Prospective Comparison of Duplex Ultrasound and Angiography for Intra-operative Completion Studies after Carotid Endarterectomy

Abstract

Objective: The application of intra-operative completion studies may have contributed to the ongoing improvement of peri-operative outcomes in carotid surgery.

Methods: This prospective study aimed to compare angiography and duplex ultrasound (IDUS) as intra-operative completion studies after carotid endarterectomy (CEA) with respect to differences in the rating of vessel wall defects and interobserver reliability. Patients undergoing CEA for symptomatic or asymptomatic carotid stenosis were included. After CEA, angiography and IDUS were performed. Intra-operatively obtained video footage was evaluated at a later date by three independent and blinded raters with different levels of clinical experience. Rating was done according to a four step rating scale, with higher grades representing more severe defects. Standard statistical methods (Pearson's chi square test; permutation test; Wilcoxon signed rank test; Kendall's coefficient of concordance, Wt) were applied.

Results: In total, 150 patients (mean ± standard deviation age 72 ± 7 years, 68.7% male, 33.3% symptomatic) were enrolled between March 2016 and September 2017. Significantly more defects requiring intra-operative revision (grades 3 and 4 on rating scale) were detected by IDUS, which, in part, remained undetected by angiography: 22 (14.7%) vs. 10 (6.7%) (p = .040). Defects were also judged to be more severe with IDUS than with angiography: median rating grade 1: 74 (49.3%) vs. 102 (68.0%); grade 2: 54 (36.0%) vs. 38 (25.3%); grade 3: 21 (14.0%) vs. 9 (6.0%); grade 4: 1 (0.7%) vs.1 (0.7%) (p < .001). Furthermore, Wt was significantly higher for IDUS compared with angiography (0.70 vs. 0.57; p = .003).

Conclusion: IDUS revealed more defects after CEA than angiography. Despite both techniques only showing moderate interobserver reliability, IDUS is less dependent on the surgeon's subjectivity than angiography. Taking into account the absence of procedure associated risks (i.e., adverse effects of iodinated contrast media and Xray), IDUS could be considered as an alternative intra-operative morphological assessment tool in carotid surgery.

Keywords: Angiography; Carotid; Endarterectomy; Ultrasound.