Saline infusion via local drug delivery catheters is associated with increased neointimal hyperplasia in a porcine coronary in-stent restenosis model

Background Catheter-based local drug delivery at the site of stent implanta tion has been proposed to reduce in-stent restenosis. We examined whether l ocal delivery itself may cause additional vessel wall injury and negate the potential benefit of local drug delivery in a porcine coronary in-stent re stenosis model. Methods Pigs were randomly assigned to no local delivery (controls, n = 10) or local saline infusion (5 ml) using commercially available catheters (n= 39; Dispatch catheter, Microporous Infusion catheter, and infusaSleeve) pri or to oversized (stent:artery ratio 1.2) coronary stent implantation. The a mount of in-stent neointima was evaluated 4 weeks later with angiography an d histology. Results There was no difference in vessel size or stent: artery ratio. Howe ver, at follow-up the local saline delivery group had significantly greater diameter stenosis (50 +/-19% versus 25 +/- 17% in the controls, P<0.01). H istology revealed similar injury scores but significantly greater neointima l area in the local saline group (3.61 +/- 1.11 mm(2) versus 1.96 +/- 0.82 mm(2) in the controls, P < 0.01). In a multivariate linear regression analy sis, the use of the local delivery catheter was the only independent variab le which was positively correlated with the amount of neointima (P = 0.0001 ). Conclusions in this in-stent restenosis model, catheter-based local saline delivery was associated with significantly increased neointimal hyperplasia Thus, for local drug delivery to reduce in-stent restenosis, the antiproli ferative agent should be potent enough to compensate for the additional neo intimal hyperplasia from the infusion itself. Coronary Artery Dis 10:629-63 2 (C) 1999 Lippincott Williams & Wilkins.