Discuss as:

Heart attacks more deadly in winter -- but it's not the cold

/

Brr! You're more likely to die of a heart-related problem in the winter, but it's not because of the cold, researchers say.

Winter can kill you. But it’s not the cold or the snow shoveling that will do you in. Whether you live in a typically hot climate like Arizona, or a chillier area like Massachusetts, you’re more likely to succumb to some form of cardiovascular disease during the winter months, researchers reported at the annual meeting of the American Heart Association Tuesday.

Compared to the summer season, people are 26 to 36 percent more likely to die in winter from a heart attack, a stroke, heart failure or some other circulatory disease, says the study’s lead author Dr. Bryan Schwartz, a cardiovascular research fellow at the Heart Institute at Good Samaritan Hospital in Los Angeles.

Schwartz and his co-author, Dr. Robert Kloner, director of research at the hospital, examined approximately 1.7 million death certificates from 2005 to 2008 from seven U.S. locations that ranged from hot to cold: Texas, Arizona’s Maricopa County, Georgia, California’s Los Angeles County, Washington, Pennsylvania and Massachusetts.

The researchers were surprised at what they found. No matter where the data were from, the pattern was the same: Many more deaths in the winter than in the summer.

Because low temperatures have often been linked with increased death rates, “we thought the winter peak would be more prominent in cold climates like Massachusetts,” says Schwartz, now a researcher at the University of New Mexico. “But the death rates were similar. That means that temperature is a small factor -- or not a factor at all.”

Then why is winter so deadly? The researchers are uncertain, but influenza and depression are possible causes. Flu season peaks in the winter, Schwartz points out, and during winter’s shorter days, people tend to feel more down and discouraged. They may exercise less and not be as careful about what they eat.

For example, “a patient who already has congestive heart failure might not be as adherent to a low-salt diet. That can be enough to promote fluid retention and worsening heart failure and eventually death.”

That makes sense to Dr. Lee Goldberg, medical director of the heart failure and cardiac transplant center at the University of Pennsylvania.

“People who are depressed are less likely to exercise and take their medications,” he says. “And they’re also more likely to cheat a bit on their diets. “

Depression doesn’t just impact lifestyle, Goldberg says. “When people are depressed there are chemical changes that can increase stress on the cardiovascular system.”

In other words, when it comes to your heart, winter is not the time to be careless.

“You need to take care of your heart 365 days a year,” Goldberg says. “You have to make time for it, regardless of what else is going on.”

More from NBCNews.com health:

Daily multivitamins won't protect your heart, study says

Think your heart is healthy? You might be wrong

Crude campaign tells men when they're too fat