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."
Prof Peter Weissberg, medical director at the British Heart Foundation, said: "We know that being under stress at work, and being unable to change the situation, could increase your risk of developing heart disease.
"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".