Key messages

• People with heart disease who stop smoking are likely to experience a decreased risk in future heart attacks or other events linked to the heart or blood vessels, such as stroke. 

• People with heart disease who stop smoking are unlikely to have worse quality of life.

Smoking and heart disease

Smoking increases the chances that a person will have a heart attack, however there is less information on whether stopping smoking can reduce the risk of having a second heart attack. 

Why we did this Cochrane Review

We wanted to find out whether stopping smoking after a heart attack can reduce the chances of having further heart attacks or other types of disease linked to the heart or blood vessels. If stopping smoking does prevent further illness this could motivate more people to quit smoking and encourage doctors and nurses to provide more active support to help people to stop. 

What did we do?

We searched for studies that lasted at least 6 months, and that included people diagnosed with heart disease who were smoking when the study started. Studies also had to measure whether people did or did not stop smoking and whether or not they had another event linked to their heart or blood vessels, such as another heart attack or a stroke. 

Search date: we included studies published up to 15 April 2021. 

What we found

We found 68 studies with 80,702 people. Most studies included adult men and women from the general population, however, 11 studies included only men. We looked at the combined results of 60 studies that measured events linked to heart disease and of 8 studies that measured people’s quality of life over a period of 6 months or more. 

What are the results of our review?

Compared with people who continued to smoke, people who stopped smoking were a third less likely to die from heart disease or stroke (evidence from 17,982 people in 18 studies) and a third less likely to have another heart attack or stroke (evidence from 20,290 people in 15 studies). Our confidence in these results was moderate (death from heart disease or stroke) and low (death from heart disease or stroke, another heart attack or another stroke) respectively. Our confidence in the strength of our results was reduced because of issues with how some of the studies were designed and carried out. However, when we only examined studies of a higher standard, we continued to find that people who stopped smoking were less likely to die from heart disease or stroke. This suggests that while we may be uncertain about how big the reduction in the chance of dying is, people who stop smoking are likely to reduce their chances of dying from heart disease or stroke to some degree. We found similar results for a decreased likelihood of dying from any cause, having another heart attack that does not lead to death and having a stroke that does not lead to death. 

We also found that people who stopped smoking had a suggested improvement in quality of life compared with those who continued smoking after being diagnosed with heart disease.