Climate change is a concern in many regions of the world where extreme hot and cold temperatures may affect people with cardiovascular diseases and increase the incidence of coronary events. The impact may be greater in areas with inequalities in the access to medical services.1

In the linked study (doi:10.1136/bmj.c3823), Bhaskaran and colleagues assessed the effect of temperature on the risk of myocardial infarction and other acute coronary syndromes2; they performed a time series analysis across 15 conurbations in England and Wales using clinically confirmed hospital admissions data. They found that each 1°C reduction in daily mean temperature was associated with a 2.0% (95% CI 1.1% to 2.9%) cumulative increase in the risk of myocardial infarction for 28 days; the highest risk was within two weeks of exposure. They found no association at higher temperatures.

The results for cold temperatures are consistent with several other studies,3 although others have found that myocardial infarction is associated with higher temperatures. The absence of an effect of …