Plaque morphology (the PLAC Scale) on CT angiography: predicting long-term anatomical success of primary carotid stenting

• Published in: Journal of neurosurgery Vol. 123; no. 4; pp. 856 - 861
• Main Authors: Pelz, David M, Lownie, Stephen P, Lee, Donald H, Boulton, Melfort R
• Format: Journal Article
• Language: English
• Published: United States 01-10-2015
• Subjects: Aged; Aged, 80 and over; Angiography - methods; Carotid Stenosis - diagnostic imaging; Carotid Stenosis - pathology; Carotid Stenosis - surgery; Humans; Middle Aged; Prognosis; Remission Induction; Retrospective Studies; Stents; Time Factors; Tomography, X-Ray Computed; CAS = carotid angioplasty and stenting; carotid stenting; CREST = Carotid Revascularization Endarterectomy versus Stent Trial; PLAC = Predicting Long-term outcome with Angioplasty of the Carotid artery; plaque morphology; EPD = embolic protection device; PSV = peak systolic velocity; vascular disorders; NASCET = North American Symptomatic Carotid Endarterectomy Trial; CTA = CT angiography; CT angiography; carotid stenosis; SES = self-expanding stent; CEA = carotid endarterectomy; PCS = primary carotid stenting
• ISSN: 0022-3085; 1933-0693
• DOI: 10.3171/2014.9.jns14811

Carotid angioplasty and stenting has emerged as an alternative to carotid endarterectomy for the treatment of atherosclerotic carotid stenosis. Primary carotid stenting, performed using self-expanding stents alone without deliberate use of embolic protection devices and balloon angioplasty, has been shown to be effective and faster, cheaper, and potentially safer than conventional techniques. However, the long-term morphological results of this technique have not been established. The aim of this study was to determine whether preprocedural carotid plaque imaging at the site of maximal stenosis by using CT angiography (CTA) could predict the long-term morphological outcome of primary carotid stenting.
One hundred eighty-one patients were treated over an 11-year period. Preprocedural CTA was performed in 102 of these. A morphological scale (the Predicting Long-term outcome with Angioplasty of the Carotid artery [PLAC] Scale), with grades from 0 to 4 and A or B, was used to evaluate the circumferential degree of plaque calcification, and the presence or absence of soft plaque. All patients were followed using duplex carotid ultrasound and plain radiographs. Satisfactory morphological outcome was defined as a peak systolic velocity < 120 cm/s and internal carotid artery/common carotid artery ratio < 1.4.
The average follow-up duration was 29.7 months (median 24.5 months, range 0.3-87 months). Univariate logistic regression demonstrated that a low calcification grade (p < 0.001), less thick calcification (p < 0.001), and moderate amounts of soft plaque (p < 0.001) are factors that are highly associated with good long-term outcome. Multivariate analyses confirmed that these factors are independent of each other in predicting outcome.
The long-term morphological outcome of primary carotid stenting was predicted with considerable accuracy by using a straightforward CTA carotid plaque grading scale.