RESTENOSIS FOLLOWING ELECTIVE IMPLANTATION OF SINGLE PALMAZ-SCHATZ STENTS IN DE-NOVO LESIONS IN NATIVE VESSELS

Background: Restenosis is the main limitation of long-term success aft er coronary angioplasty. Intracoronary stent implantation may reduce r estenosis by producing a larger initial lumen and eliminating recoil. The objective of this study was to determine the frequency of and feat ures associated with restenosis after elective single Palmaz-Schatz st ent implantation in de-novo lesions in native vessels. Methods: Eighty consecutive patients were studied. Angiographic follow-up was perform ed in 79 out of 80 (99%) 6.5+/-3.4 months after the procedure. Angiogr aphic measurements were performed using an automated computerized quan titative angio- graphic analysis system. Results: Restenosis (greater than or equal to 50% stenosis) at follow-up occurred in 26 out of 79 p atients (33%). The frequency of complex lesion morphology was higher ( 50% versus 19% American College of Cardiology/American Heart Associati on classification B2; P=0.005), the reference vessel diameter larger ( 3.0+/-0.5mm versus 2.8+/-0.6mm, P=0.049), and the lesion length longer (10.9+/-3.5 mm versus 8.5+/-3.5 mm, P=0.009) in the restenosis group compared with the non-restenosis group. The population was divided int o three groups according to the reference vessel diameter: (1) greater than 3.0 mm (n=27), (2) 2.5-3.0 mm (n=29), and (3) less than 2.5 mm ( n=22). Ope patient was excluded from this subgroup analysis because of difficulty in determining the reference vessel diameter before the pr ocedure. The restenosis rates were 52%, 37%, and 11%, respectively, fo r the three groups (P=0.02). The relative acute gain was greater in th e smaller vessels, (0.66 in the <2.5 mm vessels, 0.53 in the 2.5-3.0 m m vessels, and 0.48 in the >3.0 mm vessels; P=0.006). This was associa ted with a relative oversizing of the final stent balloon in the small er vessels (balloon-to-vessel ratio of 1.33 in the vessels <2.5 mm dia meter, 1.16 in the 2.5-3.0 mm vessels, and 0.98 in the >3.0 mm vessels ; P=0.001). Conclusion: The frequency of restenosis in single elective ly implanted Palmaz-Schatz stents in de-novo lesions in native vessels was 33%. The degree of restenosis was lower in smaller vessels, in wh ich a better initial result was associated with relative oversizing of the final stent balloon. More aggressive dilation within the stented segment may result in a lower restenosis rate.