Extremely cold temperatures increase the risk of death among people with cardiovascular disease, according to new research.
As freezing conditions brought heavy snow to much of the UK overnight, a study in the journal Circulation warned people who suffered from conditions including an irregular heartbeat were at greater risk whenever the weather turns harsh.
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For every 1,000 cardiovascular deaths, researchers found extremely cold days accounted for an extra nine.
The trend was less pronounced on days of extreme heat, which accounted for an additional two deaths.
It comes after the UK saw temperatures north of 40C during the summer, when excess deaths among over-65s reached their highest level since 2004.
Of the types of heart disease, the greatest number of additional deaths was found for people with heart failure, with almost 13 during extremely cold days and close to three on extremely hot days.
How was the study carried out?
The peer-reviewed global study was carried out by the Multi-Country Multi-City Collaborative Research Network.
It analysed data for more than 32 million cardiovascular deaths – the leading cause of death globally – across 27 countries on five continents between 1979 and 2019.
Deaths were compared to the hottest and the coldest 2.5% of days for each city with those on the days which had “optimal temperature”, defined as the temperature associated with the lowest rates of deaths.
“One in every 100 cardiovascular deaths may be attributed to extreme temperature days, and temperature effects were more pronounced when looking at heart failure deaths,” said the study’s co-author Haitham Khraishah, of the University of Maryland.
“While we do not know the reason, this may be explained by the progressive nature of heart failure as a disease, rendering patients susceptible to temperature effects.
“This is an important finding since one out of four people with heart failure are readmitted to the hospital within 30 days of discharge, and only 20% of patients with heart failure survive 10 years after diagnosis.”
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More work is needed to develop strategies to mitigate the impact of extreme temperatures in the face of increasing climate change, the researchers conclude.
One suggestion is to introduce targeted warning systems and advice for vulnerable people.
“We need to be on top of emerging environmental exposures,” said Barrak Alahmad, of Harvard University.
“I call upon the professional cardiology organisations to commission guidelines and scientific statements on the intersection of extreme temperatures and cardiovascular health.
“In such statements, we may provide more direction to health care professionals, as well as identify clinical data gaps and future priorities for research.”
