Hearty work

So you have plenty of stress at work. Should you be worried about a heart attack?

A group of researchers, led by Mika Kivimäki, a professor at University College London, say you face a 23 percent increased risk of heart attack if you have a job with high demands but little control over how and when you do the work.

In a new study, Kivimäki says working in any profession can lead to strain, but the risks are more prevalent in lower skilled jobs.

"In these jobs, if you have a high work load, you don't have much control over it because of your position and how the business is run," says Kivimäki.

There is plenty of conflicting evidence on the effect of job strain on the heart. But Kivimäki claims his team's meta-analysis "is by far the largest" and most extensive, having looked at different sub-groups and including unpublished data.

He says the study strengthens findings from previous research that has correlated stress with heart disease.

The researchers analyzed more than a dozen studies, covering nearly 200,000 people for an average of 7.5 years.

Demanding jobs

All participants completed questionnaires at the start of the study to assess job demands, excessive workloads, the level of time-pressure demands and freedom to make decisions.

Then, during the study, 2,356 heart attacks or other first-time coronary heart disease incidents were recorded.

Those with highly demanding jobs but with little control over decision-making were 23 percent more likely to have a heart attack, even after taking into account potentially confounding factors such as socioeconomic status, gender and age.

Kivimäki is quick to point out, however, that the study "associates" job strain with a small but consistent increased risk of cardiovascular heart disease but that it doesn't prove that work stress directly "causes" it.

Job strain, Kivimäki argues, can lead workers to smoke more or exercise less - habits that have long been thought to heighten the risk of cardiovascular heart disease.

"It can be that lifestyle changes, such as increased smoking or eating, actually cause increased coronary heart disease risk more than the actual stress per se," Kivimäki says.

Unhealthy lifestyles

Janni and Pedro Mpaltatzis fit into both lifestyle categories.

The two brothers leave Düsseldorf everyday at 3 a.m. to work in a meat-processing plant in Dortmund - about 50 kilometers away - and they return home at 4 p.m. at the earliest.

Their routine work is stressful. To "energize" themselves, Janni eats and Pedro smokes - up to three packs a day.

"I eat to stay awake and because I have such long hours, I'm just too tired to exercise in my freetime," says Janni who is severely overweight. "I know this is unhealthy but what can I change? The company can't afford to hire more people so that we can all work less. That's impossible in today's market."

The owner of the meat factory, who built up the business from scratch and still helps out at over 65, had a heart attack a few years ago.

A matter of choice

Nearly all doctors on the front line of preventing heart disease agree that stress is an issue.

"Stress is definitely an important risk factor," says Martin Halle, a professor of cardiology and sport medicine at the Munich Technical University and a spokesman for the European Society of Cardiology.

But it shouldn't be "overestimated or underestimated" in comparison to other risk factors.

"The most important risk factor with direct effects after just six months," says Halle, "is smoking."

John Mandrola, a cardiac electrophysiologist who practices in Louisville, Kentucky, argues in a blog that the UK study underscores the importance of choice.

"We choose what to value," writes Mandrola, "we choose how to treat our body and mind."

Mandrola says doctors can educate and treat people: "But we cannot choose for people."