Researchers found that of people hospitalised for a heart attack, those who'd felt stressed recently were 42% more likely to die over the next two years.
It's not clear whether the stress is to blame, said lead researcher Dr Suzanne V Arnold, of St. Luke's Mid America Heart Institute in Kansas City, Missouri. But she advises patients to take some simple steps that could ease their stress, like regularly going outside for a walk.
Many studies have looked into the link between chronic stress and the risk of heart disease. In general, they've suggested that highly stressed people face a greater risk. But does chronic stress affect prognosis after a heart attack?
How the study was done
For the new study, researchers enrolled 4 200 US adults hospitalised after a heart attack. Before discharge, they answered questions about how much stress - such as job and marital stress - they'd felt in the past month.
Overall, people who reported the most stress were more likely to die over the next two years. Of more than 1 600 patients with moderate to high stress, 13% died, compared to just under 9% of less-stressed patients, the researchers reported October 3 in the Journal of the American College of Cardiology.
The numbers don't prove that stress worsens prognosis after a heart attack, Dr. Arnold said. "It's really complicated to drill down," she said.
Reasons for stress
There are a lot of reasons why people might find their lives stressful. They may be low-income, or suffer from depression, or have a generally negative disposition, for example. And those factors are tied to poorer heart health, too.
The researchers tried to control for as many confounders as possible. But they found, for example, that even in people without depression, high stress was linked to a greater risk of dying.
But it's still hard to isolate stress as the root cause of the higher death risk, Dr Arnold said.
The findings are based on 4 204 heart attack patients at 24 U.S. hospitals who answered four questions on perceived stress, for example, how often they felt "overwhelmed by difficulties piling up" and how often they felt able "to control important things."
People who scored in the top 40% were considered to have moderate to high stress levels.
The stressed patients were more likely to smoke, have depression symptoms, be obese or have high blood pressure or diabetes. But even when the researchers factored those things in, chronic stress was linked to a 42% higher risk of death over the next two years.
"I think there probably is a real effect," Dr Arnold said.
And that could mean direct or indirect effects, she noted. One direct way, in theory, could be through elevated levels of stress hormones. Indirectly, stress could "absolutely" affect people's ability to manage their health, Dr. Arnold said. They may find it harder to exercise or stick with their medications, for example.
So should doctors start measuring heart attack patients' stress levels? Dr Arnold said "it would be a stretch" to suggest that.
And so far, there's little evidence that therapies for tackling depression or chronic stress actually improve heart attack patients' long-term outlook - although they might get other benefits, like a better quality of life.
(Reuters Health, October 2012)