056 Clinical implications of high residual platelet reactivity under clopidogrel among tunisian patients with acute coronary syndrome

Unresponsiveness to clopidogrel or aspirin has been reported in patients with acute coronary syndrome (ACS). Recent findings have suggested that high postclopidogrel treatment platelet reactivity (HPR) may increase the risk of recurrent thrombotic events, especially after coronary angioplasty (PCI). We sought to investigate the effect of clopidogrel resistance assessed by the Impact-R device (Cone and platelet analyzer measuring whole blood platelet adhesion under flow conditions) on the incidence of major cardiovascular events (MACE) among tunisian ACS patients in dual antiplatelet therapy. Prospective study included 131 ACS patients almost of them who underwent PCI with stent implantation (76.3%). The mean age was 59.4 years ± 11.2 years. 77.9% were males, 37.4% patients had history of hypertension, and 54.3% patients were diabetic. Patients were receiving a loading dose of 300 or 600 mg followed by a maintenance dose of 75 mg, they were also receiving a maintenance dose of aspirin ranging from 125 mg to 250 mg. ADP-induced platelet aggregation were assessed at 48 hours using the Impact R (Diamed ® ). The degree of platelet adherence was evaluated as a percent of surface coverage (SC) and residual HPR was defined as a SC ≤2.8%. The clinical primary endpoint was the occurrence of MACE including cardiac death, MI and unstable angina. Clopidogrel resistance was detected in 21 pts (16%). After a mean follow-up 13.8 ± 6.1 months, 29 MACE were reported (22.1%) including 14 cardiac death (10.7%). According to ADP-induced platelet aggregation profile a significant a higher incidence of MACE in patients with HPR was noted (47.6% vs 17.3%, OR = 4.3; p = 0.002). A multivariate COX analysis showed that left ventricular dysfunction (HR = 6.1; 95% CI[2.6–14.4], clopidogrel resistance (HR = 3.04; 95% IC[1.3–6.4] and 2 or 3-vessel disease (HR = 2.6; 95% CI[1.3–6.4]) were independent predictors factors of MACE. Our prospective study, reinforce the importance of being able to detect clopidogrel resistance by platelet function test among patients with ACS.