Time is Muscle: An important new medical report: July 2010.

20 Sep

Information contained in this important new medical report which was published in the British Journal of Cardiology: July 2010, could help save thousands of lives and have a major impact on public health in the United Kingdom and throughout the world.

” Randomised trials have shown that the earlier aspirin is taken by patients with myocardial infarction, the greater the reduction in deaths. We suggest, therefore, that patients known to be at risk of an AMI, including older people, should be advised to carry a few tablets of soluble aspirin at all times, and chew and swallow a tablet immediately, if they experience severe chest pain.

A cross-European study estimated that the median FMC in the UK is 68 minutes, but in other European countries the median delay was around 150–200 minutes. It seems, therefore, that the opportunity is widespread for what could be termed ‘immediate’ aspirin, that is, aspirin taken while medical help is awaited.

In a series of hospital admissions Garcia-Dorado et al.16 judged that “aspirin … converts 50% of potential AMIs to unstable angina and 20% of Q-wave infarctions to non-Q-wave lesions”. On the other hand, Ridker et al. failed to confirm this in the US Physicians study, but conceded that “aspirin therapy may result in a shift of fatal events to severe non-fatal events, severe events to mild events and mild events to no events”.

Blood from cigarette smokers has been shown to generate in vitro thrombi that are twice the volume of those in blood from non-smokers, while the ingestion of aspirin by smokers reduced the subsequent thrombus volume to a substantially greater degree (by 62%) compared with the reduction (38%) caused in non-smokers.30 Clearly, the earlier aspirin is taken during thrombosis, and particularly by smokers, the more important these non-platelet effects are likely to be.

The absorption of aspirin has been studied extensively. The drug in soluble and dispersible tablets is absorbed much more rapidly than from the standard tablet. Muir et al. reported that five minutes after ingestion of a soluble form, the levels of aspirin in the plasma were about 15 times the level after ingestion of the same dose in a plain tablet. Feldman found a 50% inhibition of thromboxane A2 within five minutes after a 325 mg tablet is chewed and swallowed.

Self-administration of aspirin by a subject at the time of calling an ambulance would, however, be appropriate whatever the subsequent interventions.

The administration of aspirin as early as possible during the process of thrombosis and infarction, and, hence, the effectiveness of the drug would be enhanced if patients judged to be at risk carried a few ‘adult’ (300 mg) tablets of aspirin at all times, and were instructed to chew and swallow a tablet immediately they experience symptoms suggestive of infarction. Patients to whom this is recommended should include all those known to be at increased vascular risk, and this should include older persons – perhaps those over the age of about 45 or 50 years.

The peak incidence of AMI is in the early morning and patients may be more hesitant about calling for help in those early hours. Platelets appear to be most sensitive to aggregating agents in the early morning, and in the US Physicians Health Study it was found that the eduction in AMI by aspirin was significantly greater for the events that occurred in the early morning (59%), than for those that occurred later in the day (34%). The taking of aspirin by persons themselves could, therefore, be particularly appropriate at these times.

Around 30% of patients presenting with an AMI are known to already have coronary disease, and these are likely to be on daily low-dose spirin. Others, such as patients on a statin or an antihypertensive agent, are known to be at high risk of a thrombotic event and a high proportion of these are also likely to be on aspirin. There is evidence, however, that many of these, perhaps even around half such patients, are not actually taking the drug. In any case, the half-life of aspirin in the circulation is only 15–20 minutes, and it would seem reasonable to surmise that if a thrombus develops despite daily exposure to aspirin, some fresh sensitive platelets are likely to have entered the circulation. If this is the case, an extra dose, say 300 or 600 mg of aspirin, taken in addition to the small daily dose, could be life saving.

The risk of death attributable to aspirin in trial patients is at most 4% per year,51,52 and the risk of death from a single dose of aspirin is likely to be very considerably lower than this.

Immediate aspirin should not, therefore, be advised if symptoms suggest a stroke.

The giving of aspirin by a doctor or a paramedic immediately they have contact with a patient believed to be experiencing an acute AMI, is established practice and is recommended by all the relevant professional bodies. Self-medication in this situation has already been recommended,40,58-61 but appears never to have been actively promoted.

About 35% of all deaths are attributed to coronary heart disease each year, that is 36,000 in the UK and almost 900,000 in the USA, and younger patients among these are proportionately more likely to die before reaching hospital. The earlier aspirin is taken by these patients, the greater the proportionate survival is likely to be.

People judged to be at increased vascular risk, including older persons, should, therefore, be advised to carry a few tablets of soluble aspirin at all times, and chew and swallow a tablet immediately they experience sudden severe chest pain. Consideration should also be given to the inclusion of instruction on the risks and benefits of early aspirin to persons trained in CPR.

The Key Benefits

  • The earlier aspirin is given in coronary thrombosis, the greater the reduction in deaths
  • It is also likely that early aspirin will reduce the size and severity of a myocardial infarction and it may reduce the risk of ventricular fibrillation
  • It is suggested that patients at increased vascular risk, including older people, should carry tablets of soluble aspirin at all times, and chew and swallow a tablet immediately they experience severe chest pain “

‘Time is muscle’: aspirin taken during acute coronary thrombosis
July 2010 Volume 17, Issue 4 British Journal of Cardioligy 2010;17:185-9
Authors: Peter C Elwood, Gareth Morgan, Malcolm Woollard, Andrew D Beswick



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