Heat waves, ambient temperature, and risk of myocardial infarction: an ecological study in the Community of Madrid

Abstract

Introduction and objectives: Episodes of extreme heat are associated with increased morbidity and mortality in chronically-ill patients but there is a need to clearly establish the relationship between extreme heat and myocardial infarction. The aim of this study was to analyze the relationship between the incidence of ST-segment elevation myocardial infarction (STEMI) and maximum temperature, in particular during heat wave alert periods (HWAP).

Methods: The population studied consisted of confirmed STEMI cases registered in the Infarction Code of the Community of Madrid between June 2013 and June 2017. Incidence rate ratios (IRR) adjusted for trend and seasonality and 95%CI were estimated using time series regression models.

Results: A total of 6465 cases of STEMI were included; 212 cases occurred during the 66-day period of HWAP and 1816 cases during the nonalert summer period (IRR, 1.14; 95%CI, 0.96-1.35). The minimum incidence rate was observed at the maximum temperature of 18°C. Warmer temperatures were not associated with a higher incidence (IRR,1.03; 95%CI, 0.76-1.41), whereas colder temperatures were significantly associated with an increased risk (IRR, 1.25; 95%CI, 1.02-1.54). No effect modification was observed by age or sex.

Conclusions: We did not find an increased risk of STEMI during the 66 days of HWAP in the Community of Madrid between June 2013 and June 2017. However, an increased risk was found during colder temperatures. No extra health resources for STEMI management are required during periods of extreme heat, but should be considered during periods of cold weather.

Keywords: Angioplastia primaria; Cold weather; Frío; Heat wave; Infarto de miocardio; Myocardial infarction; Ola de calor; Primary angioplasty; Riesgo; Risk; Temperatura; Temperature.