Objectives: This study was designed to evaluate the changes in intrastent and angiographic dimensions when intravascular ultrasound imaging is used to direct the deployment of balloon-expandable Palmaz-Schatz stents in coronary arteries and saphenous vein grafts.
Background: Intravascular ultrasound provides more information than angiography in the imaging of intravascular structures. Previous studies have shown that obtaining a larger lumen (greater "acute gain") with coronary interventions such as stenting leads to less restenosis and subacute thrombosis. It is not clear whether the information obtained by intravascular ultrasound can be used to obtain a greater acute gain in lumen dimensions.
Methods: Forty consecutive patients undergoing Palmaz-Schatz stent implantation had intravascular ultrasound imaging performed after a good angiographic appearance was obtained. If the stent did not appear adequately expanded by intravascular ultrasound, or if the struts were poorly apposed to the arterial wall, further stent dilation with larger balloons or higher pressure inflations were performed. Twenty-nine patients had subsequent intravascular ultrasound imaging. Intrastent diameters and areas were compared from the initial to the final intravascular ultrasound studies.
Results: Of the 40 patients studied, only 5 (13%) had an adequate result by intravascular ultrasound despite an acceptable angiographic appearance in all patients. Six additional patients did not undergo subsequent intravascular ultrasound imaging. The other 29 patients all demonstrated a significant increase in intrastent minimal diameter (mean 19%), major diameter (11%) and cross-sectional area (34%) (p < 0.001 for all measurements).
Conclusions: The use of intravascular ultrasound imaging in the deployment of balloon-expandable Palmaz-Schatz stents leads to a significant increase in intrastent dimensions (greater "acute gain").