Depressive symptoms in heart attack patients can be reduced by exercise, according to a recent study.

An international team of researchers found that exercise and stopping smoking may improve depression after heart attack. It's important to reduce depressive symptoms and improve cardiovascular fitness because it lowers the individual's risk of having another heart attack.

"Patients who are depressed after a heart attack have a two-fold risk of having another heart attack or dying compared to those who are not depressed," researcher Dr. David Nanchen said in a statement.

For the study, researchers collected and analyzed data from more than 1,000 people who were part of the Swiss Acute Coronary Syndromes (ACS) cohort, a large prospective multicentre study of patients with ACS in Switzerland. Patients were enrolled between 2009 and 2013 and followed up for one year. Depression was assessed at enrolment and at one year.

They found that at one year, 27 percent of heart attack patients had persistent or new depression and 11 percent had improved depression. Patients with depression were less frequently married, had more diabetes, and were more frequently smokers than those without depression.

At one year, smoking cessation had the strongest association with improvement of depression with a 2.3 greater chance of improving depression in quitters compared to those who continued smoking. Depressed patients who had higher physical activity at the beginning of the study were also more prone to improve their depression.

"Heart attack patients who smoke and are depressed are much more likely to improve their depression if they kick the habit," Nanchen said. "While our observational study was unable to find an impact of exercise after heart attack on depressive symptoms, we did show that patients who were already physically active were more able to improve their depression. We believe that the benefits of exercise after heart attack would be shown in a randomized trial, but such a study is difficult to perform for ethical reasons."

"More than one-quarter of patients in our study reported symptoms of depression after their heart attack, which shows this is a big issue," Nanchen said. "Some had chronic depression which started before their heart attack while others became depressed as an acute reaction to the hospitalization and the event."

Nanchen advised heart attack patients to discuss smoking cessation with their doctor and to be physically active.

"You should do moderate to vigorous aerobic exercise for 30 minutes at least three times a week to be within recommended levels.3 Make sure you are working hard enough to break out in a sweat," he said. "This level of physical activity is good for your mental and physical health."

The findings are detailed in the European Heart Journal.