Late incomplete apposition after drug-eluting stent implantation: incidence and potential for adverse clinical outcomes

Aim Late-acquired incomplete stent apposition (ISA) has been documented after drug-eluting stent (DES) implantation; however, its clinical role remains controversial. We sought to investigate the incidence and long-term clinical consequences of late ISA after implantation of sirolimus- (SES) or paclitaxel-eluting stent (PES) in a non-selected population. Methods and results From our database, we analysed 195 consecutive patients who underwent DES placement (175 with SES and 20 with PES) into native artery lesions and had serial intravascular ultrasound studies (IVUS) performed at index procedure and after 6–8 months. They were clinically followed for 29 ± 15 months (median of 24.3 months, interquartile range 18.1–31.6 months). Late ISA was defined as separation of at least one stent strut from the vessel wall in a segment without a side-branch and where the immediate post-implantation IVUS revealed complete apposition of stent struts. We identified 10 patients (5.1%) with late ISA, three patients after PES, and seven patients after SES implantation. ISA was localized almost exclusively at body of the stents (nine out of 10 cases). Mean ISA volume and length were 44.5 ± 41.9 mm3 and 7.4 ± 11 mm, respectively. There was a marked increase in vessel volume from 416.0 ± 163.9 mm3 at baseline to 514.4 ± 247.9 mm3 at follow-up ( P = 0.001) with no significant change in plaque volume (232.4 ± 52.7 at baseline and 226.4 ± 22.3 mm3 at follow-up, P = 0.3) in patients who presented with late-acquired ISA. During the follow-up period, one patient with SES and one patient with PES who presented late-acquired ISA had late stent thrombosis and acute myocardial infarction. Conclusion Late-acquired ISA was observed in 5.1% of patients after DES implantation and is related to regional vessel positive remodelling. The relationship between late-acquired ISA and long-term adverse outcomes (e.g. stent thrombosis) requires further analysis.