Angiographic Analysis of Pattern of Late Luminal Loss in Sirolimus- and Paclitaxel-Eluting Stents

Late loss is becoming an important end point to compare drug-eluting stents; however, little is known about its pattern of distribution. We analyzed the pattern of late loss distribution in sirolimus-eluting stents (SESs) and paclitaxel-eluting stents (PESs) in a consecutive cohort of patients. From a cohort of 529 patients treated with drug-eluting stents in 1 year, we selected all patients who underwent angiographic follow-up. Three hundred fifty-nine patients with 592 de novo lesions received SESs (286 lesions) or PESs (306 lesions). Late loss and binary angiographic restenosis were analyzed. Binary restenosis occurred in 56 lesions (19.6%) treated with SESs compared with 53 (17.3%) treated with PESs (p = 0.48). The 2 late loss distributions were skewed to the right and were not normally distributed (p <0.001 for SES, p = 0.003 for PES). Late loss was significantly lower in the SES group (p = 0.03), with a median value of 0.29 mm (interquartile range −0.09 to 0.66) versus 0.41 mm (−0.02 to 0.85) in the PES group. When analyzing only restenotic lesions, late loss had a normal distribution in the SES and PES groups (p = 0.96 and 0.44, respectively) and was similar in the 2 groups (1.75 ± 0.51 vs 1.82 ± 0.62, p = 0.48). When evaluating nonrestenotic lesions, late loss was also normally distributed in the 2 groups (p = 0.75 for SES, p = 0.73 for PES) but was significantly lower (p = 0.002) after SES implantation (0.14 ± 0.39) than after PES implantation (0.27 ± 0.44). In conclusion, SESs and PESs have a bimodal pattern of late loss distribution. The observed difference in late loss between SES and PES seems to be partly explained by the decrease in late loss after SES implantation in nonrestenotic lesions (where SES approaches “zero late loss”). Thus, late loss may not be a reliable marker of the true efficacy of these devices due to its complex and nongaussian distribution.