Air temperature may trigger heart attacks

Over 280, 000 patients were involved in a 16 years study with findings that suggest air temperature is an external trigger for heart attacks, with higher rates during the colder temperatures over the warmer ones. The findings were presented at ESC Congress. This was a nationwide observational study led by Prof David Erlinge from the Lund University and may be the largest study to research the links between weather conditions and incidences of heart attack factoring in things such as air pressure, sunshine duration, precipitation, and air temperature. 

Investigators studied specific weather conditions using meteorological data from hundreds of weather stations, and the Swedish myocardial infarction registry to compare weather conditions on days of all treated incidences. During the period 280, 873 heart attacks occurred which had 99% of meteorological data available. The rate of heart attacks was higher during the colder months, with consistent results across regions. Ona daily basis this means that there were 4 more heart attacks in Sweden when the temperature was less than 0 than when above 10 C. The rate was even higher with limited sunshine, higher wind velocities, and higher humidity.

The study analysed links between incidences and weather in subgroups that included those with hypertension, the elderly, those taking medications, those with previous heart attacks, and those with diabetes. The results were consistent in all groups with a higher rate of occurrence.

The human body responds to coldness by constricting superficial blood vessels, when that happens it decreases thermal conduction in the skin and increases arterial blood pressure. The body begins to shiver and the heart rate increases, which causes the metabolic rate to rise and increase body temperature. In healthy people the mechanism is usually tolerated, but in people with atherosclerotic plaques in their arteries it may cause a heart attack.