By Anne Harding

NEW YORK - Anxiety increases heart patients' likelihood of suffering a heart attack, stroke, or heart failure, new research shows.

And the link between anxiety and such events can't be explained by health behaviors like smoking, severity of disease, or biological factors such as hormone levels or heart rate, Dr. Elisabeth J. Martens of Tilburg University, the Netherlands, and colleagues found.

"This was quite surprising," Martens told Reuters Health by email. "The next step will be to find out how anxiety disorder leads to poor cardiovascular outcomes."

People with generalized anxiety disorder experience chronic, exaggerated worry and tension. The condition typically is treated with medications and certain kinds of talk therapy.

Martens and her team had previously found an association between depression and risk of heart attacks, strokes and other cardiovascular events in the same group of patients. All were participating in the Heart and Soul Study, an investigation of the relationship between psychological disorders and cardiovascular events in 1,024 California heart disease patients.

Martens and her colleagues found that poor health behaviors-especially physical inactivity-largely explained why depressed patients fared worse.

Because anxiety is closely linked with depression, the researchers decided to look at whether generalized anxiety disorder affected outcomes too. Their analysis included 1,015 patients, 106 of whom had generalized anxiety disorder. All had stable cardiovascular disease, meaning that they had evidence of poor blood flow in their heart, but were not experiencing a worsening of their disease.

During six years of follow-up, 371 cardiovascular events-heart attack, stroke, heart failure, or death--occurred among the study participants. Nearly 10 percent of those with generalized anxiety disorder had a heart-related event in a given year, compared to about 7 percent for those without the disorder.

After the researchers accounted for dozens of factors that might explain why the anxious patients were at greater risk, such as depression, physical activity, whether or not they took prescribed medications, and inflammation, the relationship was still there, with anxiety disorder increasing risk by 74 percent.

In their paper in the Archives of General Psychiatry, Martens and her team propose a few possible explanations for the relationship; surges of "fight-or-flight" hormones due to anxiety could be a factor, they say, while anxious patients might also be less likely to seek out preventive care.

For now, Martens says, the presence of anxiety disorder in heart patients could be used to flag those at particularly high risk.

"Evaluation and treatment of anxiety may also be considered as part of the comprehensive management of patients with CHD," she added. "Anxiety disorder is common and treatable and could, therefore, be an important modifiable risk factor in patients with CHD."

SOURCE: Archives of General Psychiatry, July 2010