Prognosis of patients suffering an acute coronary syndrome while already under chronic clopidogrel therapy

Objective: To assess the prognosis of patients presenting with an acute coronary syndrome (ACS) despite chronic clopidogrel therapy (CCT). Background: CCT has been shown to be beneficial in decreasing the frequency of major adverse cardiovascular events (MACE) in patients after an ACS or drug-eluting stent (DES) implantation. Some patients, however, still suffer thrombotic events while on CCT. The outcome of this particular subgroup of patients is unknown. Methods: A cohort of 1,281 patients undergoing percutaneous coronary intervention (PCI) for an ACS was studied. They were divided according to their treatment prior to the ACS. The CCT group was composed of all patients who had been taking clopidogrel for ≥30 days before the onset of the ACS (n = 175) and the no CCT group of all patients not on clopidogrel before the ACS (n = 1,106). Rates of cardiovascular death and myocardial infarction at 6 months' follow-up were compared. Results: Patients in the CCT group were older (66 ± 11 vs. 63 ± 13; P < 0.001), and more often diabetic (46.8 vs. 31.9%; P < 0.01). In-hospital outcomes were similar, including the rate of death and myocardial infarction (no CCT vs. CCT group: 4.2 vs. 2.3%; P = 0.2). At 6 months, patients already taking clopidogrel before the ACS had a higher rate of MACE than patients who were not (18.3 vs. 11.8%; P = 0.02). In multivariate analysis, CCT before the ACS was associated with a hazard ratio of 1.7 for MACE. Conclusion: This study suggests that patients suffering an ACS while under on CCT have a poor long-term prognosis, which could be linked to clopidogrel low-response.