Long-Term Vascular Changes After Drug-Eluting Stent Implantation Assessed by Serial Volumetric Intravascular Ultrasound Analysis

Using serial volumetric intravascular ultrasonography, we evaluated the predictors of late intimal hyperplasia (IH) increases after drug-eluting stent implantation. All eligible patients who underwent 6-month angiography without visual restenosis were requested to undergo a 2-year follow-up examination. Complete serial (after stenting and early [6-month], and late [2-year] follow-up) angiographic and intravascular ultrasound data were available for 135 patients with 143 lesions: 99 sirolimus-eluting stents and 44 paclitaxel-eluting stents. The external elastic membrane, stent, lumen, and peri-stent plaque volumes (external elastic membrane minus stent) were normalized by stent length. The percentage of IH volume was calculated as IH volume/stent volume × 100. The early reduction in the minimum lumen area was greater than the late reduction in the minimum lumen area (−0.8 ± 0.8 vs −0.2 ± 0.5 mm2, p <0.001). A progressive increase occurred in the percentage of IH volume: 8.1 ± 7.1% from baseline to 6 months and 2.4 ± 3.9% from 6 months to 2 years (p <0.001, between the early and late increases in the percentage of IH). The use of paclitaxel-eluting stents was the only independent predictor for the percentage of IH volume at 6 months (β = 0.419, p <0.001). The use of paclitaxel-eluting stents (β = 0.365, p <0.001, 95% confidence interval 3.7 to 9.7) and the post-stenting normalized plaque and media volume (β = 0.195, p = 0.020, 95% confidence interval 0.1 to 1.6) were the only independent predictors for the percentage of IH volume at 2 years. However, when the percentage of IH at 6 months was forced into the model, the percentage of IH at 6 months and the post-stenting normalized plaque and media volume, not paclitaxel-eluting stent use, predicted the 2-year percentage of IH. In conclusion, although IH continued to increase beyond 6 months, the growth rate of intima and luminal loss attenuated with time.