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Updated: Sep 25, 2026
Imaging In-Stent Restenosis: An Inexpensive, Reliable, and Rapid Preclinical Model
Published on: September 14, 2009
Intravascular ultrasound and quantitative coronary angiography assessment of late in-stent restenosis: in vivo human
Francesco Prati1, Tomasz Pawlowski, Luigi Sommariva
1San Giovanni Hospital, Rome, Italy. f.prati@libero.it
Insights
Intravascular ultrasound (IVUS) accurately measures in-stent neointimal hyperplasia, correlating well with quantitative coronary angiography (QCA). IVUS requires fewer patients than QCA for studies on reducing in-stent restenosis.
Area of Science:
- Cardiovascular Imaging
- Interventional Cardiology
- Biomedical Engineering
Background:
- Quantitative coronary angiography (QCA) assesses in-stent restenosis but indirectly estimates neointimal formation.
- Intravascular ultrasound (IVUS) directly measures in-stent neointimal hyperplasia (IH), a key factor in restenosis.
Purpose of the Study:
- Correlate IVUS-measured IH with QCA indexes of restenosis.
- Determine if QCA is a reliable surrogate for IVUS.
- Calculate sample sizes for clinical trials using QCA or IVUS data.
Main Methods:
- Retrospective analysis of 131 stented native coronary arteries from the European Imaging Laboratory database.
- Serial QCA and IVUS assessments at 6 months post-intervention.
- Linear regression to correlate IVUS mean % IH CSA with QCA % DS and late loss.
Main Results:
- Strong positive correlation found between IVUS mean % IH CSA and QCA % DS (r=0.74) and late loss (r=0.72).
- IVUS-based sample size: 74 stents for 80% power.
- QCA-based sample size (late loss): 230 stents for 80% power.
Conclusions:
- QCA measurements of restenosis correlate well with IVUS-derived neointimal formation.
- IVUS enables significantly smaller sample sizes for restenosis reduction studies.
- IVUS is recommended for comparative studies focusing on neointimal differences in smaller populations.
Abstract:
Quantitative coronary angiography (QCA) is routinely used for assessment of strategies aimed at reducing in-stent restenosis. Yet QCA enables only the measurement of luminal variation of stented segments and, unlike intravascular ultrasound (IVUS), provides only an indirect estimation of late in-stent neointimal formation, which has a key role in the process of in-stent restenosis. The aims of the present study were to correlate the IVUS measurement of in-stent intimal hyperplasia (IH) with QCA indexes of restenosis, to find out whether QCA is an adequate surrogate of IVUS, and, using either QCA and IVUS data, to define the sample sizes needed to demonstrate the effectiveness of strategies to reduce in-stent restenosis. The database of the European Imaging Laboratory was used to screen 154 stents implanted between 1997 and 2001 and studied by IVUS at 6 +/- 1 months of follow-up. All cases underwent serial QCA assessment (preintervention, postintervention, and follow-up). Only 131 cases with single stent implantation in native coronary arteries were included in the study. Stent restenosis, defined as percent diameter stenosis (DS) > 50%, was present at QCA in 69 out of 131 cases (53%). Linear regression analyses were performed to correlate the amount of IH, calculated by IVUS as the average of all cross-section areas (CSA; mean % IH CSA) and QCA indexes of restenosis (late loss and % DS). A positive significant correlation was found between IVUS mean % IH CSA and QCA % DS (r = 0.74; P < 0.0001) and between IVUS mean % IH CSA and QCA late loss (r = 0.72; P < 0.0001). Based on IVUS measurements of mean % IH CSA, a total sample size of 74 stents would be required in a two-arm comparison to have 0.80 power to detect at 0.05 significant level a 30% difference between two compared groups. Alternatively, adopting the QCA late loss, 230 stents would be required. QCA measurements of late in-stent restenosis are well correlated with IVUS calculation of in-stent neointimal formation. IVUS assessment of IH allows smaller sample sizes than QCA to document significant reductions of in-stent restenosis. Therefore, the use of IVUS should be encouraged in comparison studies aimed at revealing significant neointimal differences in small sample size populations.
