Working long hours appears to increase the chances of a second heart attack. 

A study from Canada shows that for patients who return to work after a heart attack, those who work more than 55 hours per week, compared to those working an average full-time job of 35-40 hours a week, increase their odds of having a second heart attack by about twofold.

Previous studies have found an association between working long hours and increased risk of coronary heart disease and stroke. This is the first study of its kind to examine the effect of long working hours and the risk of a second cardiovascular event among patients who return to work after a first heart attack.

Almost 1,000 participants were recruited, all of which had a history of heart attack, were younger than 60 years of age, held a paying job within the year prior to their heart attack and planned to return to work.

They were monitored over the course of 6 years to assess hospital readmission rates, coronary heart disease events and lifestyle risk factors, physical or chemical exposures at work (smoking, chemicals, pollution, noise, excessive heat or cold, and physical exertion), work environment and total weekly working hours.

During the study period, 21.5 per cent of participants had a second heart attack. 

Working long hours was associated with about a twofold increase in the risk of a second heart attack. Men were more likely to be working medium/high overtime hours (10.7 per cent of men vs. 1.9 per cent of women), as well as younger workers. 

In addition, those with worse lifestyle risk factors (smoking, alcohol intake, physical inactivity), and those who worked a more stressful job were also more likely to be in the medium/high overtime category.

Researcher Dr Jian Li said the findings should ring alarm bells for OHS advocates. 

“The study provides a new piece of research evidence that work-related factors play an important role in coronary heart disease prognosis,” Dr Li said. 

“Occupational health services are urgently needed to be incorporated into secondary prevention of cardiovascular disease.”

“To reduce the risk of coronary heart disease recurrence, secondary prevention interventions aimed at reducing the number of working hours should be evaluated in future studies,” lead author Dr Xavier Trudel said. 

“Long working hours should be assessed as part of early and subsequent routine clinical follow-up to improve the prognosis of post-heart attack patients.”

The full study is accessible here.