Stent design favorably influences the vascular response in normal porcine coronary arteries

Objectives. The purpose of this study was to compare the arterial response following implantation of a stainless-steel, balloon-expandable, tubular sl otted stent with that of a novel computer-designed, multi-cellular stent in normal porcine coronary arteries, Background. Intracoronary stent placement has evolved into the primary stra tegy for percutaneous revascularization of symptomatic coronary arterial le sions. Presently there is intense interest in developing new stent designs to improve stent delivery and biocompatability. Methods. Computer-assisted design was utilized to develop a balloon-expanda ble stent with symmetric expansion properties, uniform arterial wall covera ge, longitudinal flexibility and radial strength. Quantitative coronary ang iography and histological assessment of the stented arteries was used to ev aluate the acute and chronic vascular responses to a stainless-steel, ballo on-expandable, tubular slotted stent as compared to the computer-designed B X(TM) stent in the normolipemic swine. Results. Forty stents (24 EX, 16 tubular slotted) were implanted in 19 mini ature swine at a mean inflation pressure of 9 atm using identical delivery systems. Eight of the EX and none of the tubular slotted stents were post-d ilated with a non-compliant balloon at 12-14 atm. The mean stent-to-artery ratio was similar for the EX (1.03 +/- 0.06) and tubular slotted (1.04 +/- 0.11; p = 0.59) designs. Protrusion or asymmetric radial flaring of a strut at the stent margin was present in 1 of 23 EX stents (4.3%) and 10 of 15 t ubular slotted stents (66.7%; p < 0.0001). The mean arterial injury score w as significantly less for the EX stent (0.2 +/- 0.2) as compared with the t ubular slotted stents (0.4 +/- 0.4; p = 0.025). At 3 days, thrombus area wa s similar for the BX(TM) and tubular slotted designs (0.42 +/- 0.16 mm(2) v ersus 0.44 +/- 0.18 mm2, respectively; p = 0.88). The mean neointimal area was significantly less for the EX at 2 months (1.09 +/- 0.25 mm2 versus 2.9 3 +/- 2.26 mm(2) in the tubular slotted stent) and at 6 months (1.10 +/- 0. 26 mm(2) versus 2.07 +/- 0.65 mm(2) in the tubular slotted stent; p = (0.01 ), resulting in approximately 50% less in-stent stenosis. Conclusions. The arterial response to a balloon-expandable stent can be fav orably influenced by computer-assisted modification of design in an experim ental model. Further study is warranted to determine the impact of stent de sign upon clinical instent restenosis.