OBJECTIVEThe impact of late incomplete stent apposition (ISA) post sirolimus eluting stent (SES) implantation in patients with acute coronary syndrome (ACS) on long-term clinical outcomes remains controversial. The aim of the present study was to evaluate the association between late ISA and clinical outcomes in patients with ACS compared with that with stable angina (SA).

METHODSFrom February 2005 to March 2007, 54 ACS patients and 83 SA patients were enrolled in this study, late ISA was determined by means of three-dimensional volumetric intravascular ultrasound (IVUS) analyses one year after SES implantation and clinical outcomes one year post IVUS were obtained in these patients.

RESULTSIn 219 treated lesions of the 137 patients, late ISA was documented in 25 lesions in 16 patients (20 ISA in 12 ACS patients vs. 5 ISA in 4 SA patients, P<0.001). Though lumen area in reference and stented segment, neointimal hyperplasia (NIH) area and percentage of NIH in stented segment, and external elastic membrane (EEM) area in reference segment were similar between two groups, EEM area in stented segment [(15.34+/-5.44) mm2 vs. (13.83+/-4.51) mm2, P=0.026], stented/reference segment EEM area ratio (1.13+/-0.22 vs. 1.02+/-0.18, P<0.001), plaque and media area [(8.43+/-3.93) mm2 vs. (7.01+/-2.93) mm2, P=0.002] was significantly lager in ACS group than that in SA group. Multivariable logistic analysis showed that ACS (OR 6.477 with 95% CI from 2.297 to 18.263, P<0.001) and stent length>or=23 mm (OR 3.680 with 95% CI from 1.181 to 11.469, P=0.025) were main independent factors of occurrence of late ISA. Incidence of main adverse cardiac events (MACE) one year post IVUS was similar between the two groups.

CONCLUSIONCompared with patients with SA, ACS patients had larger stented segment EEM area, plaque and media area as well as increased incidence of ISA. However, the incidence of MACE was similar in ACS and SA patients one year after IVUS.