Assessment of internal carotid artery stenosis and results of carotid stenting by angiography compared with intravascular ultrasound

Abstract Background/Introduction Intravascular imaging is commonly used in coronary interventions and improves outcomes. On the contrary, it is almost unrecognized for the guidance of carotid stenting (CAS). Purpose The aim of this study was to compare quantitative angiography (QA) and intravascular ultrasound (IVUS) in the assessment of the severity of carotid stenosis and residual stenosis in patients undergoing CAS and to provide reference values for IVUS measurements of the internal carotid artery (ICA) in the European population. Methods IVUS imaging was performed during 151 CAS procedures in 140 patients from April 2013 to December 2019. In total 162 self-expanding stents of different design were implanted (66% closed-cell, 22% open-cell, 8% hybrid, 4% double layer micromesh stents). IVUS was used to measure distal reference diameter and area of ICA, minimal luminal diameter (MLD) and minimal luminal area (MLA) before and after CAS. IVUS and QA were used to measure relative stenosis area (stenosis) at baseline and relative residual stenosis area (residual stenosis) after CAS. Relative stenosis area was calculated as [1 − (MLA / distal reference area)] x 100. Results Mean (±SD) distal reference diameter of ICA was 4.5±0.8 mm. MLD increased from 1.9±0.4 mm to 3.6±0.6 mm after CAS (p<0.001). MLA increased from 3.9±1.7 mm2 to 12.0±3.4 mm2 after CAS (p<0.001). Stenosis measured by QA and IVUS was 84±9% and 76±13% respectively (p=0.01). There was a moderate correlation (Pearson's correlation coefficient r=0.575; p=0.01) between QA and IVUS measurement of ICA stenosis severity. Residual stenosis measured by QA and IVUS was 12±10% and 40±16% (p<0.001) respectively with only weak correlation (r=0.433; p<0.001) between the two methods. Conclusion Angiography slightly overestimates stenosis of internal carotid artery and substantially underestimates residual stenosis after CAS compared to IVUS. Angiography alone is inaccurate in the assessment of ICA stenosis and results of carotid stenting. Funding Acknowledgement Type of funding source: Public hospital(s). Main funding source(s): University Hospital Motol