Implicaciones de la expansión tardía de los stents autoexpandibles sobre la respuesta neointimal: estudio seriado con ecografía intravascular

34 Introduction and objectives. A unique property of self-expanding stents is the continuous force exerted against the vessel wall, which may induce additional arte- rial damage with implications on restenosis. The main purpose of this study is to evaluate the consequences of late self-expansion of coronary Wallstents. Methods. Eleven patients with Wallstents implanted in native coronary arteries, in whom baseline, post-stenting, after high pressure balloon inflation and at 6-month fo- llow-up intravascular ultrasound were performed. The stented segments were divided in 2-mm cross-sections, that were analyzed independently and carefully matched at each situation using anatomic landmarks. Multiple re- gression analysis was performed. Results. Late expansion was present in 93% of the stu- died sections (mean increase in stent area of 2.0 ± 1.9 mm 2 ) and was clearly related to stent oversizing (r = .45; P < .0001). Although late expansion was a significant positive predictor of neointimal growth (r = .63; P < .0001), it sho- wed a negative correlation with late luminal loss (r = -.33; P < .0001). No significant correlation was found between optimization of angiographic results with high pressure inflations and late luminal loss. Conclusions. Late expansion is a common phenome- non after Wallstent implantation and is mainly determi- ned by stent oversizing. Despite the fact that this pheno- menon is associated with greater neointimal proliferation, it seems to have a net beneficial effect on late luminal loss.