Comparison of late luminal loss response pattern after sirolimus-eluting stent implantation or conventional stenting

Background - We investigated the pattern of late luminal loss after sirolimus-eluting or bare stem implantation. Methods and Results - The study population comprised 238 patients treated with sirolimus-eluting stents and 526 patients treated with conventional stents. The distribution of late loss of sirolimus stents was largely skewed to the right and differed from the distribution for bare stents. When divided according to the presence of binary restenosis (diameter stenosis >50%), restenotic lesions in the bare stem group (26.0%) had a late loss of 1.40±0.64 mm and in the sirolimus group (7.9%) of 1.16±0.76 mm. Nonrestenotic lesions in the bare stent group had a late loss of 0.58±0.44 mm, whereas the late loss of nonrestenotic lesions in the sirolimus group remained close to zero (-0.05±0.33 mm). Differences between poststenting and follow-up measurements in the sirolimus group (late loss) resembled variations observed in repeated angiographic measurements, as assessed from a random sample of 30 segments measured repeatedly. After multivariate adjustment, stent type did not influence the degree of late loss in restenotic lesions. However, nonrestenotic bare stents had a significantly larger estimated luminal loss (0.58 mm; 95% CI, 0.52 to 0.65) than sirolimus-eluting stents, for which the predicted late loss was almost 0 (-0.04 mm; 95% CI, -0.10 to 0.02). Conclusions - The pattern of late loss after sirolimus-eluting stent implantation follows a peculiar behavior, different from lesions treated with conventional stents. Whether this is explained by an unusual statistical distribution or a biological all-or-none response of restenosis after sirolimus-eluting stenting remains to be investigated.