Mohammad MA, et al. - In this prospective, population-based and nationwide setting, researchers investigated whether there was a correlation between weather and day-to-day incidence of myocardial infarction (MI). Findings suggested an association of low air temperature, low atmospheric air pressure, high wind velocity, and shorter sunshine duration with the risk of MI; the strongest connection was noted for air temperature.

Methods

• In this investigation, researchers extracted daily weather data from the Swedish Meteorological and Hydrological Institute for all MIs reported to the Swedish nationwide coronary care unit registry, Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies (SWEDEHEART) during 1998 to 2013 and then merged with each MI on date of symptom onset and coronary care unit.
• Study participants were all patients admitted to any coronary care unit in Sweden because of MI.
• Out of 280,873 patients, 92,044 were diagnosed as having ST-elevation MI.
• Weather data were accessible for 274,029 patients (97.6%), which composed the final study population.
• Between February 2017 and April 2018, data were analyzed.
• The nationwide daily mean air temperature, minimum air temperature, maximum air temperature, wind velocity, sunshine duration, atmospheric air pressure, air humidity, snow precipitation, rain precipitation, and change in air temperature were analyzed exposures.
• Researchers analyzed the nationwide daily counts of MI as outcome.

Results

• The mean (SD) age was 71.7 (12) years for 274,029 participants.
• Findings revealed that incidence of MI increased with lower air temperature, lower atmospheric air pressure, higher wind velocity, and shorter sunshine duration.
• Data reported that the most pronounced association was observed for air temperature, where a 1-SD increase in air temperature (7.4°C) was related to a 2.8% reduction in risk of MI (unadjusted incidence ratio, 0.972; 95% CI, 0.967-0.977; P <.001).
• Outcomes were consistent for non–ST-elevation MI as well as ST-elevation MI and across a large range of subgroups and health care regions.