Fluffy, white snow may be the stuff of holiday greeting cards but, to cardiologists, it's a heart attack waiting to happen.
Interested in ?Add as an interest to stay up to date on the latest news, video, and analysis from ABC News.
That's why they call it "heart attack snow," said Dr. Clyde Yancy, chief of cardiology at Northwestern University Feinberg School of Medicine. It's heavy and people try to clear it too quickly for their own good.
Already, the season's first big snowstorm in Buffalo, New York, has led to several deaths, including at least three people who had heart attacks while shoveling.
Blood vessels are tighter in the cold weather, making it harder for blood to pass through them. Combine that with the stress of physical activity, and it can mean disaster for some unsuspecting shovelers, Yancy said.
Yancy, a spokesman for the American Heart Association, advises shovelers not to rush, to do the work in chunks and to avoid alcoholic beverages on the job.
"It’s a misnomer that people believe having an alcoholic beverage will warm them up," he said. "It puts the heart at more risk."
According to the American Heart Association, people also shouldn't eat a big meal beforehand, and, if possible, they should use a smaller shovel to avoid lifting heavy weight.
Yancy suggested certain people skip shoveling altogether.
"If you know you already have heart disease, maybe a little bit of snow in driveway is not so bad," he said.
Shoveling may be associated with heart attacks every year, but it's not the only winter heart attack hazard, Yancy said.
"A number of things are really different in the winter season that can have direct bearing on your heart health," he said. "Winter, itself, is a risk factor."
Stress from the holidays and changes in daylight contribute to heart attacks in the winter -- even for people who travel south for the cold months, he said.
And people are most at-risk for heart attacks when they wake up in the morning because their hormone levels are different and their blood is "stickier," Yancy said.
The flu and hypothermia also can contribute to heart attacks.
"We should all realize that, over the winter season, we're just more vulnerable," Yancy said. "Take it easy."