Tissue proliferation within and surrounding Palmaz-Schatz stents is dependent on the aggressiveness of stent implantation technique

in-stent restenosis is entirely due to intimal hyperplasia. Histologic studies have indicated that intimal hyperplasia is related to the arterial injury induced during stent implantation. We used intravascular ultrasound (IVUS) imaging tb study whether tissue proliferation inside and surrounding stents is related to the aggressiveness of the implantation technique. After intervention and follow-up (mean 5.6 +/- 3.7 months), serial IVUS imaging was performed in 102 native artery stented stenoses in 91 patients. Measurements at 5 predetermined segments within each stented lesion included external elastic membrane stent and lumen cross-sectional areas (CSAs). Calculations included mean plaque CSA growth outside of the stent (external elastic membrane-stent) and mean neointimal hyperplasia CSA and thickness within the Stent (stent lumen). Stenoses were categorized depending on the aggressiveness of stent placement (group 1, adjunct percutaneous transluminal coronary angioplasty pressure <16 atm and/or balloon/artery ratio<1.1; group 2, adjunct percutaneous transluminal coronary angioplasty pressure greater than or equal to 16 atm and balloon/artery ratio greater than or equal to 1.1). An aggressiveness score was calculated as balloon/artery ratio inflation pressure. Mean intimal hyperplasia CSA (2.9 +/- 1.5 vs 2.2 +/- 1.6 mm(2), p = 0.028), mean intimal hyperplasia thickness (0.34 +/- 0.19 vs 0.25 +/- 0.19 mm, p = 0.012), and mean peristent tissue growth CSA (2.5 +/- 1.0 vs 1.1 +/- 1.4 mm(2), p = 0.003) were significantly greater in group 2 stenoses. In addition, intimal hyperplasia CSA and thickness correlated significantly with balloon/artery ratio inflation pressures: r = 0.305, p = 0.002 and r = 0.329, p = 0.0007, respectively, as did peristent tissue proliferation CSA (r = 0.466, p = 0.001). Tissue proliferation inside and surrounding stents may be related to aggressiveness of the stent implantation technique. (C)1999 by Excerpta Medica, Inc.