Coronary lumen at six-month follow-up of a new radiopaque cordis tantalum stent using quantitative angiography and intracoronary ultrasound

To determine the reliability of geometric (edge-detection) quantitative coronary angiographic analysis (QCA) of restenosis within a new Cordis tantalum stent, QCA and intracoronary ultrasound (ICUS) measurements were compared in both an experimental restenosis model and in the clinical follow-up of patients. In the experimental series, Plexiglas^TM phantom vessels with concentric stenosis channels ranging from 0.75 to 3.0 mm in diameter and with a reference diameter of 3.0 mm were imaged both before and after their insertion in tantalum stents. In the clinical series, the agreement of QCA and ICUS measurements were studied in 23 patients who had undergone coronary implantation of the new tantalum stent and in 23 patients who had undergone balloon angioplasty 6 months previously. The reliability of QCA declined in the presence of the radiopaque stent (accuracy of QCA decreased from -0.07 to -0.12 mm), whereas the reliability of lumen measurements by ICUS was independent of the presence of the radiopaque stent (-0.12 and -0.13 mm). Without the stent, the average minimal luminal diameter (MLD) obtained by QCA of the 1.00 mm Plexiglas vessel was 1.00 ± 0.01 mm, and the 3.00 mm reference vessel diameter was 2.81 ± 0.05 mm, providing a 64 ± 1% diameter stenosis. After introduction of the stent, the average MLD and reference vessel diameter were 0.99 ± 0.06 and 3.36 ± 0.17 mm, respectively, providing a diameter stenosis of 71 ± 2%. ICUS measurements (2.77 mm) of the reference vessel diameter (3.00 mm) were unaffected by the presence of the stent. Agreement of ICUS and QCA measurements (ICUS - QCA) was poorer in patients who had undergone balloon angioplasty (0.68 ± 0.42 mm) than in patients who had stent implantation (-0.05 ± 0.42 mm). In the 6-month follow-up of patients who had undergone implantation of a highly radiopaque Cordis tantalum stent, assessment of restenosis was reliably quantified by QCA with the use of the MLD rather than the percent diameter stenosis. Although ICUS measurements are unaffected by the radiopaque stent, the mechanical problem of ICUS catheter wedging in stenoses of < 1.00 mm and the substantial cost of ICUS catheters will restrict the widespread application of ICUS for the assessment of intrastent restenosis.