As daily temperatures climbed above 90 degrees Fahrenheit (F) (32 degrees Celsius) across the U.S., so did the rate of out-of-hospital (OHCA) cardiac arrest admissions to hospitals' intensive care units (ICUs). However, the heat didn't appear to affect the overall outcomes of people admitted for cardiac arrest during heat waves compared with other times, according to new, independent, preliminary research to be presented at the American Heart Association's Resuscitation Science Symposium 2026.