ABSTRACT
OBJECTIVE: This retrospective study, based on the database of hospital admissions of the region Emilia-Romagna [RER], Italy, was aimed to confirm the existence of a seasonal or weekly pattern of hospital admission of acute myocardial infarction (AMI) and to verify possible differences between nonfatal or fatal cases. METHODS: The study included all cases of patients with AMI hospitalized between 1998 and 2006. Day of admission was categorized, respectively, into four 3-month intervals, into twelve 1-month intervals, and into seven 1-day intervals for statistical analysis, performed by chi(2) test goodness of fit and partial Fourier series on total cases, males, females, and nonfatal and fatal cases. RESULTS: The database included 64 191 cases of AMI (62.9% males, 12.3% fatal). Acute myocardial infarction was most frequent in winter and least in summer (P < .0001). The highest number of cases was recorded in January and the lowest in July (P < .0001). Chronobiologic analysis showed winter peaks for total cases (January, P = .035), females (December, P = .009), and fatal cases (January, P < .001). Acute myocardial infarction was most frequent on Monday and least on Sunday (P < .0001). Comparing observed vs expected events, there was a significantly higher frequency of cases on weekdays and reduced on weekends, for total (P < .0001), nonfatal (P < .0001), and fatal cases (P = .0001). CONCLUSIONS: This study confirms a significantly higher frequency of AMI admissions in winter and on a Monday. No difference in the frequency of nonfatal vs fatal events, depending of patients' admissions on weekdays or weekends, was found.
