Evaluation of in-stent neointimal tissue components using integrated backscatter intravascular ultrasound: comparison of drug-eluting stents and bare-metal stents.

ABSTRACT

Although in-stent restenosis (ISR) occurs after drug-eluting stents (DES) implantation, neointimal tissue characteristics have not been fully investigated. We assessed neointimal tissue components using integrated backscatter intravascular ultrasound (IB-IVUS) after DES and bare-metal stents (BMS) implantation. Fifty-seven consecutive patients with 61 lesions underwent repeated percutaneous coronary intervention (PCI) for the treatment of ISR (DES 24 lesions, BMS 37 lesions). PCI was performed using plain old balloon angioplasty (POBA). Before PCI, we assessed neointimal tissue characteristics using IB-IVUS. Neointima was divided into four categories category 1 (-11 to -29 dB), category 2 (-29 to -35 dB), category 3 (-35 to -49 dB), and category 4 (-49 to -130 dB) according to IB values. We compared neointimal tissue components between DES and BMS. Thirty-three patients with 33 lesions (DES 17, BMS 16) were finally included. Neointima was predominantly composed of category 3 tissue in both groups (DES 68 ± 8%, BMS 73 ± 5%, P = 0.053). DES had a broader distribution of category 4 tissue component than BMS. After POBA, distal slow flow phenomenon occurred in 5 of DES (29%), whereas none of BMS. In DES, the optimal threshold of category 4 tissue to predict distal slow flow phenomenon after POBA was 30% (sensitivity 100%, specificity 92%). Neointima was mainly composed of category 3 tissue at ISR site, irrespective of DES or BMS. In DES, there was a subgroup with category 4 rich tissue, which caused distal slow flow phenomenon after POBA. IB-IVUS might be useful to identify vulnerable neointima in DES restenosis.