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Lev EI, Patel RT, Maresh S, et al. Aspirin and clopidogrel drug response in patients undergoing percutaneous coronary intervention: The role of dual drug resistance. J Am Coll Cardiol. 2006; 47:27-33.


Patients who are resistant to the antiplatelet activity of aspirin are often resistant to clopidogrel (Plavix) as well. These patients may be at an increased risk for thrombotic complications after undergoing percutaneous coronary interventions (PCI). Resistance to the antiplatelet effects of aspirin is associated with adverse clinical outcomes. It has been suggested that aspirin-resistant patients be treated with an alternative antiplatelet drug, namely clopidogrel. However, there has been limited data regarding simultaneous resistance to both drugs. This research team prospectively evaluated drug resistance in 150 patients undergoing elective PCI. Laboratory tests showed that 19 (12.7%) were resistant to aspirin and 36 (24%) were resistant to clopidogrel. Nine patients were resistant to both drugs. Dual drug-resistant patients were significantly more likely to be women (67.7% vs. 26.9%, P = 0.02) and to have a higher BMI (33.8 vs. 29.7 kg/m2, P = 0.05). The authors suggest that the most likely mechanism for dual drug resistance is a global increase in platelet reactivity. They therefore suggest that other platelet inhibitors acting on additional targets (other than cyclooxygenase-1 and P2Y12) should be developed and investigated.