Cold weather may be more dangerous for the heart than extreme heat, according to new research involving a mathematician from Corvinus University of Budapest.
The large scale Hungarian study examined more than 116000 out of hospital cardiac arrest cases over five years, comparing them with daily temperature data. The research was carried out in collaboration with Semmelweis University, the Budapest University of Technology and Economics, the University of Pannonia and the National Ambulance Service. The findings were published in the January issue of Resuscitation Plus.
Researchers found that the risk of sudden cardiac arrest is lowest at around 19 C. As temperatures move higher or lower, the number of cases increases, but the effect of cold is more sustained.
Heatwaves above 27 C were linked to a short term spike in cases, typically peaking within three days. In contrast, cold periods especially when temperatures dropped below minus 9 C for several consecutive days showed a delayed but longer lasting impact. Elevated risk could persist for up to two weeks after the cold spell.
Cold days defined similarly to heatwaves, when temperatures fall below minus 10 C, carry additional risk, said Brigitta Szilagyi, Associate Professor at Corvinus University and co author of the study. She said the findings suggest that warning systems should pay greater attention to prolonged cold, not just extreme heat.
According to the researchers, the body responds differently to temperature extremes. Heat can trigger dehydration and heart rhythm disturbances. Cold increases blood pressure, constricts blood vessels and promotes blood clot formation, placing sustained strain on the cardiovascular system.
The study found no significant link between cardiac arrest and humidity, sunshine or isolated hot days. The temperature related risks were similar for men and women.
The researchers say the results have clear public health implications. While heatwaves demand rapid response, extended cold periods require longer term preparedness from healthcare services.
For individuals, experts recommend staying hydrated and limiting physical exertion during hot weather. In colder conditions, keeping warm and monitoring blood pressure may help reduce cardiovascular risk.
The study adds to growing evidence that extreme weather, particularly prolonged cold, poses a serious challenge to heart health.
Source: Corvinus University
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