Duration of dual antiplatelet therapy following percutaneous coronary intervention on re-hospitalization for acute coronary syndrome

Background: The optimal duration of dual antiplatelet therapy after percutaneous coronary intervention (PCI) remains uncertain. The objective of this study was to examine the association between duration of dual antiplatelet therapy and re-hospitalization for acute coronary syndrome (ACS) in ACS patients who underwent PCI. Methods: We identified 975 newly diagnosed ACS patients who underwent PCI between July, 2007 and June, 2009, at a medical center in Taiwan. Cox proportional hazard models were used to examine the association between duration of dual antiplatelet therapy (9 months, 12 months and 15 months) and risks of re-hospitalization for ACS. Results: At a mean follow-up of 2.3 years, we found that use of clopidogrel for >= 12 months was associated with a decreased risk of re-hospitalization for ACS (adjusted HR 0.59, 95% CI 0.36-0.95; p = 0.03). However, use of clopidogrel for >= 15 months was not associated with a decreased risk of re-hospitalization for ACS (adjusted HR 0.57, 95% CI 0.29-1.13; p = 0.11). Similar results were found in patients who implanted drug-eluting stents (DES), for whom at least 12 months of clopidogrel therapy is especially critical. Conclusion: The benefit of >= 12 months of clopidogrel use in reducing the risk of re-hospitalization for ACS was significant among ACS patients who underwent PCI and was especially critical for those who implanted DES.