All that pent-up rage you’ve been feeling on the job could cause damage to the heart. Holding back anger when you’re being treated unfairly at work may increase your chances of having a heart attack, according to new information from the Stress Research Institute of Stockholm University.

Information is based on a study of 2,755 men with no history of heart attack. Researchers wanted to examine how covert coping mechanisms for unfair treatment in the workplace affected heart health.

“There was a close-response relationship between covert coping and the risk of incident myocardial infarction (heart attack) or cardiac death,” authors of the study write.

Covert coping mechanisms included waiting for things to “just go away,” letting unfair actions slide and walking away from conflict. These responses were measured using questionnaires on how the participants responded to situations they believed were unfair between themselves and co-workers or employers.

Using their responses, participants were divided into three groups based on how they coped. They were classified as either being low (8-14), medium (15-18) or high (19-32).

On follow-up, 47 of the men had had a heart attack or died from ischemic heart disease. Men who had higher covert coping scores were up to three times as likely to have a heart attack when treated unfairly by a boss than those with lower scores.

“Men who frequently used covert coping had a 2.29 times higher risk than those who did not use this coping,” authors write. “In this study, covert coping is strongly related to increased risk of hard-end-point cardiovascular disease.

While stifling anger appears to be harmful, keeping a cool head is advised. Although more investigation is needed, the authors say this poses an interesting speculation on whether or not covert coping behavior intervention would change the risk of heart attack or cardiac death.

Read the study's abstract in the Journal of Epidemiology and Community Health.