Demanding jobs which leave workers little freedom to make decisions sharply increase the risk of a heart attack.

Workers suffering from “job strain” - lots of pressure but little freedom - have a 23 per cent increased risk, according to a Europe-wide study of almost 200,000 people from seven countries.

The findings confirm that lack of control, rather than stress itself,  is the most damaging aspect of the work environment on individual's health. High octane lifestyles are often less stressful than humdrum ones.

Stress can be positive or negative depending on whether it is driven by excitement or fear. Beginning in the 1980s, the Whitehall studies involving tens of thousands of civil servants in the UK showed that those in low status jobs who were required to follow orders of their bosses were more stressed, and died sooner, than the top executives handing out the orders.

Now a review of 13 published and unpublished studies from the last 25 years across Europe  (Belgium, Denmark, Finland, France, Netherland, Sweden and the UK)  has confirmed the earlier findings “with greater precision than has previously been possible”, the authors say in The Lancet.

The overall risk of a heart attack during the average 7.5 years for which the individuals were followed was 3.4 per cent, suggesting that job strain “would account for a notable proportion of [heart attacks] in working populations.”

However, Mika Kimivaki, lead author of the study from University College, London, said it had much less impact than the known risk factors of smoking with a risk of 36 per cent, and physical inactivity with a risk of 12 per cent.

The ill effects of job strain may be underestimated. In a comment on the findings, Bo Netterstrom from Bispebjerg Hospital in Copenhagen said: “Job strain is a measure of only part of a psychosocially damaging work environment. This implies that prevention of workplace stress could reduce incidence of coronary heart disease to a greater extent than stated in the author's interpretation of the calculated risk attributable to job strain.”

Job insecurity and emotional responses to the departure of colleagues leaving smaller staffs under greater pressure were likely to be “of major importance in the future,” he said.

“The present economic crisis will almost certainly increase this importance,” he added.

Research published in 2009 showed that people treated unfairly at work who suffered in silence had twice the risk of a heart attack or dying of heart disease compared with those who vented their anger. “Covert copers” had worse health than those who confronted their tormentors.

Professor Peter Weissberg, medical director at the British Heart Foundation (BHF), 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.”

Stress increases the blood pressure and makes the blood stickier by boosting the platelet count, so it clots faster. This is useful in battle when there is a high risk of injury but not helpful when arteries are already narrowed by fatty deposits. In these circumstances, stress may cause a blood clot to form which circulates round the body until it becomes lodged in the tiny coronary arteries that supply the heart muscle, causing a blockage and a heart attack.

Evidence suggests that patients whose blood pressure is slowest to return to normal following a period of stress and those with the highest platelet counts are most at risk of a stress-triggered heart attack.