According to a study set to be presented at the American College of Cardiology's 67th Annual Scientific Session, extreme swings in temperature on a day-to-day basis may lead to heart attacks.

Previous research has shown that cardiac health can be influenced by outdoor temperature as cold weather was suggested to bring the highest risk of heart attacks and strokes, killing 20 times more people than hot weather did. 

But the new study is the first one to focus on sudden temperature changes rather than the overall weather. 

"Global warming is expected to cause extreme weather events, which may, in turn, result in large day-to-day fluctuations in temperature," said Hedvig Andersson, the lead author of the study who works as a cardiology researcher at the University of Michigan. "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."

As a consequence of climate change, extreme weather is known to cause intense heat waves and cold snaps. Researchers are growingly concerned as unseasonal and unpredictable weather patterns have even led to deaths

"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," Andersson added.

Andresson and his team studied data collected from more than 30,000 patients treated at 45 Michigan hospitals between 2010 and 2016. All the patients were diagnosed with ST-elevated myocardial infarction, which is the most serious form of heart attack. They went on to receive a procedure (Percutaneous Coronary Intervention) which involved the opening of clogged arteries. 

Researchers were able to retrieve the temperature fluctuation preceding each heart attack by using weather records for the hospital's ZIP code. The fluctuation was calculated as the difference between the highest and lowest temperatures of that particular day. 

Results showed that the risk of a heart attack increased by about 5 percent for every five-degree jump in temperature differential. A hot summer day, with a temperature fluctuation of 35-40 degrees Celsius, saw nearly twice as many heart attacks compared to the days without fluctuations.

Hitinder Gurm, the senior author of the study, explains that heart attack risk factors are usually geared toward individuals and eventually solved through medication and lifestyle changes. The associate chief clinical officer at Michigan Medicine believes that a similar approach is required to deal with population-level risk factors.

"Temperature fluctuations are common and [often] predictable. More research is needed to better understand the underlying mechanisms for how temperature fluctuations increase the risk of heart attacks, which would allow us to perhaps devise a successful prevention approach," Gurm said. 

He added that there is still a priority to focus on modifiable cardiovascular risk factors such as smoking, high blood pressure, and high cholesterol.

Andersson will present the study Daily Temperature Fluctuations and Myocardial Infarction: Implications of Global Warming on Cardiac Health, on March 10, 2017 in Orlando.