Abstract 4021: Clopidogrel 150 Mg/day to Overcome Low Responsiveness in Patients Undergoing Elective Percutaneous Coronary Intervention. Results from the Vasp-02 Randomized Study
We investigated whether maintenance therapy with clopidogrel 150 mg/day produces higher platelet inhibition than the standard 75 mg/day dose, and whether the higher maintenance dose increases platelet inhibition in low responders to clopidogrel 75 mg/day. Patients show interindividual variability in their platelet response to clopidogrel. Low responders could potentially obtain greater clinical benefit from higher clopidogrel doses. One hundred fifty three elective percutaneous coronary intervention (PCI) patients were randomized to clopidogrel 150 mg/day (n=58) or 75 mg/day (n=95) for four weeks, with vasodilator-stimulated phospho-protein (VASP) assay-guided switching to clopidogrel 150 mg/day after two weeks in ‘low responders’ (platelet reactivity index [PRI]≥69%). All patients received aspirin 75 mg/day. After two weeks, clopidogrel 150 mg/day produced a significantly lower PRI than clopidogrel 75 mg/day (43.9±17.3% vs. 58.6±17.7%; p<0.0001). The proportion of low responders was significantly lower in patients randomized to clopidogrel 150 mg/day than in those randomized to clopidogrel 75 mg/day (8.6% vs. 33.7%; p=0.0004). In the clopidogrel 75 mg/day group, 64.5% (20/31) of low responders became responders after switching to clopidogrel 150 mg/day for two weeks. No major bleeds occurred during the study; the incidence of minor bleeds was similar in each treatment group. In elective PCI patients, a 150 mg/day clopidogrel maintenance dose produces greater inhibition of platelet function than clopidogrel 75 mg/day. In low responders to clopidogrel 75 mg/day, switching to clopidogrel 150 mg/day overcomes low responsiveness in a majority of patients. These findings warrant further clinical evaluation.