Heart Health Heart Healthy Lifestyle

The Lion in Winter: Why Heart Attacks Peak During the Holidays

It is becoming as clear as ice that the winter, particularly the holiday season, is bad for your heart health. One study suggests that people are more likely to die of heart-related causes around the holidays than other time of the year. This has bolstered other research showing a spike in heart attacks and in unhealthy behavior during the winter months.

The study, published online in Circulation: Journal of the American Heart Association, looked at 53 million death records between 1973 and 2001. After excluding homicides, suicides and accidents, the researchers found that the rate of heart disease-related deaths, as well as deaths from other causes, rose sharply between December 25 and January 7. The death rate peaked on Christmas Day and New Year's Day. The researchers theorized that the risk is higher at the holidays because people commonly delay seeking treatment for symptoms during this busy time of year.

Other possible explanations for the holiday increase include emotional stress during the holidays, the tendency to eat and drink more alcohol, but exercise and take medication less.

Dr. Frederick A. Spencer, director of the coronary care unit at the University of Massachusetts Memorial Healthcare Center in Massachusetts, was the lead author of a study and found that there were 53 percent more heart attack cases in winter than the summer.

Says Spencer, "I think there is probably a mixture of factors that increase heart attack risk in winter, such as changes in physiology due to cold weather, increased infection rates, which we know may be a trigger for heart attacks, and seasonal effects on mood."

Heart attacks usually occur in people with atherosclerosis, or a build-up of plaque in their arteries. For a heart attack to occur, some sudden event must cause the plaque to crack and rupture, at which point blood platelets get sticky and form a clot in the artery. In cold weather, Spencer explains, blood platelets appear to be more active and stickier and therefore more likely to clot. Some studies have even shown that levels of cholesterol, which contributes to plaque, rise during the winter.

The heart may also have to work harder in cold weather because blood vessels constrict to help the body maintain body heat. That's one reason why people need to be cautious about exerting themselves by shoveling snow when they are not in good physical condition. Shoveling snow in during the winter mornings might be particularly risky because that is the time of day most heart attacks occur. Although the reasons for higher morning risk are not fully understood, it is believed that the higher levels of stress hormones people have in morning may be a factor.

The high rates of influenza and other respiratory disease in winter may also play a role in instigating heart attacks because infection causes inflammation. Inflammation, in turn, can make plaque less stable and contribute to heart attacks. The role of inflammation in heart attack is reflected by blood levels of C-reactive protein, a marker of inflammation that is associated with an increased risk of heart attack.

Lastly, depression is not uncommon in winter. Seasonal affective disorder, or SAD, is caused by the lack of exposure to sunlight during the winter months. Studies have indicated that people with depression are more susceptible to heart attacks, though the link between SAD and heart attack needs further study.

So does this mean you have to fear the winter? Spencer says no.

"The take home message is not to be afraid of the winter but to know that winter is a period of increase risk and to look at your own behaviors and see if there are things you can do to minimize that risk."

So during the winter, try to keep your heart healthy by keeping the following pointers in mind, especially during the holiday season: