Having a highly demanding job, but little control over it, could be a deadly combination, UK researchers say.
They analysed 13 existing European studies covering nearly 200,000 people and found "job strain" was linked to a 23% increased risk of heart attacks and deaths from coronary heart disease.
The risk to the heart was much smaller than for smoking or not exercising, the Lancet medical journal report said.
The British Heart Foundation said how people reacted to work stress was key.
Job strain is a type of stress. The research team at University College London said working in any profession could lead to strain, but it was more common in lower skilled workers.
Doctors who have a lot of decision-making in their jobs would be less likely to have job strain than someone working on a busy factory production line.Freedom
There has previously been conflicting evidence on the effect of job strain on the heart.
In this paper, the researchers analysed combined data from 13 studies.
At the beginning of each of the studies, people were asked whether they had excessive workloads or insufficient time to do their job as well as questions around how much freedom they had to make decisions.
They were then sorted into people with job strain or not and followed for an average of seven and a half years.
One of the researchers, Prof Mika Kivimaki, from University College London, said: "Our findings indicate that job strain is associated with a small but consistent increased risk of experiencing a first coronary heart disease event, such as a heart attack."
The researchers said eliminating job strain would prevent 3.4% of those cases, whereas there would be a 36% reduction if everyone stopped smoking.'Unable to change'
Prof Kivimaki said the evidence of a direct effect of job strain on the heart was mixed.
He told the BBC job strain was linked to other lifestyle choices that were bad for the heart: "We know smokers with job strain are more likely to smoke a bit more, active people with job strain are more likely to become inactive and there is a link with obesity.
"If one has high stress at work you can still reduce risk by keeping a healthy lifestyle."
"This large study confirms this, but also shows that the negative effect of workplace strain is much smaller than, for example, the damage caused by smoking or lack of exercise.
"Though stresses at work may be unavoidable, how you deal with these pressures is important, and lighting up a cigarette is bad news for your heart. Eating a balanced diet, taking regular exercise and quitting smoking will more than offset any risk associated with your job."
Dr Bo Netterstrom, from Bispebjerg Hospital in Denmark, said other stresses at work such as job insecurity "are likely to be of major importance".
He said job strain was "a measure of only part of a psychosocially damaging work environment".