Defining carotid near-occlusion with full collapse: a pooled analysis

Abstract

Purpose: Create a new definition of near-occlusion with full collapse to predicting recurrent stroke.

Methods: Pooled analysis of two studies. Patients with symptomatic ≥ 50% carotid stenoses were included. Outcome was preoperative recurrent ipsilateral ischemic stroke or retinal artery occlusion within 28 days of presenting event. We analyzed several artery diameters on computed tomography angiography and stenosis velocity on ultrasound.

Results: A total of 430 patients with symptomatic ≥ 50% carotid stenosis were included, 27% had near-occlusion. By traditional definition, 27% with full collapse and 11% without full collapse reached the outcome (p = 0.047). Distal internal carotid artery (ICA) diameter, ICA ratio, and ICA-to-external carotid artery ratio were associated with the outcome. Best new definition of full collapse was distal ICA diameter ≤ 2.0 mm and/or ICA ratio ≤ 0.42. With this new definition, 36% with full collapse and 4% without full collapse reached the outcome (p < 0.001).

Conclusions: Defining near-occlusion with full collapse as distal ICA diameter ≤ 2.0 mm and/or ICA ratio ≤ 0.42 seems to yield better prognostic discrimination than the traditional appearance-based definition. This novel definition can be used in prognostic and treatment studies of near-occlusion with full collapse.

Keywords: CT-angiography; Carotid near-occlusion; Carotid stenosis; Stroke; Ultrasound.

Fig. 1

Carotid near-occlusions, coronal views. a Right-sided near-occlusion without full collapse. Beyond a severe stenosis (white arrowhead), the distal ICA is normal-appearing (white arrow, diameter 2.8 mm). However, the distal ICA is smaller than contralateral ICA (black arrowhead, ICA ratio 0.72) and similar to ipsilateral ECA (black arrow, ECA ratio 0.97). It was classified as without full collapse with all presented definitions. b Right-sided near-occlusion with full collapse. Beyond a severe and calcified stenosis (white arrowheads), the distal ICA has a threadlike appearance (white arrow, diameter 1.2 mm), clearly smaller than both contralateral ICA (black arrowhead, ICA ratio 0.20) and ipsilateral ECA (black arrow, ECA ratio 0.40). It was classified as with full collapse with all presented definitions

Fig. 2

Kaplan–Meier curves of three approaches to define near-occlusion with full collapse. Tests for statistical significance presented in Tables 3 and 5. a Traditional approach. b Distal ICA diameter ≤2.4 mm. c Distal ICA diameter ≤ 2.0 mm and/or ICA ratio ≤ 0.42. The outcome was preoperative recurrent ipsilateral ischemic stroke or ipsilateral retinal artery occlusion