Global warming and climate change may influence more than just weather patterns—and politics. New research to be presented at the American College of Cardiology (ACC)’s 67th Annual Scientific Session suggests day-to-day swings in temperature could be associated with increasing heart attack incidences.

“Global warming is expected to cause extreme weather events, which may, in turn, result in large day-to-day fluctuations in temperature,” said lead researcher Hedvig Andersson, MD, with the University of Michigan, and colleagues in an ACC release. “Our study suggests that such fluctuations in outdoor temperature could potentially lead to an increased number of heart attacks and affect global cardiac health in the future.”

The researchers used data from more than 30,000 patients from 45 Michigan hospitals over a six-year span. All patients previously underwent percutaneous coronary intervention to open clogged arteries after being diagnosed with ST-elevated myocardial infarction.

The temperature fluctuation was calculated preceding each heart attack using weather records for a hospital’s ZIP code. Temperature fluctuation was defined as the difference between the highest and lowest temperatures of the day of the attack.

Results showed the risk of heart attack increased by approximately 5 percent for every five-degree Celsius increment in temperature differential. The researchers also reported that temperature swings of more than 25 degrees Celsius had more incidences of heart attacks than temperature differences of 10 to 25 degrees.

A sudden temperature change was more impactful on warmer days. On a summer day, nearly two times as many heart attacks were predicted on days with temperature fluctuation than on days without.

“While the body has effective systems for responding to changes in temperature, it might be that more rapid and extreme fluctuations create more stress on those systems, which could contribute to health problems,” the researchers said.

Though there is evidence that outdoor temperature affects the rate of heart attacks looking at overall daily temperatures, the researchers noted this is the first study which assesses the effect of sudden temperature changes on heart attack incidences.