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Timing of aspirin administration in acute myocardial infarction
  1. Polly Terry,
  2. Mark Davies
  1. Department of Emergency Medicine, Manchester Royal Infirmary, Oxford Road, Manchester M139WL, UK

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    Report by Polly Terry, Specialist Registrar Search checked by Mark Davies, Senior Clinical Fellow

    Clinical scenario

    A 49 year old man presents to the emergency department with a three hour history of central crushing chest pain. An ECG reveals an acute inferior myocardial infarction. You know that the administration of aspirin reduces future morbidity and mortality but wonder if the administration of aspirin is as time critical as thrombolysis.

    Three part question

    In [adults with an acute myocardial infarction] does [early administration of aspirin] decrease [mortality]?

    Search strategy

    Medline 1966–09/00 using the OVID interface. [(exp myocardial infarction OR myocardial OR heart AND (exp aspirin OR OR salicylic]AND maximally sensitive RCT filter LIMIT to human AND english.

    Search outcome

    Altogether 295 papers found of which 294 were either irrelevant or of insufficient quality. The remaining paper is shown in table 5.

    Table 5


    While this paper does not reach statistical significance it does show a trend in reduction of mortality with early aspirin administration. Taking this into account and the large standard deviations given a true difference may indeed exist. Other available data look at the combined effect of early thrombolysis and aspirin on the reduction of mortality and the data here are clear that the earlier the administration the greater the reduction in mortality and morbidity. Evidence exists to show that pharmacologically aspirin has maximal effect within one hour of oral administration, although whether this translates into the clinical setting is unclear. The availability of aspirin, its cost, ease of administration, and the minimal risks associated with a single dose make it an ideal immediate treatment to be given prehospital admission. The available data however suggest that this is not so time critical, that other factors cannot be taken into consideration, gor example, gastrointestinal upset, respiratory contraindications, etc.

    Clinical bottom line

    In an acute myocardial infarction, aspirin should be given as early as possible.

    Report by Polly Terry, Specialist Registrar Search checked by Mark Davies, Senior Clinical Fellow