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Winter storms, like those that hit the East Coast in January, are often followed by sad reports of deaths from heart attacks related to winter weather. These reports often seem to be isolated incidents, but emerging evidence reveals a clear association between winter temperatures and heart attacks, particularly severe heart attacks. Recent research demonstrated that for every 18-degree drop in outdoor temperature below 86 degrees Fahrenheit, the risk for a severe heart attack increased by 7 percent. That means the risk of a heart attack is 28 percent higher at freezing temperatures. What accounts for the increased risk with cold weather?

There are a number of factors that raise a person’s chance of having a heart attack, but many heart attacks ultimately arise from an inability to provide enough oxygen to the heart. This can cause permanent damage to the heart and, if severe enough, can lead to death. In response to cold temperatures, the heart begins to pump more blood with every heart beat, and blood vessels in the limbs narrow (constrict). These physiological responses coupled with cold weather-associated activities such as shoveling snow increase the heart’s demand for oxygen-rich blood. In healthy individuals, this demand is readily met by increasing blood flow to the heart, but this increase is often blunted in individuals with cardiovascular disease or risk factors. Men older than 55 are twice as likely as women to experience snow-related heart problems, especially if they have a family or personal history of cardiovascular disease.

How can we use this information to protect ourselves? Some practical tips:

• Understand your own cardiovascular risk and family history.
• Maintain your preventive health care throughout the year by staying physically active, eating a balanced diet and having annual check-ups with your doctor.
• Dress appropriately for work and play in the cold to limit heat loss and its stress on the heart.
• Remember that the average shovel of snow weighs at least 10 to 15 pounds. Repetitive shoveling of these loads is a dangerous level of exertion for someone with cardiovascular risk factors, so buy a smaller shovel and take regular breaks.
• Pay attention to early signs of a cardiovascular event—chest pain, dizziness, shortness of breath—and stop immediately if they occur. If symptoms persist, seek medical attention immediately.

If knowledge is power, then the research provides the power to protect us from heart attack risk in cold weather. Think this through the next time a winter storm approaches, and spread the word to help reduce snow-related heart attacks in your community.

Shawn Bender, PhD, is a research health scientist at the Harry S. Truman Memorial Veterans’ Hospital and an assistant professor at the University of Missouri.