After sifting through about 1.7 million death certificates filed between 2005 and 2008, cardiologists Bryan Schwartz of the University of New Mexico and Robert A. Kloner of the Heart Institute at the Good Samaritan Hospital in Los Angeles found a 26 to 36 percent greater death rate for heart attacks in winter than summer “despite different locations and climates,” Kloner says. The worst months are December, January, February and the beginning of March.
The doctors analyzed the cause of death for people in Texas, Arizona, Georgia, Los Angeles, Washington state, Pennsylvania and Massachusetts. Of those who died of heart disease, the winter weather pattern was clear. In Los Angeles, for example, there were about 70 deaths per day from cardiac disease, Schwartz said. “In the summer, L.A. had an average circulatory death rate of about . . . 55 deaths per day.”
The research uncovered patterns in cardiac deaths from “seven different climate patterns,” according to the study, and “death rates at all sites clustered closely together and no one site was statistically different from any other site.” An abstract of the study was published in the American Heart Association journal Circulation.
Why winter months saw a spike in cardiac deaths isn’t clear — whether it’s cooling temperatures, shorter days, or something else about that time of year. Kloner speculates that winter presents a potential confluence of harmful triggers. Even if you “adapt to where you are, the cold still bothers you and not just the temperature,” Kloner says. And “respiratory infection may be important. When there are peaks in influenza and infection, [there are peaks] in heart-related deaths.”
There also can be emotional stress in winter months as families come together for the holidays or to watch highly charged sporting events such as the Super Bowl, often with “an overindulgence in salt and alcohol,” Kloner says. On top of that, winter holidays can mean “there’s a lot of financial pressure.”
Stuart Seides, executive director of the MedStar Heart Institute at MedStar Washington Hospital Center, says the lack of light during the winter might be a factor. “The fact that the sun isn’t up until a quarter after 7 and it is pitch black outside by 5, that is different than a spring day. [In the winter,] your circadian rhythm gets messed up.” Seides had noted in the past that heart attack admissions to Washington Hospital Center dropped during summer months, which he always attributed to people going away on vacations and relaxing. “Maybe I am looking at it the wrong way,” he says. “There may not be a reduction over the summer, but maybe an increase in the winter.”