Revista Colombiana de Cardiología
versão impressa ISSN 0120-5633
LUGO, José J et al. Resistance to acetylsalicylic acid and to clopidogrel: an emergent clinical entity. Rev. Col. Cardiol. [online]. 2008, vol.15, n.4, pp. 172-183. ISSN 0120-5633.
Acetylsalicylic acid is perhaps one of the most antique drugs known worldwide since the time of Hippocrates, when willow bark was used for its analgesic and antipyretic effects. Its antiplatelet properties were known for the first time in 1967 and its mechanism of action was explained in 1971. Since then it is used mostly for its antiplatelet properties than for its analgesic or antipyretic effect. Platelet activation and aggregation play an important role in arterial thrombosis pathogenesis, which leads to acute coronary syndrome and thrombotic complications during and after percutaneous coronary interventions; for this reason, acetylsalicylic acid is the most used antiplatelet agent. Clinical trials have shown its efficacy both in primary and secondary prevention of myocardial infarction, stroke and cardiovascular death. Despite its proven benefits, the relative risk of recurrent vascular events among patients taking it remains relatively high and is estimated in 8% to 18% after two years. Therapeutic resistance to acetylsalicylic acid could partially explain this risk. Even though formal diagnostic criteria and a valid measurement system are not yet established, resistance to acetylsalicylic acid may affect 5% to 45% of the population. Given the prevalence of cardiovascular disease, the potential impact of resistance to this drug is wide. Another kind of agents that act blocking platelet aggregation are the thienopyridine derivates, that include clopidogrel. Acetylsalicylic acid and clopidogrel became the election therapy in patients that will undergo coronary intervention with stent implantation. However, there is a considerable heterogeneity to the individual response of patients exposed to these drugs. Actual data show that almost 30% to 40% of patients treated with conventional doses of clopidogrel do not have an adequate antiplatelet response. Resistance to clopidogrel is a fairly used term that still needs a clear definition. Even so, it is used to reflect that clopidogrel fails in achieving its antiaggregation effect. This review discusses current evidence in relation to the variability of the antiplatelet response of these two drugs.
Palavras-chave : resistance; acetylsalicylic acid; clopidogrel; antiplatelets; platelets.