Abstract 13013: The Impact of Prolonged Clopidogrel Beyond 12 Months After Coronary Stenting in Patients with Acute Coronary Syndromes

Abstract

Introduction: Clopidogrel up to 12 months after an acute coronary syndrome (ACS) lowers the risk of major adverse coronary events. Guidelines recommend clopidogrel for 12 months after coronary intervention (PCI) with bare-metal (BMS) or drug-eluting (DES) stents. The value of prolonging clopidogrel beyond 12 months in PCI patients with ACS is unknown. Hypothesis: We hypothesize that prolonged clopidogrel differentially reduces adverse events in patients receiving DES compared with those receiving BMS for an ACS. Methods: We linked all PCIs in the national Veterans Affairs (VA) health system from 2002-2006 with the VA pharmacy database. VA and non-VA clinical outcomes were identified by ICD9 codes from the VA and CMS/Medicare databases. All patients who were event free at 12 months were followed for death, myocardial infarction (MI), and recurrent target vessel revascularization (TVR). The hazard ratio for prolonged clopidogrel use (more than 12 months) versus clopidogrel for less than or equal to 12 months was assessed for each outcome within each stent type, using Cox proportional hazards models. Multivariable models and propensity models were also used to adjust for confounding related to the propensity for prolonged clopidogrel treatment. Results: After exclusions, 28,507 patients had PCI and were event free at 12 months. Of these, 18,279 (64%) had an ACS at their index PCI including 9,336 (51%) who received a DES and 8,447 (46%) who received prolonged clopidogrel. Events occurring up to 4 years after PCI in these ACS patients included 1358 deaths, 1885 death or MIs, and 1335 TVRs. Prolonged clopidogrel was associated with lower risk of death (interaction p=0.04) and death or MI (interaction p=0.001) only in patients receiving DES (Table). Similar results were seen in multivariable and propensity models. Conclusions: Prolonging clopidogrel more than 12 months after PCI for ACS may lower the risk of death or MI in patients receiving DES but not in patients receiving BMS.