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

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OBJECT

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

The long-term morphological outcome of primary carotid stenting was predicted with considerable accuracy by using a straightforward CTA carotid plaque grading scale.

ABBREVIATIONSCAS = carotid angioplasty and stenting; CEA = carotid endarterectomy; CREST = Carotid Revascularization Endarterectomy versus Stent Trial; CTA = CT angiography; EPD = embolic protection device; NASCET = North American Symptomatic Carotid Endarterectomy Trial; PCS = primary carotid stenting; PLAC = Predicting Long-term outcome with Angioplasty of the Carotid artery; PSV = peak systolic velocity; SES = self-expanding stent.
Article Information

Contributor Notes

Correspondence David M. Pelz, Department of Medical Imaging, University Hospital, London Health Sciences Centre, 339 Windermere Rd., London, ON N6A 5A5, Canada. email: pelz@uwo.ca.INCLUDE WHEN CITING Published online March 27, 2015; DOI: 10.3171/2014.9.JNS14811.DISCLOSURE The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

© AANS, except where prohibited by US copyright law.

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