Resistance to clopidogrel: Prevalence and associate variables

Abstract

Background: The dual antiplatelet therapy with acetylsalicylic acid (ASA) and clopidogrel is the cornerstone of treatment for patients undergoing angioplasty with coronary stent implantation. However, some of these patients, despite the use of aspirin and clopidogrel, are not effectively anti-aggregated, a phenomenon known as resistance to antiplatelet agents. Its prevalence, as well as the conditions associated with it, is unknown in our country. Objective: To determine the prevalence of clopidogrel resistance, as well as variables associated with it. Methods: Patients admitted for elective angioplasty in chronic use of ASA and clopidogrel between January 2007 and January 2010 were studied. One hour after the procedure, platelet aggregation was measured using optical aggregometry with adenosine diphosphate 5 mmoles / l as agonist. At that moment, in a cross-sectional cohort, we determined the prevalence of clopidogrel resistance, defined as the value of platelet aggregation ≥ 43% and a logistic regression model to the variables associated with it. Results: A total of 205 patients were analyzed (66.4 ± 11 years, 61.5% males). The prevalence of clopidogrel resistance was 38.5% (95% CI: 31.9 - 45.2%). Blood glucose (OR = 1.014; 95%CI: 1.004 - 1.023), previous myocardial infarction (OR = 2.320; 95%CI: 1.1103 - 4.892) and therapeutic response to ASA (OR = 1.057; 95%CI: 1.017 - 1.099) were the variables independently associated with clopidogrel resistance. Conclusion: The prevalence of clopidogrel resistance was high. Glycemia, acute myocardial infarction and response to ASA were variables associated with it. A better understanding of this phenomenon is necessary considering the new antiplatelet aggregant agents.