MedPage Today -- Colder weather may add up to more myocardial infarctions, researchers have found. Over a four-year period in England and Wales, the risk of MI increased by a relative 2% (95% CI 1.1% to 2.9%) for every 1°C drop in temperature, according to Krishnan Bhaskaran, a PhD student at the London School of Hygiene & Tropical Medicine, and colleagues.