Serial intravascular ultrasound analysis of stent strut distribution and fracture: An integrated analysis of the taxus IV, V, and VI trials

AIMS: Non-uniform distribution of drug-eluting stent struts may cause uneven drug deposition associated with an adverse neointimal response and clinical events. This study assesses circumferential stent strut distribution in bare-metal (BMS) and paclitaxel-eluting (Taxus) stents post implantation and at 9-month follow-up, as well as its impact on intimal hyperplasia (IH). METHODS AND RESULTS: In the current analysis, intravascular ultrasound (IVUS) substudies of the Taxus IV, V, and VI trials were combined. Among them, 242 stents (117 BMS and 125 Taxus) had paired IVUS images post procedure and at 9-month follow-up that were reassessed at 1 mm intervals. Post implantation, the maximum interstrut angle (71.5 ± 17.7° vs 70.0 ± 19.6°; P=.53) and minimum number of stent struts (7.1 ± 1.0 vs 7.2 ± 0.8; P=.32) were similar in Taxus vs BMS subgroups, respectively. At 9-month follow-up, the maximum angle increased (92.8 ± 22.1° and 81.7 ± 20.6°) and stent strut numbers decreased (6.1 ± 0.9 and 6.5 ± 1.0) for both Taxus and BMS, respectively, as compared to immediately post implantation (all P<.001). The increased stent angle was more pronounced for Taxus compared with BMS (P<.01). Non-uniform strut distribution did not affect IH pattern or clinical outcomes in either stent population. No complete stent fractures were identified. CONCLUSION: Stent strut distribution changed from implantation to follow-up with an increased interstrut angle and fewer visible stent struts. These changes were more pronounced for Taxus as compared to BMS; however, non-uniform strut distribution was unrelated to increased IH or clinical outcomes.