RECOIL FOLLOWING WIKTOR STENT IMPLANTATION FOR RESTENOTIC LESIONS OF CORONARY-ARTERIES

The purpose of this study was to determine acute recoil of the vessel wall immediately after Wiktor stent implantation in native coronary ar teries of 77 consecutive patients and to assess whether there was comp ression or ''late recoil'' of the stent itself at long-term follow-up. Furthermore, the relationship between recoil and a number of clinical , angiographic, and procedural variables was studied in addition to th e relation between acute recoil renarrowing or restenosis was assessed . All angiograms were analyzed with the Cardiovascular Angiography Ana lysis System using automated edge detection. Acute recoil was defined by the difference between the mean diameter of the fully expanded ball oon on which the stent was mounted and the mean diameter of the stente d segment. Late recoil was calculated by comparing the mean diameter o f the stent itself immediately after implantation and at follow-up wit hout opacification of the vessel. Acute recoil amounted to 0.25 +/- 0. 32 mm or 8.2%. Multivariate analysis identified sex (coefficient = - 0 .20, p = 0.04) and stent/artery ratio (coefficient = 0.99, p = 0.0001) as the only independent predictors of acute recoil. ''Late recoil'' o f the stent itself was not observed. The overall difference between th e mean diameter of the stent itself immediately after implantation and at follow-up was -0.15 +/- 0.33 mm, suggesting an overall increase in diameter of 5.0%. There was no relation between acute recoil and late restenosis. On the contrary, there was a trend towards a greater degr ee of recoil in patients without restenosis. Moreover, linear regressi on analysis disclosed a weak but negative correlation between acute re coil and a loss in minimal luminal diameter (coefficient: -0.55, p = 0 .04). The Wiktor stent effectively scaffolds the instrumented vessel. Only a minimal amount of acute recoil was noted, which did not contrib ute to late luminal renarrowing or restenosis. In addition, no late co mpression of the stent itself was observed. These data suggest that ti ssue ingrowth into the lumen of the stented segment is the main cause of late luminal renarrowing after stent implantation. (c) 1994 Wiley-L iss, Inc.