Serial Assessment of Coronary Artery Response to Paclitaxel-Eluting Stents Using Optical Coherence Tomography

Background-The paucity of longitudinal, serial high-resolution imaging studies has limited our understanding of in vivo arterial response to drug-eluting stents. We sought to investigate the human coronary response to paclitaxel-eluting stent implantation, using serial optical coherence tomography assessments. Methods and Results-Thirty patients with at least 2 significant coronary lesions in different vessels were treated with a paclitaxel-eluting stent. The most severe stenosis (lesion A) was treated at the initial procedure, and the second target vessel (lesion B) was stented 3 months later. Optical coherence tomography was performed at baseline, 3-, and 9-month follow-up for lesions A and baseline and 6 months for lesions B. Prespecified end points were percent of uncovered and malapposed struts over time. In lesions A, uncovered struts were 3.77 +/- 4.94% and 3.02 +/- 4.35% at 3 versus 9 months (P = NS). Malapposed struts were 3.55 +/- 5.16% at post-procedure, 1.51 +/- 3.52% at 3 months, and 0.60 +/- 1.82% at 9 months (P < 0.05, at 3 versus 9 months). Strut-level neointimal thickness was 0.19 +/- 0.09 mm and 0.20 +/- 0.11 mm (P = NS) over time. Newly acquired malapposition was detected in 10.4% and 3.3% of 2.5-mm segments at 3- and 9-month follow-up. In lesions B, uncovered struts were 2.91 +/- 5.47% at 6-months. Malapposed struts were 4.94 +/- 6.70% post-procedure and 1.01 +/- 3.11% at 6 months (P<0.01), with 0.19 +/- 0.09-mm neointimal thickness at follow-up. Conclusions-Optical coherence tomography imaging suggested the first 3 months to be the period with most biological activity after paclitaxel-eluting stent implantation, when the proliferative reaction mainly occurs and malapposition resolves. A less active, yet continuous, dynamic arterial response, with resolution and development of malapposition, occurs through 9 months post-treatment.