Background Incomplete stent apposition (ISA) has been demonstrated to be more common after drug-eluting stent (DES)implantation than after bare metal stent(BMS)implantation.Clinical outcomes of ISA remain controversial and the predictive accuracy of previous studies was limited by the short follow-up period of only 12-18 months.In the present study,we present the outcomes of a more than 2-year follow-up in patients with ISA after DES implantation.Methods From the clinical and core intravascular ultrasound(IVUS)database of the hospital,we jdentified 76 patients who had undergone DES implantation In de novo lesions between January 2004 and June 2005 and had received IVUS examination at a scheduled 6-month follow-up.Atotal of 13(17.1%)patients had documented ISA at the follow-up by IVUS.Clinical follow-up was available up to 41 months after DES implantation and up to 33 months after identification of ISA.Results Over a mean follow-up of(34±5)months(range 24-41 months),3 of the 13 patients(23.1%)suffered from ST elevated myocardial Infarction with one death.Angiography confirmed the very late stent thrombosis (ST) in the area with ISA.All the 3 patients were implanted with sirolimus eluting stents in left anterior descending artery(LAD)and the very late ST occurred at 29,31 and 32 months after DES implantation,and separately at 20,23 and 23 months after the identification of ISA.All of the 3 patients had antiplatelet therapy continued before suffering from ST, and had been apparently stable on antiplatelet monotherapy with aspirin for a long period following dual antiplatelet therapy with aspirin and clopidogrel for more than 12 months.Conclusion ISA of DES may be associated with a high incidence of very late stent thrombosis,even in clinically stable patients with dual antiplatelet therapy of at least 12 months after the procedure.