associated with less volatile emotions.
"You don't want to have any arrhythmia, but some are much more dangerous than others," said Dr. Matthew M. Stopper, the study's first author and an internal medicine specialist at Yale University School of Medicine, in New Haven. "Arrhythmias associated with anger tend to be less stable, which generally means that they are more lethal."
His team were to report their findings Thursday at the Heart Rhythm Society's annual meeting in New Orleans.
Millions of Americans of all ages experience abnormal heart rhythms. But not all arrhythmias are alike: in some cases, irregular heartbeat is symptomatic of underlying heart disease, meaning that episodes can raise risk for fatal cardiac arrest.
The Yale authors reviewed data collected during an earlier, four-year-old study that tracked 24 cardiac patients either at high risk for heart beat irregularities or with a history of arrhythmia.
All the patients had been previously fitted with implantable defibrillators -- devices that help to control heartbeat pacing and prevent cardiac arrest by automatically delivering controlled electric shocks to the heart when heartbeat disruptions occur.
The patients were all asked to note in a diary their emotional state of mind whenever a shock occurred. A total of 107 defibrillator shocks were recorded overall. Some patients experienced few arrhythmias, while others had more frequent heartbeat irregularities.
In the original study, the researchers had concluded that patients were generally more likely to be angry just before the onset of an arrhythmia.
For this study, Stopper and his colleagues conducted a more in-depth analysis of the electrical characteristics of the arrhythmias that were recorded.
Comparing the anger-triggered arrhythmias with those not associated with anger, they found that anger-associated arrhythmias were typically instigated by the onset of at least one extra heartbeat -- an occurrence called "premature ventricular contraction." By comparison, only a little more than two-thirds of the non-anger arrhythmias were provoked by such extra heartbeat contractions.
Based on the extra contraction and anger association, the Yale team concluded that anger-related arrhythmias tend to be more "disorganized" or less stable and, therefore, inherently more dangerous.
Stopper and his team speculate that anger may provoke the release of higher levels of adrenaline -- the stress-related hormone.
While they could not establish an adrenalin-arrhythmia connection in the current study, such an association might help explain why sudden cardiac arrest is more common during times of personal stress and stresses related to larger issues, such as war and natural disaster.
"We do not have definitive evidence that adrenalin was the cause, but that's what we presume, and we'll need further research to bear that out," said Stopper.
"There's no evidence in the study that adrenalin levels are causing this, but I think that's the most likely culprit," concurred Dr. Hunter C. Champion, a cardiologist and assistant professor of medicine at Johns Hopkins School of Medicine in Baltimore.
"This research gives us further support that there is a mind-body connection," he added. "A small amount of stress is what keeps us motivated, gets us going, gives us the fight-or-flight mechanism. It's OK. It's good. However, when you have a large or sudden dose of stress, this can eventually be like a circuit breaker, overwhelming the system. And overwhelming the heart can lead to disastrous consequences."
Champion said that the findings could lead scientists in the right direction towards improving their understanding of adrenalin's affect on the heart. And he believes research may prove that a combination of stress-busting lifestyle changes, plus adrenalin-controlling medication, may help save the lives of patients prone to arrhythmias.
For more on heart arrhythmias, check out the American Heart Association.