Research may explain winter spike in heart deaths
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Cold air temperature boosts inflammation in the body, a finding that may help explain why cardiovascular-related deaths increase in the winter months, researchers report.
In a study of adults with a history of heart attack, researchers observed that 5 consecutive days of colder weather lead to increased blood levels of two markers of inflammation (C-reactive protein, or CRP, and interleukin-6). Levels of the inflammatory marker fibrinogen rise after only 3 days of cold temperatures, they report.
The changes suggest one mechanism by which cold weather is associated with an increase in cardiovascular mortality, Dr. Alexandra Schneider of the Helmholtz Zentrum Muenchen at the German Research Center for Environmental Health in Neuherberg, and colleagues report.
Schneider’s team measured the three inflammatory markers in 5,813 blood samples from roughly 1,000 adults who had suffered a heart attack in the past 6 years. Centers participating in the study were located across a broad range of climate zones.
In the May issue of Epidemiology, the investigators report that a 10-degree Celsius decrease in the 5-day-average of air temperature before blood withdrawal was associated with a 4 percent increase in CRP and a 3.3 percent increase in interleukin-6. Fibrinogen increased by 1.3 percent, with a lag of 3 days.
“In susceptible patients, this might lead to an additional risk for cardiovascular events,” Schneider and colleagues say. Their finding, they add, “suggests a biologic mechanism” for the observed seasonal variation in death from heart disease and stroke in the elderly.
It’s known that cold temperatures increase blood pressure and put more strain on the heart, which may also help explain increased rates of sudden cardiac death during wintertime. Cold stress may also trigger processes that make blood thicker and increase its ability to clot, which can lead to cardiac events.
SOURCE: Epidemiology May 2008.
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