Seasonal Pattern of Acute Myocardial Infarction in the National Registry of Myocardial Infarction

Division of Cardiology, Virginia Commonwealth University-Medical College of Virginia, Richmond 23298, USA.
Journal of the American College of Cardiology (Impact Factor: 16.5). 12/1996; 28(7):1684-8. DOI: 10.1016/S0735-1097(96)00411-1
Source: PubMed


The purpose of this study was to determine whether the rate of hospital admission for acute myocardial infarction (AMI) varies seasonally in a large, prospective U.S. registry.
Identification of specific patterns in the timing of the onset of AMI is of importance because it implies that there are triggers external to the atherosclerotic plaque. Using death certificate data, most investigators have noted a seasonal pattern to the death rate from AMI. However, it is unclear whether this observation is due to variation in the prevalence of AMI or to other factors that may alter the likelihood of a fatal outcome.
We examined the seasonal mean number of cases of AMI (adjusted for the length of days in each season) that were submitted to the National Registry of Myocardial Infarction (NRMI) by 138 high volume core hospitals over a 3-year period (December 21, 1990 through December 20, 1993) during which the number of hospitals participating in the Registry was stable. Data were analyzed using general linear modeling and analysis of variance.
High volume core hospitals reported 83,541 cases of AMI to the Registry during the study period. Approximately 10% more such cases were entered into the Registry in winter or spring than in summer (p < 0.05). The same trends were seen in both northern and southern states, men and women, patients < 70 versus > or = 70 years of age and those with Q wave versus non-Q wave AMI.
We conclude that there is a seasonal pattern to the reporting rate of cases of AMI in the NRMI. This observation further supports the hypothesis that acute cardiovascular events may be triggered by events that are external to the atherosclerotic plaque.

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Available from: Neha Chandra, Sep 28, 2015
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    • "Some studies found a statistically significant relationship between low temperature and mortality from acute myocardial infarction.29 A study conduct by Larcan et al. in France compared the meteorological parameters of the day when the infarct occurred with that of the day preceding its occurrence. "
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    ABSTRACT: BACKGROUND Seasonal variation in admissions and mortality due to acute myocardial infarction has been observed in different countries. Since there are scarce reports about this variation in Iran, this study was carried out to determine the existence of seasonal rhythms in hospital admissions for acute myocardial infarction, and in mortality due to acute myocardial infarction (AMI) in elderly patients in Isfahan city. METHODS This prospective hospital-based study included a total of 3990 consecutive patients with acute myocardial infarction admitted to 13 hospitals from January 2002 to December 2007. Seasonal variations were analyzed with the Kaplan-Meier table, log rank test, and Cox regression model. RESULTS There was a statistically significant relationship between the occurrence of heart disease based on season and type of acute myocardial infarction anatomical (P < 0.001). The relationship between the occurrence of death and season and type of AMI according to International Classification of Diseases code 10 (ICD) was also observed and it was statistically significant (P = 0.026). Hazard ratio for death from acute myocardial infarction were 0.96 [Confidence interval of 95% (95% CI) = 0.78-1.18], 0.9 (95%CI = 0.73-1.11), and 1.04 (95%CI = 0.85-1.26) during spring, summer, and winter, respectively. CONCLUSION There is seasonal variation in hospital admission and mortality due to AMI; however, after adjusting in the model only gender and age were significant predictor factors.
    ARYA Atherosclerosis 01/2014; 10(1):46-54.
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    • "We estimate the effect of the ban by comparing the observed number of AMI cases post-ban with that expected in the absence of a ban, referring to the ratio as the ''ban effect'' or the ban relative risk (RR). We consider it essential to account for the tendency for the risk of AMI to vary seasonally by year (Ornato et al., 1996), by comparing numbers pre-and post-ban for whole years or the same periods in a year (e.g., June to November), or by using results which have adjusted for season or factors believed to cause seasonal variation (e.g., temperature, humidity and influenza rates). Studies taking no account of seasonal variation, e.g., comparing five months pre-ban and five months post-ban, are rejected. "
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    ABSTRACT: We update an earlier review of smoking bans and heart disease, restricting attention to admissions for acute myocardial infarction. Forty-five studies are considered. New features of our update include consideration of non-linear trends in the underlying rate, a modified trend adjustment method where there are multiple time periods post-ban, comparison of estimates based on changes in rates and numbers of cases, and comparison of effect estimates according to post-ban changes in smoking restrictiveness. Using a consistent approach to derive ban effect estimates, taking account of linear time trends and control data, the reduction in risk following a ban was estimated as 4.2% (95% confidence interval 1.8 to 6.5%). Excluding regional estimates where national estimates are available, and studies where trend adjustment was not possible, the estimate reduced to 2.6% (1.1 to 4.0%). Estimates were little affected by non-linear trend adjustment, where possible, or by basing estimates on changes in rates. Ban effect estimates tended to be greater in smaller studies, and studies with greater post-ban changes in smoking restrictiveness. Though the findings suggest a true effect of smoking bans, uncertainties remain, due to the weakness of much of the evidence, the small estimated effect, and various possibilities of bias.
    Regulatory Toxicology and Pharmacology 01/2014; · 2.03 Impact Factor
    • "An increase in mortality from acute myocardial infarction (AMI) in the winter months was first reported in the 1930s.[164] Since, these initial observations, numerous studies have reported an increased morbidity and mortality from AMI during the autumn and winter.[165–180] In contrast, a peak period of the occurrence of AMI in Hungary was found during spring.[181182] "
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    ABSTRACT: THIS PAPER REVIEW SEASONAL PATTERNS ACROSS TWELVE CARDIOVASCULAR DISEASES: Deep venous thrombosis, pulmonary embolism, aortic dissection and rupture, stroke, intracerebral hemorrhage, hypertension, heart failure, angina pectoris, myocardial infarction, sudden cardiac death, venricular arrythmia and atrial fibrillation, and discuss a possible cause of the occurrence of these diseases. There is a clear seasonal trend of cardiovascular diseases, with the highest incidence occurring during the colder winter months, which have been described in many countries. This phenomenon likely contributes to the numbers of deaths occurring in winter. The implications of this finding are important for testing the relative importance of the proposed mechanisms. Understanding the influence of season and other factors is essential when seeking to implement effective public health measures.
    North American Journal of Medical Sciences 04/2013; 5(4):266-79. DOI:10.4103/1947-2714.110430
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