Can higher temperatures lead to higher risk of heart attack?

Increasing temperatures due to climate change are associated with more frequent and intense heat waves, among other phenomena. At the same time, heat waves and warmer temperatures in general have been associated with poor health outcomes, including cardiovascular disease. In examining these health effects, studies have looked at temperature exposure periods ranging from long-term to shorter-term. This study aimed to assess the effect of hourly, aka ultra short-term, temperature on the risk of heart attack.

To investigate this relationship, the researchers analyzed hospital records from 2000 to 2015 from across New York State, using a dataset that includes ~98% of all hospital stays and visits in the state. To assign hourly temperature exposures, the authors used the temperature at the residential zip code of each patient and the time of heart attack, assumed to be two to three hours prior to admission, depending on severity of the event. Heart attacks were almost evenly divided among men and women, and the overall average age was 70 years old.

The authors found that an increase in hourly temperature corresponded to an increased risk of heart attack for the subsequent six hours. Even among low temperature values, a temperature increase corresponded to elevated risk. Furthermore, this relationship varied by sex: a temperature increase in this window was linked to higher risk of heart attack only among males. People younger than 65 years old also experienced a stronger estimated effect than those older than 65.

This study and its findings are unique in several ways. Firstly, the authors looked at hourly temperature and hourly hospital data, one of the first studies to do so (others have looked at daily hospital data, for example). Secondly, the authors used data from almost all heart attack hospitalizations across the state of New York, yielding population-wide results for a highly diverse population. The authors proposed that further research investigates temperature at the same hourly time scale in different regions and populations, and for other health outcomes.

Reference:
Rowland ST, Boehme AK, Rush J, Just AC, Kioumourtzoglou MA. Can ultra short-term changes in ambient temperature trigger myocardial infarction? Environ Int. 2020;143:105910  https://doi.org/10.1016/j.envint.2020.105910.