Drug-eluting stents (DES) have markedly decreased in-stent restenosis (IRA) compared with bare metal stents (BMS) and balloon angioplasty. Late improvement in luminal diameter has been demonstrated with the use of BMS, but sirolimus-eluting stents have failed to show long-term inhibition of neointimal hyperplasia in a porcine model. The risk of late catch-up phenomenon (later progression of neointimal hyperplasia) remains.

From January 2004 to September 2006, subjects were selected from patients who underwent follow-up coronary angiogram (CAG) 2 or more times after coronary stent implantation. Follow-up CAGs were reviewed, and stents implanted at nontarget lesions were subjected to analysis. Serial quantitative coronary analysis (QCA) was done for the measurement of reference vessel diameter (RVD), in-stent minimal luminal diameter (MLD), and stenosis diameter (SD).

Thirty patients underwent follow-up CAG 2 or more times; the number of implanted stents at a nontarget lesion was 42 (BMS 24; SES 15; paclitaxel-eluting stent [PES] 3). There were no differences in baseline characteristics between groups. The Table shows the results of serial QCA data of the 2 groups. Between first and second follow-up CAGs, MLD tended to increase (p = 0.187, ns) in the BMS group but continued to decrease in the DES group (p = 0.021). Mean duration between procedure and first follow-up CAG was 12 months for BMS patients and 7 months for DES patients. Mean duration between first and second follow-up CAG was 14 months for BMS patients and 9 months for DES patients.

Mean duration between procedure and 1st follow up CAG: BMS = 12 months, DES = 7 months
Mean duration between 1st and 2nd follow up CAG: BMS = 14 months, DES = 9 months

After BMS implantation, later neointimal thinning occurs because of decreased cellular components associated with apoptosis. This phenomenon seems not to occur after DES implantation; later luminal narrowing could be a problem after DES implantation, demonstrating the need for careful follow-up.