Carotid Near-Occlusion: A Comprehensive Review, Part 2--Prognosis and Treatment, Pathophysiology, Confusions, and Areas for Improvement

Carotid Near-Occlusion: Surgical or Conservative Management? Retrospective Multicenter Study

BACKGROUND

Carotid near-occlusion (CNO) represents an anatomical-functional condition characterized by severe (more than 90%) internal carotid artery stenosis which can lead to a distal lumen diameter greater or less than 2 mm. CNO can be divided into a less severe subgroup (without lumen full collapse: diameter >2 mm) and a more severe subgroup (with lumen full collapse: diameter <2 mm). The decision for revascularization is still highly debated in Literature. The aim of the present multicenter retrospective study is to analyze the incidence of perioperative (30 days) and follow-up complications in 2 groups of patients with or without distal internal carotid lumen full collapse.

METHODS

Between January 2011 and March 2023, in 5 Vascular Surgery Units, 67 patients (49 male, 73% and 18 females, 27%) with CNO underwent carotid endarterectomy: 28 (41.7%) with lumen diameter <2 mm and 39 (58.3%) with diameter >2 mm. 19 patients were symptomatic and 48 asymptomatic. The outcomes considered for comparative analysis were: perioperative neurological and cardiac complications, carotid restenosis or occlusion at follow-up. Both groups were homogeneous in terms of risk factors, morphological features and pharmacological treatments.

RESULTS

In the group with lumen <2 mm, 3 perioperative major events (10.7%) occurred (1 ischemic stroke, 1 hemorrhagic stroke, 1 myocardial infarction) and 2 (7.1%) at follow-up (average 11 ± 14.5 months; 1 asymptomatic carotid occlusion, 1 hemodynamic restenosis treated with stenting). No event was recorded in the group with lumen >2 mm.

CONCLUSIONS

According to our results CNO patients show different complication risk according to the presence or not of distal lumen collapse. The later seems to play a significant role in perioperative and follow-up complication rate. These results therefore support a surgical treatment only in patients with CNO without lumen full collapse.

Phase-contrast magnetic resonance imaging of intracranial and extracranial blood flow in carotid near-occlusion

PURPOSE

Compare extracranial internal carotid artery flow rates and intracranial collateral use between conventional ≥ 50% carotid stenosis and carotid near-occlusion, and between symptomatic and asymptomatic carotid near-occlusion.

METHODS

We included patients with ≥ 50% carotid stenosis. Degree of stenosis was diagnosed on CTA. Mean blood flow rates were assessed with four-dimensional phase-contrast MRI.

RESULTS

We included 110 patients of which 83% were symptomatic, and 38% had near-occlusion. Near-occlusions had lower mean internal carotid artery flow (70 ml/min) than conventional ≥ 50% stenoses (203 ml/min, P < .001). Definite use of ≥ 1 collateral was found in 83% (35/42) of near-occlusions and 10% (7/68) of conventional stenoses (P < .001). However, there were no differences in total cerebral blood flow (514 ml/min vs. 519 ml/min, P = .78) or ipsilateral hemispheric blood flow (234 vs. 227 ml/min, P = .52), between near-occlusions and conventional ≥ 50% stenoses, based on phase-contrast MRI flow rates. There were no differences in total cerebral or hemispheric blood flow, or collateral use, between symptomatic and asymptomatic near-occlusions.

CONCLUSION

Near-occlusions have lower internal carotid artery flow rates and more collateral use, but similar total cerebral blood flow and hemispheric blood flow, compared to conventional ≥ 50% carotid stenosis.

High risk of early recurrent stroke in patients with near-occlusion with full collapse of the internal carotid artery

We aimed to validate the prognostic ability and assess interrater reliability of a recently suggested measurement-based definition of near-occlusion with full collapse (distal ICA diameter ≤ 2.0 mm and/or ICA ratio ≤ 0.42). 118 consecutive patients with symptomatic near-occlusion were prospectively included and assessed on computed tomography angiography by 2 blinded observers, 26 (22%) had full collapse. At 2 days after presenting event, the risk of preoperative stroke was 3% for without full collapse and 16% for with full collapse (p = 0.01). At 28 days, this risk was 16% for without full collapse and 22% for with full collapse (p = 0.22). Interrater reliability was perfect (kappa 1.0). Thus, near-occlusion with full collapse should be defined as distal ICA ≤ 2.0 mm and/or ICA ratio ≤ 0.42 in order to detect cases with very high risk of early stroke recurrence.

