People who become more physically active after suffering a heart attack, significantly reduce their risk of death, a new study has shown.

Swedish researchers looked at over 22,200 people who had suffered a heart attack between 2005 and 2013. They found that those who became more active after their heart attack halved their risk of death over the next four years.

"It is well known that physically active people are less likely to have a heart attack and more likely to live longer. However, we did not know the impact of exercise on people after a heart attack," explained the study's lead author, Dr Örjan Ekblom, of the Swedish School of Sport and Health Sciences, GIH, in Stockholm.

Participants were catergorised into four group - constantly inactive, reduced activity, increased activity or constantly active. They were followed up for an average of just over four years.

The study found that compared to those who were constantly inactive, those who undertook reduced activity had a 37% reduced risk of dying within four years.

Those who undertook increased activity had a 51% reduced risk of death, while those who were constantly active had a 59% reduced risk.

"Our study shows that patients can reduce their risk of death by becoming physically active after a heart attack. Patients who reported being physically active six to 10 weeks after the heart attack, but became inactive afterwards, seem to have a carry-over benefit. But of course, the benefits for active people are even greater if they remain physically active," Dr Ekblom said.

He insisted that these findings show that physical activity should be systematically promoted to heart attack patients.

"Exercising twice or more a week should be automatically advocated for heart attack patients in the same way that they receive advice to stop smoking, improve diet and reduce stress. Our study shows that this advice applies to all heart attack patients. For example, exercise reduced the risk of death in patients with large and small heart attacks, and for smokers and non-smokers," he noted.

The study did not look at what type of exercise the participants undertook and Dr Ekblom called for more research to determine whether there is a specific type of activity that is particularly beneficial after a heart attack.

"Should patients do resistance exercise, aerobic training, or a combination, for example? Is walking sufficient or do patients need more vigorous exercise which makes them short of breath? Answering these questions will help us to give more specific advice," he said.

Details of these findings were presented at EuroPrevent 2018, a European Society of Cardiology congress, in Slovenia.