Intravascular ultrasound and stent implantation: Intraobserver and interobserver variability

Background Intravascular ultrasound (IVUS) imaging can be used to optimize implantation of intracoronary stents; the variability of the measurements, however, remains unclear. Our aim in this study was to determine the intrao bserver and interobserver variability of IVUS measurements after stent impl antation. Methods Ninety-four patients underwent implantation of 100 Palmaz-Schatz st ents in 98 lesions (79 de novo and 19 restenotic). IVUS measurements (3.5F, 30 MHz) of proximal and distal reference sections and of the smallest sten t lumen were performed by 2 investigators. Results Intraobserver and interobserver correlations, respectively, were r = 0.96 and 0.93 for the proximal reference, r = 0.94 and 0.92 for the dista l reference, and r = 0.97 and 0.97 for minimal stent lumen. Stent expansion (minimal lumen in the stent/mean reference area) showed a variability of r = 0.80 and 0.70. Taking a cutoff point of 90% for adequacy of stent expans ion,;observers agreed in only 77% whether the stent was adequately or inade quately expanded. Conclusions IVUS enables reproducible lumen measurements in stents and refe rence sections. The degree of stent expansion, however, underlies a high me asurement variability that can lead to different therapeutic strategies.