Abstract 4451: Impact of Low Responsiveness to Thienopyridine Antiplatelet Agents Before Elective Drug Eluting Stent Implantation on Subsequent Adverse Cardiac Events
Background: Dual antiplatelet therapy with aspirin and clopidogrel is the gold standard after drug eluting stents (DES) implantation. However, large inter-individual variability in the response to thienopyridines is known to exist. Recent data show that poor responsiveness to clopidogrel is associated with an increased risk of thrombotic events in patients treated with DES. Therefore, this study was designed to determine whether low response to thienopyridines correlates with the occurrence of major adverse cardiac events (MACE) in patients treated with DES.
Methods: The study group consisted of 230 consecutive patients (mean age 70.1 ± 10.6 yrs) who successfully underwent elective implantation of DES at our hospital from January to July 2007 (total; 304 coronary lesions). All patients received chronic dual antiplatelet agents (aspirin and ticlopidine or clopidogrel). We analyzed the platelet aggregation activity in those patients and 46 control patients undergoing coronary angiography without antiplatelet therapy. Platelet aggregation threshold index (PATI) was determined by using a whole blood analyzer, WBA-Neo system before DES implantation. The PATI was calculated as the concentration of ADP required to induce 50% aggregation. Patients with PATI < 6 μM were defined as low-responders. We evaluated 9-month MACE including target lesion revascularization (TLR), stent thrombosis, myocardial infarction, CABG surgery and cardiac death.
Results: The PATI levels were 1.49 ± 1.2 μM in control patients (n = 46) and 7.35 ± 7.7 μM in this study group (n = 230). The PATI levels were 3.06 ± 1.4 μM in low-responders (n =129) and 12.8 ± 8.9 μM in responders (n =101). The low-responders had higher proportion of hemodialysis (13% vs. 5%, p =0.04). Both groups had similar quantitative coronary angiographic characteristics before and post procedure. In-hospital MACE was not observed after initial procedure. Nine-month follow-up was available in all patients. The incidence of MACE in the low-responders was significantly higher than that in the responders (16.3% vs. 6.9%, p = 0.03), mainly due to TLR (11.6% vs. 6.9%).
Conclusion: Our results suggest that low response to thienopyridine antiplatelet agents is associated with the occurrence of MACE after DES implantation.