Clinical InvestigationSeasonal and circadian variations of acute myocardial infarction: Findings from the Get With The Guidelines–Coronary Artery Disease (GWTG-CAD) program
Section snippets
Background
Acute myocardial infarction (AMI) is one of the leading causes of mortality in United States and worldwide.1 Seasonal variation with winter preponderance of myocardial infarction incidence has been described as early as 1937.2 Since then, multiple studies have demonstrated the chronobiology of myocardial infarction in different contexts,3., 4., 5., 6. but only a few small studies have classified myocardial infarction based on ST segment elevation.7., 8., 9. Some studies report higher incidence
Methods
We used GWTG-CAD, which is a hospital based quality improvement initiative which involved about 1800 hospitals representing >75% of myocardial infarction patients in the United States.19 Hospital participation in the program is voluntary and it includes hospitals from all regions, academic and community hospitals and urban and rural hospitals. Participating hospitals collect pertinent clinical information including demographics, medical history, diagnosis, investigation results, in-hospital
Results
We included 82,971 patients enrolled in GWTG-CAD registry based on our inclusion criteria described earlier. Out of these, more hospital admissions occurred in winter (n = 21,483), while spring (n = 20,291), summer (n = 20,543) and fall (n = 20,654) had similar admission rates. Baseline characteristics of the admissions that occurred in different seasons are given in Table I. Overall the mean age of our study population was 67.5 years, 60% were male and 74.5% were white. Although many of the
Discussion
Our results demonstrated four main points. First, there is seasonal and circadian variation in myocardial infarction. This seasonal variation was prominent in NSTEMI admissions without a statistically significant difference in STEMI admissions. Second, winter predominance in acute myocardial infarction was seen mainly in warmer southern states and was not statistically significant in northern colder states. Third, hospital admissions for AMI peaked close to 11 am in the morning with a nadir
Conclusions
Seasonal variation with winter predominance was observed in AMI admissions in this large national registry. Similar effect was seen in NSTEMI admissions, but there was no statistically significant variation in STEMI admissions. Circadian variation was seen in both NSTEMI and STEMI populations with a peak at approximately 11 am and a nadir at approximately 4 am. When stratified by regions, seasonal variation was observed predominantly in warmer southern states and was not significant in colder
Source of funding
The study was supported by a grant from American Heart Association. Data collection and management were performed by Outcome, Inc. (Cambridge, MA). The analysis of registry data was performed at Duke Clinical Research Institute (Durham, NC), which also receives funding from the American Heart Association. The sponsor was not involved in the management, analysis, or interpretation of data or the preparation of the manuscript.
Disclosures
V. Nagarajan – None.
Gregg C. Fonarow – None.
Christine Ju – None.
Michael Pencina – None.
Warren K. Laskey – None.
Thomas M. Maddox – None.
Dr. Deepak L. Bhatt discloses the following relationships - Advisory Board: Cardax, Elsevier Practice Update Cardiology, Medscape Cardiology, Regado Biosciences; Board of Directors: Boston VA Research Institute, Society of Cardiovascular Patient Care; Chair: American Heart Association Quality Oversight Committee; Data Monitoring Committees: Duke Clinical
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W. Douglas Weaver, MD served as guest editor for this article.