Biomechanical aspects of potential stent malapposition at coronary stent implantation

Abstract

Despite of the clearly improved restenosis rates with drug-eluting stents (DES), optimization of stent deployment is still important for favourable immediate and long-term results. This requirement is fed by the recently reported potential risk of late stent thrombosis which is among other factors assumed to be caused by stent malapposition. Stent malapposition appears frequently in clinical practice for DES as well as bare-metal stents (BMS). Our study investigated the biomechanical process of stent implantation by measuring stent/balloon profile during stent expansion, the remaining profile after balloon removal (elastic recoil), stent systems pressure-diameter characteristics (compliance) as well as the radial strength and stiffness of nine different modern BMS. It was found that the elastic recoil (3.60 to 6.87%) and stent system compliance (0.95 to 2.29%/bar) were the most critical parameters with regard to stent malapposition. The stent profiles at nominal pressure varied within a range of -0.097 to +0.294 mm. It is concluded that an accurate measurement of target vessel diameter as a basic criterion for selection of stent system is necessary as well as considering the compliance and elastic recoil data of the individual stent systems. Semi-compliant systems may cover a broader range of target diameters.