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You expect to treat more patients for acute myocardial infarction (AMI) after a snowstorm-but their efforts to clear the driveway may not be why. New research suggests that it's not the snow shoveling but the snowstorm itself that brings on an attack.

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Researchers looked at hospital admissions for AMI and stroke in central Texas during a 3-year period and compared this data with weather records for the same region and time frame. They found that the number of AMIs increased within 24 hours of a rapid barometric pressure drop; the greater the pressure drop, the greater the chance of an AMI. If the pressure dropped one unit on the barometer, the risk of AMI was 10% greater in the following 24 hours. A two-unit drop equaled a 20% greater risk. The researchers say that winter is harder on the heart than other seasons because it triggers greater variations in atmospheric pressure.


Barometric pressure changes didn't influence the rate of stroke. The researchers say this finding makes sense because the coronary arteries are exposed to atmospheric pressure through breathing, but the carotid arteries are more protected.




Relation of atmospheric pressure changes and the occurrences of acute myocardial infarction and stroke, The American Journal of Cardiology, PD Houck, et al., July 1, 2005.