Adjunct high-pressure balloon inflations following the delivery of oversized self-expandable Wallstents may affect their implied late, postprocedural self-expansion. Consequently, we examined 15 "Magic" Wallstents, which were implanted following a strategy of stent oversizing and subsequent adjunct high-pressure balloon inflations (16 +/- 2 atm; all > or = 12 atm). The excellent radiographic visibility of this stent permitted reliable quantitative coronary angiographic measurement of both lumen and stent dimensions (before and after stenting, and at follow-up). At follow-up, extent and distribution of in-stent neointimal proliferation were evaluated with volumetric intravascular ultrasound. Between postintervention and follow-up examination, mean stent diameter increased from 3.7 +/- 0.4 to 4.2 +/- 0.4 mm (p <0.0001); there was no significant difference in late stent expansion between proximal, mid-, and distal stent subsegments. Late stent expansion showed a significant (reverse) relation to maximum balloon size (r = -0.56, p <0.04), but not with follow-up lumen size or late lumen loss. On average, 52 +/- 18% of the stent was filled with neointimal ingrowth; neointimal volume/cm stent length was 64 +/- 22 mm3. Both late stent expansion (r = 0.36, p <0.02) and maximum balloon pressure (r = 0.41, p <0.001) were related to neointimal volume/cm stent but not to follow-up lumen size. Thus, despite high-pressure implantation, Wallstents showed significant late self-expansion, which resulted in larger stent dimensions at follow-up that assisted in accommodating in-stent neointimal proliferation. Conversely, late stent expansion had a significant relation to the extent of in-stent neointimal ingrowth. Beneficial and disadvantageous effects of the late stent expansion appear to be balanced, because a relation to late lumen loss or follow-up lumen dimensions was not found to be present.

*Stents, Aged, Angioplasty, Balloon/*methods, Confounding Factors (Epidemiology), Coronary Angiography/methods, Coronary Disease/*therapy/ultrasonography, Female, Humans, Male, Middle Aged, Treatment Outcome, Ultrasonography, Interventional,
The American Journal of Cardiology
Erasmus MC: University Medical Center Rotterdam

von Birgelen, C, Airiian, S.G, Foley, D.P, van der Giessen, W.J, Serruys, P.W.J.C, & de Feyter, P.J. (1998). Coronary wallstents show significant late, postprocedural expansion despite implantation with adjunct high-pressure balloon inflations. The American Journal of Cardiology, 82(2), 129–134. doi:10.1016/S0002-9149(98)00317-8