Coronary stents: In vitro aspects of an angiographic and ultrasound quantification with in vivo correlation

The validity of quantitative coronary angiography (QCA) after stent placement has been questioned because the optical density of a metallic stent, added to the density of a contrast-filled lumen, could affect border definition.

We deployed 3.0- and 4.0-mm Palmaz-Schatz, Wiktor, Multilink, NIR, and InStent stents in precision-cast phantoms. Central lumens of 2.0 mm were created. There was no difference between the "true" diameters of any stented lumen by both QCA and quantitative ultrasonic (QCU) measurement poststenting. QCA systematic error (SE) varied from 0.01 for the Wiktor stents to 0.14 mm for the Palmaz-Schatz stents; the random error (RE) was 0.03 to 0.14 mm. QCU SE varied from 0.05 to 0.11 mm, and RE ranged from 0.01 to 0.07 mm. At the next stage, 4.0-mm Wiktor and Palmaz-Schatz stents were deployed into the phantom lumens; 1.5-, 2.0-, 2.5- and 3.0-mm lumens were created inside the stents. QCA and QCU measurements of 1.5- to 2.5-mm residual lumens were overestimated by 0.1 to 0.3 mm. In the 3. 0-mm residual lumen within the Wiktor stent, QCA underestimated the luminal size by -0.1 mm. There was no QCA inaccuracy for a 3.0-mm lumen within the Palmaz-Schatz stent. In patients, in 25 stented segments in both the Palmaz-Schatz and Wiktor groups, there was no difference between QCA and QCU diameters.

QCU is sufficiently precise for the assessment of the coronary lumen after stenting. QCA can be used as an accurate method of poststent assessment, except when a very mild recurrence within a highly opaque stent is measured. In that instance, QCA may underestimate the luminal diameter.