Heart failure hospitalization risk increases after short-term exposure to cold spells, lower ambient temperatures and higher ambient temperatures, according to a study published in JACC, the flagship journal of the American College of Cardiology, and simultaneously presented at ESC Congress 2026. The increase in hospitalizations, seen in Sweden, shows how temperature extremes can contribute to sudden worsening of illness and the need for health systems to respond to and prepare for environmental stressors.
“To the best of our knowledge, no previous study has examined the short-term associations between extreme temperature events (cold spells and heat waves) or continuous non-optimal ambient temperatures and heart failure hospitalizations within a Nordic population,” said Wenli Ni, PhD, lead author of the study and a postdoctoral research fellow at the Center for Climate, Health, and the Global Environment at Harvard T.H. Chan School of Public Health. “This represents a critical knowledge gap, given that high-latitude settings such as Sweden are characterized by frequent cold exposure while simultaneously facing an emerging, unacclimatized vulnerability to heat as the global climate warms.”