Extremely hot and cold temperatures both increased the risk of death among people with cardiovascular diseases, such as ischemic heart disease (heart problems caused by narrowed heart arteries), stroke, heart failure and arrhythmia, according to new research published today in the American Heart Association’s flagship journal Circulation.
Among the cardiovascular diseases examined in this study, heart failure was linked to the highest excess deaths from extreme hot and cold temperatures.
Researchers explored how extreme temperatures may affect heart diseases – the leading cause of death globally. They analyzed health data for more than 32 million cardiovascular deaths that occurred in 567 cities in 27 countries on 5 continents between 1979 and 2019. The global data came from the Multi-Country Multi-City (MCC) Collaborative Research Network, a consortium of epidemiologists, biostatisticians and climate scientists studying the health impacts of climate and related environmental stressors on death rates.
Climate change is associated with substantial swings in extreme hot and cold temperatures, so the researchers examined both in the current study. For this analysis, researchers compared cardiovascular deaths on the hottest and the coldest 2.5% 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:
- Extreme hot days accounted for 2.2 additional deaths.
- Extreme cold days accounted for 9.1 additional deaths.
- Of the types of heart diseases, the greatest number of additional deaths was found for people with heart failure (2.6 additional deaths on extreme hot days and 12.8 on extreme cold days).
