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.

Resumen Introducción y objetivos Los episodios de calor extremo se asocian con una mayor morbimortalidad de los enfermos crónicos, pero su relación con el infarto de miocardio no está claramente establecida. El objetivo es analizar una posible relación entre la incidencia de infarto agudo de miocardio con elevación del segmento ST (IAMCEST) y la temperatura máxima, especialmente durante los periodos de alerta por ola de calor (PAOC).

Métodos La población estudiada son los casos de IAMCEST confirmado registrados en Código Infarto Madrid entre junio de 2013 y junio de 2017. Se estimaron las razones de tasa de incidencia (RTI) ajustadas por tendencia y estacionalidad y sus IC95% asociadas con los PAOC y con la temperatura máxima, utilizando modelos de regresión de series temporales.

Resultados Se incluyó a 6.465 casos de IAMCEST. En 66 días de PAOC hubo 212 casos y 1.816 casos durante los días de verano sin alerta (RTI = 1,14; IC95%, 0,96-1,35). La tasa de incidencia mínima se observó con temperatura máxima de 18 °C. Las temperaturas más cálidas no se asociaron con mayor incidencia (RTI = 1,03; IC95%, 0,76-1,41); por el contrario, hubo un incremento significativo con las temperaturas más frías (RTI = 1,25; IC95%, 1,02-1,54). No hubo modificación por sexo o edad.

Conclusiones Durante los PAOC entre junio de 2013 y junio de 2017 en la Comunidad de Madrid, no se observó un aumento de la incidencia de IAMCEST, pero sí durante periodos de bajas temperaturas. No cabe esperar un mayor uso de los recursos sanitarios para el IAMCEST en periodos de calor extremo, pero sí durante los periodos fríos.