Extreme cold raises risk of death for people with heart problems

Scientists warn that extreme temperatures sparked by the climate crisis may be bad news for heart patients

Extremely hot and cold temperatures increase the risk of death among people with cardiovascular diseases, according to new research.

Heart problems caused by narrowed heart arteries, stroke, heart failure and arrhythmia, are linked to excess deaths from extreme temperatures, according to a study published in the American Heart Association journal Circulation.

The news comes as the UK struggles with severe cold weather, with snow, ice and fog warnings in place across the UK. Meanwhile in the US, a cold snap is affecting much of the country.

Barrak Alahmad, a researcher at Harvard University, said: "The decline in cardiovascular death rates since the 1960s is a huge public health success story as cardiologists identified and addressed individual risk factors such as tobacco, physical inactivity, Type 2 diabetes, high blood pressure and others.

"The current challenge now is the environment and what climate change might hold for us.”

Researchers explored how extreme temperatures may affect heart diseases – the leading cause of death globally. They analysed health data for more than 32 million cardiovascular deaths that occurred in 567 cities in 27 countries across five continents between 1979 and 2019.

Climate change is associated with substantial swings in extreme hot and cold temperatures, and researchers compared cardiovascular deaths on the hottest and the coldest 2.5 per cent of days for each city with cardiovascular deaths on the days that had optimal temperature (the temperature associated with the least rates of deaths) in the same city.

For every 1,000 cardiovascular deaths, the researchers found that extremely hot days accounted for 2.2 additional deaths, while extremely cold days accounted for 9.1 additional deaths.

Researchers suggest targeted warning systems and advice for vulnerable people may be needed to prevent cardiovascular deaths during temperature extremes.

“We need to be on top of emerging environmental exposures. 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,” Mr Alahmad added.

The underrepresentation of data from South Asia, the Middle East and Africa limits the ability to apply these findings to make global estimates about the impact of extreme temperatures on cardiovascular deaths.

"More work is needed to better define these relationships in a world facing climate changes across the globe in the years ahead, especially as to how those environmental changes might impact the world’s leading cause of death and disability, heart disease,” said Robert A Harrington, the former president of the American Heart Association.