This article was first published in The Skeptical Inquirer
A few different studies have looked at the temporal patterns of heart attacks and tried to find trends. A 2018 observational study from Sweden, called SWEDEHEART (Swedish Web System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies), examined cases of myocardial infarction between 1998 and 2013. It found that the highest number of heart attacks occurred during the Christmas and midsummer holidays.
A 1999 study examined all cases of death caused by coronary artery disease from 1985 through 1996 in Los Angeles County and found an increase in heart attacks in December and January. Similarly, a 2004 study looked at cases of death in the United States that involved heart disease between 1973 and 2001 and found spikes on Christmas Day and New Years Day.
But why? What is it specifically about the holidays that seem to increase heart attacks? As Dr. Christopher Labos wrote for the McGill Office for Science and Society, there are a few theories. Cold weather may cause vasoconstriction, which can lead to decreased blood flow. Couple this with the vigorous activity of shovelling snow, and heart attacks are certainly possible. However, this theory doesn’t account for the fact that the holiday heart attack phenomenon has also been found in the southern hemisphere or the previously mentioned increase during midsummer holidays.
Another theory is that during the holidays people may delay medical care. If true, this could mean that Christmas season 2020 will see even more heart attacks than expected. Patients may be not only unwilling to interrupt their merriment to see a doctor but entirely unable to, as COVID-19 has pushed many hospitals to the brink of their capacity.
The most likely culprit seems to be our festive overindulgences in food and drink. A 2019 study found that “celebrating Christmas is associated with higher levels of total and LDL cholesterol and a higher risk of hypercholesterolemia in individuals in the general population.” As high cholesterol is a risk factor for heart disease, this may explain some of the holiday heart attacks. Throw in some emotional stress, cold weather, and physical activity, and you’ve got a recipe for heart problems.
However, as Dr. Labos writes, the real question is what we do with this info. Christmas can’t be entirely cancelled, and I highly doubt we’ll convince everyone not to overindulge this holiday season (I can’t even convince myself). At least this data can help us understand trends in myocardial infarctions, and maybe it will even convince some people to skip the extra serving of dessert.