Cold Weather Triggers Risk of Acute Myocardial Infarction

The risk of Acute Myocardial Infarction (AMI) is higher in cold weather according to the latest study presented during the conference of European Society of Cardiology (ESC).

Professor Claeys said: “Air pollution and temperature changes are the most frequently reported environmental triggers for acute AMImyocardial infarction (AMI). Epidemiologic studies have focused mainly on one environmental condition, but most environmental triggers are related to each other and may attenuate or reinforce the triggering effect of a single environmental factor.”

He added: “Better knowledge of the impact of environment on AMI will help medical care providers and policy makers to optimise prevention strategies for a target risk population.”

The objective of this study was to determine the environmental factors that could significantly increase the probability of AMI. The researchers evaluated the data of primary percutaneous coronary intervention (pPCI) on weekly basis during the time span of 2006-2009 by using national nationwide PCI database.

“AMI counts were correlated with average weekly meteorological data obtained from daily measurements in 73 meteorological sites, equally distributed in Belgium. The following meteorological measures were investigated: air pollution expressed as particulate matter both less than 10µM (PM10) and less than 2.5µM (PM2.5), black smoke, temperature and relative humidity.”

 Table 1. Study parameters and results

Total population Average age Weekly mean admission rate Time series and univariate analysis
15,964 AMI patients 63 years, 24.8% female 77 + 11 patients Significant link between AMI and air pollution, inverse association between temperature and AMI

Professor Claeys said: “Additional analysis showed that the triggering effect of low temperature was also present outside the winter period. Apparently, smaller differences in temperature between indoor and outdoor can also precipitate AMI. In addition, below a minimal temperature of 10°C there is no additional effect of temperature decrease on the occurrence of AMIs.”

He added: “A potential mechanism to explain the increased risk of coronary events associated with decreasing temperature is the stimulation of cold receptors in the skin and therefore the sympathetic nervous system, leading to a rise in catecholamine levels. Moreover, increased platelet aggregation and blood viscosity during cold exposure promotes thrombosis and clot formation.”

Professor Claeys concluded: “In a global environmental model, low temperature is by far the most important environmental trigger for AMI, whereas air pollution has a negligible effect. People at risk of AMI (for example elderly patients with diabetes and hypertension) can minimise their risk by avoiding big changes in temperature. This means wearing suitable clothes when going from the warm indoors to the colder outdoors, even beyond winter time.”

Source: European Society of Cardiology 

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