There has been plenty of anecdotal evidence that snow shoveling is linked to heart attacks, but Canadian researchers confirm snow shoveling can kill. Adrian Baranchuk, a professor at Queen's School of Medicine and a cardiologist at Kingston General Hospital, said two U.S. cardiology associations include snow-shoveling on their Web sites as a high-risk physical activity, but all the citation references indicate this warning was based on one or two incidents. "We thought that this evidence should not be enough to convince us that snow shoveling is potentially dangerous," Baranchuk said in a statement. Baranchuk and his team retrospectively reviewed Kingston General Hospital patient records from the two previous winter seasons and discovered that of the 500 patients who came to the hospital with heart problems during this period, 7 percent had started experiencing symptoms while shoveling snow. "That is a huge number," Baranchuk said in a statement. "Seven percent of anything in medicine is a significant proportion. Also, if we take into account that we may have missed some patients who did not mention that they were shoveling snow around the time that the episode occurred, that number could easily double." The team also identified three main factors that put individuals at a high risk when shoveling snow: 31 of the 35 patients were male, there was a family history of premature coronary artery disease, and about half were smokers. A history of regularly taking four or more cardiac medications was found to be preventative, the researchers added.