IVUS results
IVUS follow-up was performed at a mean of 9.4 months after stenting (range, 5 to 19 months). No stent edge dissection was noted at post-stenting. Post-stenting peri-stent reference segment minimum lumen sites were 3.1 ± 2.1 mm from their respective proximal stent edges and 2.9 ± 1.9 mm from their respective distal stent edges. Overall, within these sites, P&M area increased (proximal edge, +0.5 ± 0.3 mm2, p < 0.001; distal edge, +0.6 ± 0.4 mm2, p < 0.001), and lumen area (proximal edge, -1.1 ± 0.5 mm2, p < 0.001; distal edge, -1.0 ± 0.4 mm2, p < 0.001) and EEM area (proximal edge, -0.6 ± 0.3 mm2, p < 0.001; distal edge, -0.4 ± 0.3 mm2, p = 0.001) decreased from post-stenting to follow-up.
Using volumetric analysis, overall, mean P&M area increased (Δ = +0.5 ± 0.5 mm2, p < 0.001 at the proximal edge and Δ = +0.6 ± 0.4 mm2, p < 0.001 at the distal edge), and mean EEM (Δ = -0.4 ± 0.3 mm2, p < 0.001 at the proximal edge and Δ = -0.3 ± 0.3 mm2, p < 0.001 at the distal edge) and mean lumen area (Δ = -0.9 ± 0.5 mm2, p < 0.001 at the proximal edge and Δ = -0.9 ± 0.4 mm2, p < 0.001 at the distal edge) decreased from post-stenting to follow-up.
For the proximal edge, mean P&M area significantly increased, and mean lumen area and mean EEM area significantly decreased at follow-up in both the simvastatin and non-statin groups. However, no significant differences were observed in changes in mean P&M (simvastatin, +0.3 ± 0.2 mm
2 vs. non-statin, +0.7 ± 0.4 mm
2;
p = 0.10), mean EEM (simvastatin, -0.4 ± 0.4 mm
2 vs. non-statin, -0.4 ± 0.3 mm
2;
p = 1.0), and mean lumen (simvastatin, -0.7 ± 0.4 mm
2 vs. non-statin, -1.1 ± 0.6 mm
2;
p = 0.11) areas from post-stenting to follow-up between the simvastatin and non-statin groups at the proximal edge. For the distal edge, mean P&M area significantly increased, and mean lumen area and mean EEM area significantly decreased at follow-up in both the simvastatin and non-statin groups. However, no significant differences were observed in changes in mean P&M (simvastatin, +0.4 ± 0.2 mm
2 vs. non-statin, +0.7 ± 0.3 mm
2;
p = 0.18), mean EEM (simvastatin, -0.3 ± 0.3 mm
2 vs. non-statin, -0.3 ± 0.2 mm
2;
p = 1.0), and mean lumen (simvastatin, -0.7 ± 0.4 mm
2 vs. non-statin, -1.0 ± 0.6 mm
2;
p = 0.19) areas from post-stenting to follow-up between the simvastatin and non-simvastatin groups at the distal edge (
Table 4,
Fig. 1).
Although lumen loss within the first 3 mm from each stent edge was primarily due to an increase in P&M area rather than a change in EEM area, and lumen loss beyond 3 mm from each stent edge was due to a combination of increased P&M area and decreased EEM area, no significant differences were observed in changes in P&M, EEM, and lumen area at every 1-mm subsegment between the simvastatin and non-statin groups (
Table 5).
In-stent restenosis occurred in 34 patients, including 14 stent edge in-stent restenosis (6 proximal edges and 8 distal edges). More significant lumen losses accompanied by a greater increase in P&M area and a greater decrease in EEM area occurred in the in-stent restenosis group as compared to the no in-stent restenosis group from post-stenting to follow-up: 1) P&M area (in-stent restenosis group, +1.4 ± 0.9 mm2 vs. no in-stent restenosis group, +0.6 ± 0.4 mm2; p < 0.001); 2) EEM area (in-stent restenosis group, -0.9 ± 0.5 mm2 vs. no in-stent restenosis group, -0.3 ± 0.3 mm2; p = 0.001); 3) lumen area (in-stent restenosis group, -2.3 ± 1.4 mm2 vs. no in-stent restenosis group, -0.9 ± 0.5 mm2; p < 0.001) No significant differences were observed in changes in P&M, EEM, and lumen areas according to the presence/absence of the use of post-stenting adjunctive balloon angioplasty.