Background: Benefit of percutaneous revascularization for atherosclerotic renal artery stenosis (RAS) may be attenuated by distal embolization of atheroemboli. The purpose of this study was to characterize RAS plaque composition with intravascular ultrasound virtual histology (IVUS-VH) and to explore the relationship between plaque components and renal frame count (RFC) after renal revascularization.
Methods: Seventeen patients (75 ± 7.5 years; 18 lesions) undergoing RAS revascularization were included. Before stenting, automated IVUS-VH pullback (0.5 mm/sec) with analysis of the minimal luminal diameter (MLD) frame and entire atherosclerotic segment was performed. RFC was also determined before and after stenting.
Results: The VH component analysis of the segment demonstrated predominantly fibrous tissue (56.3 ± 11.4%), followed by necrotic core (21.8 ± 8.6%), dense calcification (13.2 ± 6.6%) and fibrofatty tissue (8.7 ± 4.0%). Analysis of the MLD frame also demonstrated mostly fibrous tissue (62.1 ± 11.1%), with smaller amounts of necrotic core (15.6 ± 7.3%), fibrofatty (13.9 ± 9.6%), and dense calcification (8.4 ± 6.0%). A trend toward more fibrous tissue (p = 0.074), less necrotic core (p = 0.095) and less dense calcification (p = 0.075) at the MLD compared to the segment was observed. Analysis of the entire atherosclerotic segment revealed a positive correlation between % necrotic core and change in RFC (r = 0.582; p = 0.029), with increasing necrotic core associated with an increase in RFC after revascularization.
Conclusion: Both the MLD frame and segmental analysis of atherosclerotic RAS lesions demonstrate predominantly fibrous tissue with smaller amounts of necrotic core, fibrofatty tissue, and dense calcification. Increased necrotic core correlates with a lack of improvement in RFC after stenting.