Optimizing stent expansion with new stent delivery systems

OBJECTIVES The purpose of this study was to assess whether the newer stent delivery systems provide a stented lumen cross-sectional area (CSA) that is equal to the delivery balloon nominal dimensions. BACKGROUND First generation stents were often not adequately expanded with their delivery system and frequently required higher pressure or a larger balloon after deployment. Newer stents were designed to optimize expansion with noncompliant, high-pressure balloons provided as the delivery systems. METHODS Intravascular ultrasound (IVUS) was used to evaluate 38 stents in 32 patients after deployment at 14 to 16 atm with their delivery balloon system. Minimum stent lumen CSA and stent minimum lumen diameter (MLD) were measured by IVUS imaging. The manufacturer’s expected stent diameter was defined as the balloon diameter measured by the company at the maximum pressure used. The manufacturer’s expected stent area was calculated based on the manufacturer’s expected stent diameter. RESULTS The MLD (2.5 ± 0.5 mm) and minimum stent CSA (6.0 ± 1.7 mm2) by IVUS were significantly smaller than the manufacturer’s expected stent diameter (3.5 ± 0.4 mm) and area (9.5 ± 1.9 mm2) (p < 0.0001, respectively). The mean MLD by IVUS was 72 ± 8% of the expected stent diameter, and the mean minimum stent CSA by IVUS was 62 ± 10% of the expected stent area. CONCLUSIONS Despite moderately high-pressure inflations, the mean minimum stent CSA actually achieved was, on average, only 62% of the manufacturer’s expected stent area. To optimize stent deployment, these IVUS observations should be considered during coronary artery stenting.