People with heart disease who worry a great deal may have a higher risk of strokes, heart attacks, and an early death, reports a new study. However, researchers can't yet be certain whether anxiety is the direct cause of these problems.

What do we know already?

Psychological factors seem to play a role in our heart health. For example, many studies show that people with depression are more likely to develop heart disease than those without it.

However, much less is known about what role anxiety might play. While everyone worries at times, we're talking here about what doctors call generalised anxiety disorder, which means you worry so much that it interferes with your life. About 3 in 10 people with heart disease have symptoms of this disorder. Doctors typically diagnose anxiety disorder if someone worries a lot on most days for at least six months.

To learn more about a possible link between the two conditions, researchers have now done a study of 1,015 people with heart disease, including 106 people who also had anxiety disorder. The researchers followed up with participants every year for five to six years, on average, to find out whether they had died or had any 'cardiovascular events', including strokes, transient ischemic attacks ('mini-strokes'), heart attacks, and heart failure.

What does the new study say?

People with anxiety disorder were more likely to have died or had a cardiovascular event during the study than those without the disorder. Taking into account people's ages, the yearly rate of such problems was 9.6 percent for people with anxiety disorder and 6.6 percent for those without it.

The researchers then adjusted their findings to account for several factors that might have increased people's risks of these problems, such as the severity of their heart disease, their medication use, whether they had other health problems, and whether they smoked or took regular exercise. After making these adjustments, they found that people with anxiety disorder were 74 percent more likely to have died or had a cardiovascular event.

One of the most surprising findings, say the researchers, was the lack of an obvious explanation for this increase in risk. For example, the researchers didn't find notable differences in levels of blood markers that have been tied to both anxiety and cardiovascular events. They didn't find a link between anxiety disorder and behaviour known to increase the risk of heart problems, such as smoking.

It's possible, say the researchers, that a common underlying (and unknown) factor increases people's risk of having anxiety disorder as well as serious cardiovascular events.

How reliable are the findings?

This is one of the first studies to take a detailed look at cardiovascular events in people with heart disease and generalised anxiety disorder, and it has several strengths. The researchers carefully assessed each participant at the start of the study to find out whether they had anxiety disorder. They also did tests to determine the severity of their heart disease, and interviewed participants about their health and lifestyle. All this boosts the reliability of these findings.

However, the study wasn't designed to show cause and effect, so it can't prove that people were at higher risk of these events because they had anxiety disorder. Indeed, the researchers have yet to come up with a definite theory to explain the increase in risk.

It's also worth noting that most of the study's participants were men, so these findings may not apply to women with heart disease and anxiety disorder. This is an important research gap to fill, as women are twice as likely as men to have anxiety disorder.

Where does the study come from?

The study was done by researchers in the US and the Netherlands, and was funded by several government and private research foundations in the US. It was published in the Archives of General Psychiatry, a journal owned by the American Medical Association.

What does this mean for me?

If you have generalised anxiety disorder, the constant worry can make it difficult for you to live your life normally. And if you also have heart disease, your disorder might put you at higher risk of having a heart attack, a stroke, or another cardiovascular event.

However, the news is not all bad. Knowing you may be at higher risk can help you and your doctor to be more alert to these possible problems. Also, treatments for anxiety disorder can work well. It's possible that treating the disorder may help reduce the risk of serious cardiovascular events. Future studies will need to explore this.

What should I do now?

If you have heart disease and feel worried or anxious on most days, be sure to see your doctor, as you could have generalised anxiety disorder. We don't know yet if treating this disorder will lower your risk of cardiovascular events, but it should make you feel better in other ways, and help you enjoy life more.

From:

Martens EJ, de Jonge P, Na B, et al. Scared to death? Generalized anxiety disorder and cardiovascular events in patients with stable coronary heart disease. Archives of General Psychiatry. 2010; 67: 750-758.

To learn more, see our information on anxiety and heart failure.

© BMJ Publishing Group Limited ("BMJ Group") 2010