Insertion of Self-Expandable Nitinol Stents Without Previous Balloon Angioplasty Reduces Restenosis Compared with PTA Prior to Stenting.

Abstract

Purpose: To compare the development of intimal hyperplasia after deployment of a self-expanding nitinol stent with and without previous percutaneous transluminal balloon angioplasty (PTA), with the results after PTA alone. Methods: In nine healthy pigs, the iliac arteries were divided into three groups: group 1 (n = 6 arteries) was treated with PTA; group 2 n = 6) with insertion of self-expanding stents after PTA; and group 3 (n = 6) with stent insertion without previous PTA. After 8 weeks the vessels were examined with intravascular ultrasonography, histologic examination and morphometric analysis. Results: Although the injury index in group 1 (0.17 +/- 0.57) was lower (p <0.05) than in group 2 (0.26 +/- 0.06) and group 3 (0.26 +/- 0.08), PTA-treated arteries showed significantly (p <0.05) reduced mean luminal gain (0.53 +/- 2.84) compared with arteries treated with PTA prior to stenting (2.58 +/- 1.38) and compared with stenting alone (4.65 +/- 5.34). Stenting after PTA resulted in a higher (p <0.05) restenosis index (2.63 +/- 1.06) compared with stenting without PTA (1.35 +/- 0.59). Group 2 also had a significantly thicker intima p <0.05) and 83% and 74% higher intima/media ratio (p <0.05) compared with groups 1 and 3, respectively. Conclusion: Insertion of a self-expandable nitinol stent without previous PTA results in less intimal hyperplasia than if PTA is performed prior to stenting, suggesting that direct stenting can be used in angioplasty sessions with a favorable outcome