Effect of Temperature Variation on the Incidence of Acute Myocardial Infarction.

BACKGROUND:Harsh temperature exposure has been associated with a high risk of cardiovascular events. We sought to investigate the influence of temperature change on long-term incidence of acute myocardial infarction (AMI) in Korean patients. METHODS:From the National Health Insurance Service (NHIS) customized health information database (from 2005 to 2014), data from a total of 192,567 AMI patients was assessed according to the International Classification of Disease 10th edition code and matched with temperature reports obtained from the Korea Meteorological Administration database. We analyzed data for a 10-year period on a monthly and seasonal basis. RESULTS:The incidence rate per 100,000 year of AMI exhibited a downward trend from 69.1 to 56.1 over the period 2005 to 2014 (P < 0.005), and the seasonal AMI incidence rate per 100,000 year was highest in spring (63.1), and winter (61.3) followed by autumn (59.5) and summer (57.1). On a monthly basis, the AMI incidence rate per 100,000 year was highest during March (64.4) and December (63.9). The highest incidence of AMI occurred during temperature differences of 8-10° in each season. Moreover, AMI incidence tended to increase as the mean temperature decreased (r = -0.233, P = 0.001), and when the mean daily temperature difference increased (r = 0.353, P < 0.001). CONCLUSION:The AMI incidence rate per 100,000 year has a decreasing trend over the 10-year period, derived from the Korean NHIS database. Modest daily temperature differences (8-10°) and the spring season are related to higher AMI incidence, indicating that daily temperature variation is more important than the mean daily temperature.