A new study warns that people with anxiety and depression are likely to have underlying heart problems and a test in addition to the routine cardiac test would be necessary to assess the risk.

The study by researchers at Concordia University, the Université du Québec à Montréal and the Montreal Heart Institute analyzed 2,271 patients; about half of them had cardiac arrests in the past. The other half faced risk of a heart disease as they had high cholesterol levels and blood pressure.

Nearly a fifth of people with heart diseases also suffer from anxiety and depression. Most patients with anxiety disorders were younger and more likely to smoke, the study found, compared to those without anxiety disorders. Nearly 44 percent of the people who were found with anxiety disorders were also suffering from major depressive disorders.

"An ECG is usually reliable for most people, but our study found that people with a history of cardiac illness and affected by anxiety or depression may be falling under the radar," said study co-author Simon Bacon, a professor in the Concordia Department of Exercise Science and a researcher at the Montreal Heart Institute. "Although it is a more costly test, undergoing an additional nuclear scan seems to be more effective at identifying heart disease."

"When prescribing and performing cardiac tests, doctors should be aware of the psychological status of their patients, since it may affect the accuracy of ECG test alone," said senior researcher Kim Lavoie, a psychology professor at the Université du Québec à Montréal and a researcher at the Montreal Heart Institute."ECG tests are not detecting as many heart problems as nuclear tests among many of these patients, particularly those that are depressed, and physicians may be under diagnosing people at risk," said Professor Lavoie.

Some 2,271 people took part in the study and about half of participants had previously suffered from major heart attacks, bypass surgery or angioplasty. The other half were people exposed to heart disease because of high cholesterol levels, high blood pressure or other risk factors.

"Patients with higher depression scores reported higher fatigue and exertion levels – effects that may be attributed to depression," says Professor Lavoie. The researchers suggest such patients may be referred for nuclear testing.

"Our study indicates that detection of heart irregularities during ECGs may be influenced by the presence of mood or anxiety disorders," said lead investigator Roxanne Pelletier of the Université du Québec à Montréal and Montreal Heart Institute. "Greater efforts should be made to include routine mood or anxiety disorder screening as part of exercise stress-testing protocols."