Effect of stent design on reduction of elastic recoil: A comparison via quantitative intravascular ultrasound

The increase in minimum lumen diameter achieved by coronary stent placement can be further enhanced by reducing the immediate recoil that occurs after stent deployment. The effect of various stent designs - flexible coils, slotted tubes, and a locking stent - on minimization of postdilation stent recoil was evaluated using an in vitro model of circumferential compression. The stents were expanded to 7 atm (3.82 ± 0.02 mm); as pressure was reduced, lumen diameter and cross-sectional area (CSA) were determined by on-line intravascular ultrasound imaging (30 MHz) positioned inside the dilating balloon (n = 10-15 inflation-deflation cycles). Stent recoil was assessed by calculation of percent change in CSA from 7 atm to negative balloon pressure: -33.1 ± 5.6% (GR-II) and -22.4 ± 3.8% (Wiktor) in the coil stents; -20.0 ± 4.2% (JJIS coronary), -8.4 ± 2.6% (JJIS biliary), and -6.9 ± 1.5% (Multilink) in the slotted tube stents; and -1.9 ± 3.2% in the Navius ZR1 locking stent (P < 0.05 vs. Multilink, P < 0.0001 vs. others). A range of resistances to recoil is demonstrated by this model, with coil stent designs undergoing greater elastic recoil than slotted tube stent designs. The locking stent design demonstrated the greatest radial strength and the most reduction in elastic recoil.