The real cost of aspirin

Editor,—In the context of coronary heart disease the poor perception of the hidden cost of aspirin 1 partly stems from under-recognition of alternative therapeutic strategies for achieving the objective of primary or secondary prevention of myocardial infarction during long term use. A prime example is the use of warfarin, which, in patients who already have a strong indication such as atrial fibrillation, for its long term use, can serve as a satisfactory alternative therapeutic strategy. This is because, in its own right, anticoagulation to a target international normalised ratio (INR) of 1.4–2.0 can reduce the risk of myocardial infarction by 47% in high risk males aged 45–69.2 This compares favourably with the 34% reduction in myocardial infarction risk achievable with aspirin in chronic stable angina.3 For secondary prevention of myocardial infarction, prospective studies show at least comparable efficacy between warfarin (adjusted to target INR of 2.4–4.8),4 5 and aspirin,6 while, in the meta-analytic context (antedating the comparison between aspirin and trapidil),6 data from the Antiplatelet Trialists Collaboration are less favourable than data from anticoagulant trials on the basis of “numbers needed to treat”.7 8 Statins are an alternative and powerful modality both for primary and secondary prevention of myocardial infarction in patients with modest as well as a marked increase in plasma cholesterol concentrations.9 As with warfarin,2 5 6 their benefit extends to primary prevention of stroke,10 the latter objective currently not achievable with aspirin.11 In the presence of either coronary heart disease, hypertension, or diabetes, angiotensin converting enzyme blockade can reduce myocardial infarction risk by 20%, a spin off being a 23% reduction in heart failure risk.12 Secondary prevention of myocardial infarction as well as primary prevention of heart failure after myocardial infarction, comprise two end points also achievable with β-adrenergic blockade in conventional, and in low doses, respectively.13 14 This raises the possibility of a highly beneficial drug interaction between the two modalities, perhaps unlikely to be enhanced by coprescription of aspirin, given the possibility of an adverse interaction between aspirin and enalapril.15