Chronic Arterial Responses to Overlapping Paclitaxel-Eluting Stents: Insights From Serial Intravascular Ultrasound Analyses in the TAXUS-V and -VI Trials

Abstract

The purpose of this study was to use intravascular ultrasound (IVUS) to investigate chronic arterial responses at the site of and adjacent to overlapping paclitaxel-eluting TAXUS stents (PES) compared with overlapping bare-metal stents (BMS). Increased paclitaxel dose in the PES-overlap region might be associated with arterial toxicity expressed as excessive expansive remodeling, incomplete stent apposition, or aneurysm formation. In the TAXUS-V and -VI trials, 51 patients with overlapping stents (27 PES and 24 BMS) were imaged with serial IVUS immediately after procedure and at 9 months. The IVUS measurements included intimal hyperplasia (IH), peri-stent plaque plus media (P&M), and external elastic membrane (EEM) areas. Vascular responses were assessed at the proximal and distal single stent strut regions and the central overlap region. Compared with BMS, all 3 PES stent regions showed: 1) significantly decreased IH (proximal: 0.97 +/- 1.06 mm(2) vs. 3.12 +/- 2.40 mm(2), overlap: 0.74 +/- 0.91 mm(2) vs. 3.23 +/- 1.75 mm(2), distal: 0.88 +/- 0.85 mm(2) vs. 2.69 +/- 1.49 mm(2), all p < 0.05); and 2) increased P&M and EEM areas (Delta P&M, proximal: 0.96 +/- 1.36 mm(2) vs. -0.02 +/- 1.48 mm(2), overlap: 1.56 +/- 1.88 mm(2) vs. 0.29 +/- 1.82 mm(2), distal: 1.03 +/- 1.81 mm(2) vs. 0.11 +/- 0.89 mm(2), all p < 0.05). The IH and changes in EEM and P&M areas were not significantly different in both the BMS and PES groups comparing the single stent strut and overlap regions. Incomplete stent apposition did not occur at the site of overlapping PES in any patient. Nine months after stent implantation, neointimal tissue growth was reduced and expansive remodeling was greater with PES compared with BMS--effects that were not exaggerated at the overlap region of PES.