Exposure to extremely cold or hot temperatures increases the risk of death for heart disease patients, according to a study published in the journal Circulation.
The global analysis of more than 32 million deaths from cardiovascular causes over 40 years has identified a higher number of deaths on days of maximum or minimum temperatures compared to days of more moderate weather.
“This underscores the urgent need to develop measures that help our society mitigate the impact of climate change on cardiovascular disease,” says study co-author Haitham Khraishah, a cardiovascular disease specialist at the University of Maryland School of Medicine. (USA.).
Among types of cardiovascular disease, people with heart failure were the most likely to be negatively impacted by very hot and very cold days, experiencing a 12% increased risk of dying on extremely hot days compared to days optimum temperature in a specific city.
For his part, extreme cold increased the risk of death from heart failure by 37%.
The findings were based on an analysis of health data from more than 32 million cardiovascular deaths that occurred in 567 cities in 27 countries on 5 continents between 1979 and 2019. The definition of extreme weather differed from city to city.
It was defined as the top 1 percent or bottom 1 percent of the “minimum mortality temperature,” which is the temperature at which the lowest mortality rate is achieved.
For every 1,000 cardiovascular deaths, the researchers found that
Extremely hot days (above 30°) accounted for 2.2 additional deaths.
Extremely cold days (below -6°) accounted for 9.1 additional deaths.
Of the types of heart disease, the greatest number of additional deaths occurred in people with heart failure (2.6 additional deaths on days of extreme heat and 12.8 on days of extreme cold).
This study establishes an indisputable link between extreme temperatures and mortality from heart disease
Mark T. Gladwin
Dean of Harvard Medical School
“Although we do not know why the effects of temperature were more pronounced in patients with heart failure, could be due to the progressive nature of heart failure as a diseaseKhraishah says. “One in four people with heart failure are readmitted to the hospital within 30 days of discharge, and only 20% of heart failure patients survive 10 years after diagnosis.”
Climate change has been found to cause extreme weather events at both ends of the spectrum, with hotter summers and colder winters. A 2021 study published in the journal “Science” found that warming of the Arctic caused a turn of events that led to a disruption of the polar vortex that caused periods of extreme cold in the northern hemisphere.
“This study establishes an indisputable link between temperature extremes and heart disease mortality from one of the largest multinational data sets ever assembled,” said Mark T. Gladwin, Dean of Harvard Medical School.