Too much overtime increases risk of atrial fibrillation

People who work long hours are at increased risk for irregular heart rhythms, or atrial fibrillation. This is the conclusion reached by researchers at the University College London. Analysis of data from nearly 85,500 men and women found that those who work 55 hours per week or more have a 40 percent increased risk of developing atrial fibrillation in the next decade.

More strokes

According to research leader Mika Kivimaki, these findings could explain the already known increased risk of stroke in this group of people. "Atrial fibrillation not only contributes to strokes, but also plays a role in heart attacks and post-stroke dementia." The researchers analyzed data from 85,494 women and men from the United Kingdom, Denmark, Sweden, and Finland who had participated in one of eight studies in those countries.

Working hours were assessed at the beginning of the study between 1991 and 2004. They were divided into different groups. From less than 35 hours per week, 35 to 40 hours as normal standard, to more than 55 hours per week. At the beginning of the studies, none of the participants suffered from atrial fibrillation. In the following ten years, 1,061 new cases occurred. This represents an incidence rate of 12.4 per 1,000 people. However, in the 4,484 people who worked more than 55 hours, this figure was 17.6.

"The risk increased 1.4-fold, even when we adjusted for factors such as age, gender, socioeconomic status, obesity, recreational exercise, smoking and alcohol consumption," Kivimaki says. "Nine out of 10 conditions occurred in people who had no previous or concurrent cardiovascular disease. This suggests that the increased risk is likely the result of working long hours."

Further studies needed

Further studies are needed to explore the triggering mechanisms, according to the experts. According to the researcher, a 40 percent increased risk is a serious risk for people who already have a generally high risk of cardiovascular disease due to other risk factors. These include older age, male gender, diabetes, high blood pressure, high cholesterol, obesity, smoking and little exercise, or pre-existing heart disease.

"For a healthy young person with few or none of these risk factors, the overall risk of AF is low, even with long working hours," Kivimaki concludes. The research results were published in the European Heart Journal.

Text: Press release