"Knowing that these fatal heart attacks and other vascular events occur relatively frequently, fire departments and other workplaces need to be prepared to recognize these events and screen for those who may be at higher risk," said study author Amna Zarar, MD, a researcher at Zeenat Qureshi Stroke Institute in St. Cloud, Minn.

For the study, the researchers gathered data from the National Institute for Occupational Safety and Health that had been received by the Centers for Disease Control and Prevention from 1998 to 2012 on deaths that occurred while firefighters were on duty. The data collected rated the activities the firefighters were engaged in prior to the cardiovascular event as either "light to moderate" or "vigorous."