Intimal hyperplasia thickness at follow-up is independent of stent size: A serial intravascular ultrasound study

The purpose of this study was to determine whether the thickness of the intimal hyperplasia (IH) layer that accumulates within Palmaz-Schatz stent is dependent on stent size. Intravascular ultrasound (IVUS) and quantitative angiographic (QCA) studies were performed after stent implantation and at follow-vp (5.4 +/- 3.8 months) in 161 patients with 177 lesions created with 221 Palmaz-Schatz stents. Stent and lumen cross-sectional area (CSA) were measured. IH CSA and thickness at. follow-vp were calculated and compared with stent CSA and circumference. Maximum IH CSA and thickness were measured at the smallest follow-up lumen CSA; mean IH CSA and thickness was averaged over the length of the stent. Maximum IH CSA measured 4.8 +/- 2.4 mm(2), and mean IH CSA measured 2.8 +/- 2.2 mm(2). Maximum IH thickness (at the smallest follow-up lumen CSA) measured 0.60 +/- 0.36 mm, and mean IH thickness lover the length of the stent) measured 0.30 +/- 0.19 mm. There was a weak, hut significant correlation between mean and maximum IH CSA verses stent CSA (r = 0.215, p <0.0001 and r = 0.355, p <0.0001, respectively). However, there was no correlation between mean or maximum IH thickness versus stent CSA (r = 0.018, p = 0.643 and r = 0.056, p = 0.463, respectively) or stent circumference (r = 0.002, p = 0.956 and r = 0.069, p = 0.361, respectively). IH thickness was found to be independent of the stent size. This explains the known higher frequency of restenosis in smaller stents compared with larger stents. (C) 1998 by Excerpta Medica, Inc.