A recent study published in the Journal of the American College of Cardiology has discovered that extreme cold and heat can significantly increase the risk of hospitalisation for individuals with heart failure. The research, presented at the 2026 European Society of Cardiology Congress, analysed nearly 482,000 heart failure hospitalisations in Sweden between 2006 and 2021. The study found that short periods of extreme cold and high temperatures have a profound impact on heart failure patients.
The researchers defined cold spells as at least two consecutive days with temperatures at or below the fifth percentile for the local area between October and March. They discovered that cold spells were associated with a higher risk of heart failure hospitalisation within two to six days of exposure. The strongest statistically significant association occurred between three and five days after exposure to cold temperatures.
In contrast, higher temperatures were linked to a more immediate increase in heart failure risk, occurring within zero to three days of exposure. However, the researchers found no statistically significant association between heat waves and heart failure hospitalisation. Heat waves were defined as two or more days with temperatures at or above the 95th percentile for the local area between April and September.
The study's lead author, Dr Wenli Ni, a postdoctoral research fellow at the Harvard T.H. Chan School of Public Health, noted that the findings addressed an important gap in understanding how temperature affects heart failure in Nordic populations. The research highlights the potential impact of temperature extremes on people living with heart failure and the need for health systems to prepare for weather-related health emergencies.
According to the researchers, the delayed increase in hospitalisation following cold exposure and the more immediate risk associated with higher temperatures point to the need for time-sensitive measures. Patients may require closer monitoring following cold-weather alerts, while heat events may demand faster responses to prevent sudden deterioration.
Dr Tiantian Li, deputy director of the National Institute of Environmental Health at the Chinese Center for Disease Control and Prevention, emphasised that cardiovascular care must increasingly take weather conditions into account. She noted that evidence linking unsuitable temperatures to cardiovascular harm is now substantial, and research should move beyond simply documenting the association to developing practical early-warning systems.
The researchers believe that the findings could help health authorities improve preparedness for environmental stressors, particularly as climate change increases exposure to extreme temperatures. The study's results may lead to the development of more effective strategies for mitigating the impact of temperature extremes on heart failure patients.
Key points
- Exposure to extreme cold and high temperatures increases hospitalisation risk among heart failure patients.
- Health systems need to prepare for weather-related health emergencies.
- Time-sensitive measures are required to mitigate the impact of temperature extremes on heart failure patients.
