Impact of Age on Gender Differences in the Acute Myocardial Infarction Onset–Weather Association　― Oita AMI Registry ―

Background: The onset of acute myocardial infarction (AMI) is related to weather conditions, but the impact of age on gender differences in the AMI onset–weather association has not been elucidated. Methods and Results: We analyzed the Oita AMI Registry and obtained data for 403 enrolled patients. To examine the impact of age, we categorized the patients into 4 groups: young (age ≤65 years) women (n=20); young men (n=123); elderly (age >65 years) women (n=84); and elderly men (n=176). The analyzed meteorological factors were maximum and minimum temperature, intraday temperature difference, average humidity, and average atmospheric pressure. The young women group had a higher minimum temperature (17.7±5.7℃ vs. 13.8±8.2℃, P=0.04), lower intraday temperature difference (7.0±2.6℃ vs. 8.4±2.9℃, P=0.03), higher average humidity (74.5±12.1% vs. 68.1±12.0%, P=0.03), and lower average atmospheric pressure (1,009.5±5.0 hPa vs. 1,012.9±5.8 hPa, P=0.01) than the young men group on the onset day. In the elderly groups, there was no significant difference in meteorological variables except for the intraday temperature difference 2 days before AMI onset. Conclusions: AMI onset appears to be more sensitive to weather conditions (i.e., minimum temperature, average atmospheric pressure, and average humidity) in young patients than in elderly patients. In particular, young women had AMI on days with low intraday temperature difference and high humidity relative to men.