Whys and Wherefores of Coronary Arterial Positive Remodeling

Abstract

Positive remodeling (PR) is an atherosclerotic plaque feature defined as an increase in arterial caliber at the level of an atheroma, in response to increasing plaque burden. The mechanisms that lead to its formation are incompletely understood, but its role in coronary atherosclerosis has major clinical implications. Indeed, plaques with PR have elevated risk of provoking acute cardiac events. Hence, PR figures among the high-risk plaque features that cardiac imaging studies should report. This review aims to provide an overview of the current literature on coronary PR. It outlines the pathophysiology of PR, the different techniques used to assess its presence, and the imaging findings associated to PR, on both noninvasive and invasive studies. This review also summarizes clinical observations, trials, and studies, focused on the impact of PR on clinical outcome.

Keywords: atherosclerosis; cardiac imaging techniques; coronary angiography; coronary vessels; diagnostic imaging.

Figure 1.

Remodeling by plaque type. The internal elastic lamina (IEL) increase, adjusted for plaque area, is plotted by plaque type. Plaque hemorrhage, including plaque rupture, showed significantly greater remodeling than fibrous plaque (stable; P=0.03) and total occlusion (P=0.03); the test used is ANOVA. Data derived from Burke et al.

Figure 2.

A 55-year-old male patient who died suddenly without any medical history. Autopsy, micro-computed tomography (micro-CT) after coronary perfusion fixation, and histological findings at 3- to 4-mm intervals (the coronary arteries were removed from the heart, perfusion fixed, and then the specimen was imaged with X-ray micro-CT, Nikon XTH 225 ST PE1621 EHS system using a tungsten target at 95 keV and 89 µA with 1200–1800 projections of 500 ms each resulting in a 20- to 30-minute scan with a resolution ranging between 18.4 and 23.1 µm). The scans were reconstructed using Core Imaging Library 23.1.0 and postprocessed in ImageJ/Fiji 1.54h and 3D Slicer 5.4.0. A, Plaque rupture at the proximal right coronary artery (RCA). The proximal end is on the right, and the distal segment is on the left. The orange lines indicate where the sections were taken showing positive remodeling, and the corresponding histological sections show the area of plaque rupture in RCA 4. Note this section is the most remodeled with mild calcification and a large necrotic core. Section labeled RCA 5 shows total occlusion and RCA 6 shows organized thrombus with severe narrowing of the lumen. B, Thin-cap fibroatheroma (TCFA) of the left anterior descending (LAD). The midsection of the LAD is shown with the left diagonal coming off the LAD (above). The orange lines indicate where the sections were taken showing positive remodeling, with maximum remodeling in LAD 10, and the corresponding histological sections show the area of TCFA in sections LAD 8 to LAD 10. Images RCA 4 and LAD 10: data derived from Jinnouchi et al. LD indicates left diagonal.

Figure 3.

Male patient with multiple cardiovascular risk factors at baseline and follow-up. A, A 41-year-old male patient with multiple cardiovascular risk factors and mild atherosclerosis of the left circumflex (LCx). B, Seven years later, the patient presented with unstable angina. Percutaneous coronary intervention revealed severe stenosis of the mid portion of LCx (white arrow). Intravascular ultrasound images of the segment proximal to the stenosis are shown above; note the presence of a nonobstructive atherosclerotic plaque with positive remodeling (white arrowheads) and ulceration (yellow arrowhead). Optical coherence tomography, performed at the same level, is shown below; note the presence of thin-cap fibroatheroma (yellow arrowhead) and necrotic core (white arrowhead).

Figure 4.

Coronary computed tomography angiography images of a 68-year-old male patient presenting with chest pain to the emergency department and multiple risk factors for coronary artery disease. Images show a calcified atherosclerotic plaque in the proximal left anterior descending (LAD) with positive remodeling with mild stenosis, ≈30% (white arrow). Coronary plaque analysis was performed with a semiautomatic software (vascuCAP; Elucid Bioimaging, Wenham, MA). Software analysis provides coronal, axial, and sagittal views, as well as 3-dimensional (3D) and curved planar reformation (CPR) straightened views. Software output includes remodeling ratio (RR), percent dilation, and percent stenosis, which in this case were 3.15, 285%, and 17%, respectively. Curved multiplanar reformation of the LAD is shown on the right. Max indicates maximum; and MPR CV, multiplanar reformation curved view.