Antiplatelets should be prescribed to reduce the risk of a cardiovascular event. This risk reduction can be classified as primary or secondary prevention depending on whether the first or subsequent event is being prevented. The evidence for the most appropriate intervention differs between these two groups.
Secondary Prevention is the reduction of risk of a subsequent cardiovascular event, for example a heart attack or stroke. NICE have recently issued a Technology Appraisal on this topic.
The guidance states the following:
- Low dose Aspirin (75mg [Dispersible]) is "standard care"
- In patients who have had an ischaemic stroke or a transient ischaemic attack, the combination of modified-release dipyridamole and aspirin (Asasantin) is recommended for two years after the most recent event
- Only in patients who are intolerant to aspirin should clopidogrel (Plavix) be used (within the product license)
Primary Prevention is the reduction of risk of a first event. The NICE Technology Appraisal detailed above does not cover this population. In this group of patients the expected risk reducing benefits must be weighed against the potential risks associated with the treatment. It is also important to pay due regard to product licenses. Neither Asasantin nor Plavix are licensed for Primary Prevention.
An article on Bandolier has provided a sensible and evidenced approach to balancing the risks and benefits. This article concludes that at a coronary risk of 1.5% per year (or 15% in 10 years, or a CVD risk of 20% in 10 years) the benefits outweigh the risks.
Patients who are at a greater than 20% risk of their first CVD event in the next 10 years should be offered antiplatelet therapy with Low Dose Aspirin (provided their blood pressure is controlled and there are no contraindication)
Action: Prescribers should use Aspirin 75mg Dispersible as first line treatment for prevention of cardiovascular events. Where compliance is to be affected by gastrointestinal symptoms an Enteric Coated formulation can be tried before the alternative strategies listed above.
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