Association of plaque composition and vessel remodeling in atherosclerotic renal artery stenosis: a comparison with coronary artery disease

Abstract

Objectives: The current study was designed to investigate the relationship between renal arterial structure and vessel remodeling in patients with atherosclerotic renal artery stenosis (RAS), compared with that seen in coronary artery disease (CAD).

Background: The nature and the tissue characterization of atherosclerotic RAS lesions have not been fully explored.

Methods: Gray scale and virtual histology (VH) intravascular ultrasound imaging was used to assess 23 lesions in 14 consecutive RAS patients and 20 left main trunk lesions in age-matched CAD patients. Analysis included assessment of vessel area and atherosclerotic plaque area of the main renal artery or left main trunk. Plaque was characterized as fibrous tissue, fibro-fatty tissue, necrotic core, and dense calcium. Remodeling was assessed by means of the remodeling index (RI).

Results: Positive remodeling (defined as RI > or =1.05) was present in 15 RAS and 9 CAD lesions, whereas intermediate/negative remodeling (RI <1.05) was present in 8 RAS and 11 CAD lesions. VH showed that the fibrous tissue was the most prominent plaque composition, followed by fibro-fatty, necrotic core, and dense calcium in both vascular beds. Greater vascular adaptive enlargement was observed in slices with plaque burden < or =40% compared with plaque burden >40% (p < 0.001 for all). Vessel area had a positive association with the area of all VH components (p < 0.001, for all). VH analysis shows that the most powerful determinant of adaptive vessel enlargement is dense calcium in RAS (p < 0.001), while that is necrotic core in CAD (p < 0.001). Necrotic core and dense calcium areas were greater in lesions with positive remodeling compared with intermediate/negative remodeling (p = 0.03, p = 0.03, respectively, in RAS; p = 0.005, p = 0.03, respectively, in CAD).

Conclusions: The current study demonstrates in humans that plaque composition as assessed by VH intravascular ultrasound has an important role of adaptive vessel enlargement, and it is related to renal artery remodeling in RAS in a pattern similar to CAD.

Figure 1. Pie Diagram Describing the Distribution of VH Plaque Component

Virtual histology (VH) plaque components are displayed fibrous in red, fibro-fatty in yellow, dense calcium in white, and necrotic core in orange. (A) VH plaque components of renal artery stenosis (RAS) lesions. (B) VH plaque components of coronary artery disease (CAD) lesions. Fibrous plaque was the most prominent plaque composition, followed by fibro-fatty plaque, necrotic core, and dense calcium in both lesions.

Figure 2. Adaptive Vessel Enlargement for Different Plaque Burdens

Upper panels show the correlations between vessel area and plaque area in RAS lesions. (A) The adaptive vessel enlargement in slices with plaque burden <40% in RAS lesions. The degree of adaptive vessel enlargement is 1.11 mm². (B) In slices with plaque burden >40% in RAS lesions, the degree is 0.63 mm². Lower panels show the correlations in patients with CAD lesions. (C) In slices with plaque burden <40% in CAD lesions, the degree is 1.32 mm². (D) In slices with plaque burden >40% in CAD lesions, the degree is 0.83 mm². Abbreviations as in Figure 1.

Figure 3. Adaptive Vessel Enlargement for Plaque Components in RAS Lesions

Panels show the correlation between vessel area and virtual histology plaque components in renal artery stenosis (RAS) lesions. (A) The correlation between vessel area and the area of fibrous tissue. The degree adapting vessel enlargement is 0.52 mm². (B) The degree for fibro-fatty tissue is 0.42 mm². (C) The degree for necrotic core is 1.65 mm². (D) The degree for dense calcium is 4.33 mm².

Figure 4. Adaptive Vessel Enlargement for Plaque Components in CAD Lesions

Panels show the correlation between vessel area and virtual histology plaque components in coronary artery disease (CAD) lesions. (A) The correlation between vessel area and the area of fibrous tissue. The degree adapting vessel enlargement is 0.92 mm². (B) The degree for fibro-fatty tissue is 1.25 mm². (C) The degree for necrotic core is 2.01 mm². (D) The degree for dense calcium is 1.04 mm².

Figure 5. Examples of VH-IVUS Images in RAS Patients

Upper panels show a set of example of virtual histology-intravascular ultrasound imaging (VH-IVUS) images with negative remodeling. (A) The image at the site with minimum lumen area in the vessel with negative remodeling. (B) At the reference in the vessel with negative remodeling. Lower panels show a set of examples with positive remodeling. (C) At the minimum lumen area in the vessel with positive remodeling. (D) At the reference in the vessel with positive remodeling. RAS = renal artery stenosis.

Figure 6. Examples of VH-IVUS Images in CAD Patients

Upper panels show a set of example of virtual histology-intravascular ultrasound imaging (VH-IVUS) images with negative remodeling. (A) The image at the site with minimum lumen area in the vessel with negative remodeling. (B) At the reference in the vessel with negative remodeling. Lower panels show a set of examples with positive remodeling. (C) At the site with minimum lumen area in the vessel with positive remodeling. (D) At the reference in the vessel with positive remodeling. CAD = coronary artery disease.

Figure 7. Comparison of the Area of VH Plaque Components Between Remodeling Patterns

Intermediate/negative remodeling group is displayed in red bars and positive remodeling group is displayed in gold bars. (A) Comparison of the area of VH components in RAS lesions. (B) The percent area of VH components in RAS lesions. (C) The area of VH plaque components in CAD lesions. (D) The percent area of VH plaque components in CAD lesions. Abbreviations as in Figure 1.