Intravascular ultrasonographic evaluation of direct stents, implanted without predilatation. Comparison of results according to lesion types

Introduction. Direct stenting is a safe and feasible technique in selected lesions yielding excellent angiographic results. However, there are no stud ies providing intravascular ultrasonographic examination after direct stent ing. The aim of this study was to evaluate direct stent expansion with ultr asonography and to know whether there are differences in the results based on lesion types. Methods. Patients with amenable lesions for direct stenting were enrolled; including patients with no occlusion, no calcification, no significant tort uosity or angulation, a length less than or equal to 15 mm and a reference lumen diameter greater than or equal to2.5 mm. Intra vascular ultrasonograp hy was performed after stent implantation. The ultrasonographic criteria fo r optimal expansion were: complete apposition and a minimal intrastent lume n area >80% of the average reference luminal area and greater than or equal to 90% of the distal reference lumen area. Results. We included 40 patients (50 lesions). The final angiographic resul t was good in all the patients but in one case an additional stent was used due to dissection. The ultrasonographic examination did not show significa nt differences between type A and B lesions. Optimal expansion was achieved in 14/21 (66%) of type A lesions and 17/29 (58%) of type B lesions (p = 0. 5). The balloon/artery ratio was the only factor significantly related to u ltrasonographic results. When this ratio was 1.1-1.2 (25 cases), 76% of the stents were optimally expanded and when the ratio was <1.1 (25 cases) only in a 48% an optimal result was achieved (p < 0.05). Conclusions. Direct stenting in selected lesions provides ultrasonographic results comparable to those expected with conventional stenting and these r esults could be even improved if a balloon artery ratio 1.1-1.2 is used. Ta king into consideration the selection criteria the differences observed bet ween lesion types A and B are not significant.