Heart World Conference 2026

Abstract

The 21st century presents a twofold challenge. First, climate change is increasing the intensity, frequency, and severity of heat periods. On the other hand, the prevalence of chronic diseases, particularly cardiovascular diseases, is on the rise. The most well-known risk associated with heat exposure is heatstroke, which occurs when the body can no longer release heat into the environment and the body temperature rises too high. However, in older adults and those living with cardiac disease, the main risk is not heatstroke, but an increase in cardiac strain (i.e. heart rate), which is necessary to pump blood to the skin to dissipate heat through sweating and the dilation of skin blood vessels. This increase in heart rate occurs to increase the cardiac output to meet the needs for oxygen of the organs, dissipate heat, and maintain blood pressure. However, aging impairs thermoregulatory mechanisms, leading to a more pronounced and prolonged increase in heart rate to dissipate more heat. Also, in people with cardiac disease, the vasomotor capacity of the coronary arteries is reduced, which limits the heart rate rise and increases the risk of myocardial ischemia. Given that myocardial ischemia is the underlying condition that can lead to arrhythmias and myocardial infarction, limiting the increase in heart rate in people living with heart disease is essential.

The objectives of this presentation are: 1) to demonstrate how heat affects the cardiovascular system; 2) to explain how aging impacts thermoregulatory responses and increases the risk associated with heat exposure; 3) to explain how heat increases the risk of adverse cardiac events in people living with heart disease when exposed to heat.

To this end, various projects from the Laboratory of Integrative Human Physiology at the Montreal Heart Institute will be presented. Some have been completed and published, while others are currently underway to address these questions.