Gender and circadian effects of myocardial infarctions.

This study determines if there are differences in circadian effects of myocardial infarctions (MIs) and MI type, non-ST elevation MI (NSTEMI) and ST elevation MI (STEMI), between females and males. A two-group, nonexperimental chart review was conducted. A total of 273 randomly selected patients with an acute MI were included. Data analysis included descriptive statistics, t test and chi square to determine differences between the groups. Of the 109 females, 26% had MI symptoms begin at night, 30% in the morning, 29% in the afternoon, and 15% in the evening (p = .067). In comparison, of the 164 males, 27% had MIs at night, 30% morning, 32% afternoon, and 11% evening (p < .001). There was no circadian difference between females and males and the time of day MI-related symptoms began (p = .887) or a MItype circadian effect (p = 0.466). The majority of patients had MIs during the daytime hours.