Setting tight work deadlines can raise the risk of suffering a heart attack six-fold, researchers believe.
A 'just-in-time' working culture can be damaging, say experts
Staff working hard to get a task completed on time were six times more likely to have an attack in the next 24 hours than co-workers, a study said.
Short bursts of high-pressure work were worse for the heart than stressful events in the preceding year, the Swedish study of 3,500 people said.
The study appears in the Journal of Epidemiology and Community Health.
Most of the people in the study were taking part in the Stockholm Heart Epidemiology Programme or SHEEP.
This tracked the number of first heart attacks that occurred in healthy people who were aged between 45 and 70 when the study started in the early 1990s.
From questionnaires asking about stress at work and home, the Karolinska Institute team found high demands, competition and conflict in the workplace were linked to heart attack risk.
Men were 80% more likely to have a heart attack if they had experienced a conflict at work within the preceding year.
The risk increased further if they felt strongly affected by it.
For women, a change in financial circumstances tripled their risk.
Women were also three times as likely, and men six times as likely to have a heart attack if they had taken on increased responsibilities at work, particularly when they viewed such duties negatively.
Of those questioned, 8% had experienced a stressful work-related event the day before they had a heart attack.
This was much higher than the proportion who had faced stressful events unrelated to work.
In particular, a high-pressure deadline increased the risk of a heart attack within the next 24 hours by a factor of six, while being put in a competitive situation at work doubled the risk.
Being praised by the boss also appeared to double the risk, but the researchers said this was probably associated with meeting a pressurised deadline.
Professor Andrew Steptoe, from the British Heart Foundation, said stressful experiences in life appeared to influence heart disease in two ways.
"First, we know that over the long-term factors like chronic work stress and living a socially isolated life increase our risk of coronary heart disease (CHD).
"Second, emotional factors may trigger heart attacks in people who already have advanced underlying CHD.
"We do not yet fully understand what tips the balance and triggers a heart attack in people with CHD.
"It has been known for several years that severe anger can act as a short-term trigger in susceptible people.
"This study shows that stressful experiences both in and outside work can have the same detrimental effect on the heart."
The BHF is investigating who might be most vulnerable to stress-triggered heart attacks, and what is happening biologically to cause them.
Brendan Barber, general secretary of the UK's Trades Union Congress, said: "This research highlights the need for all employers to take workloads and working hours seriously.
"The report shows that stress is not just an executive or senior management issue but a problem for all workers from lorry drivers, bullied into falsifying their driving hours records, to garment workers, overworked and working at speed to fulfil last minute orders.
"Britain has to move away from a 'just-in-time culture' to an organised and responsible approach to working time to protect the health and welfare of working people."