Cerebral Blood Flow Patterns in Patients With Low-Flow Carotid Artery Stenosis, a 4D-PCMRI Assessment

BACKGROUND

Compromised cerebral blood flow can contribute to future ischemic events in patients with symptomatic carotid artery disease. However, there is limited knowledge of the effects on cerebral hemodynamics resulting from a reduced internal carotid artery (ICA) blood flow rate (BFR).

PURPOSE

Investigate how reduced ICA-BFR, relates to BFR in the cerebral arteries.

STUDY TYPE

Prospective.

SUBJECTS

Thirty-eight patients, age 72 ± 6 years (11 female).

FIELD STRENGTH/SEQUENCE

3-Tesla, four-dimensional phase-contrast magnetic resonance imaging (4D-PCMRI).

ASSESSMENT

Patients with ischemic stroke or transient ischemic attack were evaluated regarding the degree of stenosis. 4D-PCMRI was used to measure cerebral BFR in 38 patients with symptomatic carotid stenosis (≥50%). BFR in the cerebral arteries was assessed in two subgroups based on symptomatic ICA-BFR: reduced ICA-flow (<160 mL/minutes) and preserved ICA-flow (≥160 mL/minutes). BFR laterality was defined as a difference in the paired ipsilateral-contralateral arteries.

STATISTICAL TESTS

Patients were grouped based on ICA-BFR (reduced vs. preserved). Statistical tests (independent sample t-test/paired t-test) were used to compare groups and hemispheres. Significance was determined at P < 0.05.

RESULTS

The degree of stenosis was not significantly different, 80% (95% confidence interval [CI] = 73%-87%) in the reduced ICA-flow vs. 72% (CI = 66%-76%) in the preserved ICA-flow; P = 0.09. In the reduced ICA-flow group, a significantly reduced BFR was found in the ipsilateral middle cerebral artery and anterior cerebral artery (A1), while significantly increased in the contralateral A1. Retrograde BFR was found in the posterior communicating artery and ophthalmic artery. Significant BFR laterality was present in all paired arteries in the reduced ICA-flow group, contrasting the preserved ICA-flow group (P = 0.14-0.93).

DATA CONCLUSIONS

4D-PCMRI revealed compromised cerebral BFR due to carotid stenosis, not possible to detect by solely analyzing the degree of stenosis. In patients with reduced ICA-flow, collaterals were not sufficient to maintain symmetrical BFR distribution to the two hemispheres.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 3.

Quantifying Carotid Stenosis: History, Current Applications, Limitations, and Potential: How Imaging Is Changing the Scenario

Carotid artery stenosis is a major cause of morbidity and mortality. The journey to understanding carotid disease has developed over time and radiology has a pivotal role in diagnosis, risk stratification and therapeutic management. This paper reviews the history of diagnostic imaging in carotid disease, its evolution towards its current applications in the clinical and research fields, and the potential of new technologies to aid clinicians in identifying the disease and tailoring medical and surgical treatment.

Symptomatic and asymptomatic carotid near-occlusions have very similar angiographic appearance on CT-angiography

The aim of this study was to compare the angiographic appearance of symptomatic and asymptomatic carotid near-occlusion. We have found no such previous study. The study hypothesis was that among symptomatic patients with ≥ 50% carotid stenosis, near-occlusion is more common and near-occlusions are more severe than among asymptomatic persons with ≥ 50% carotid stenosis. We reassessed consecutive CTAs from 4042 persons, 645 had ≥ 50% carotid stenosis, and 385 (60%) symptomatic. Near-occlusion was similarly common in symptomatic (105, 27%) and asymptomatic (56, 24%) cases. Among near-occlusions, the angiographic appearance was very similar between symptomatic and asymptomatic cases: mean stenosis lumen diameter (0.7 mm), distal ICA diameter (2.1 mm), and ECA ratio (0.79) were the same in both groups. Mean ICA ratio (0.46 and 0.48) and share of full collapse was very similar (45% and 42%). These findings add to the pathophysiological understanding of carotid near-occlusion.

Comparison of 30-Day Outcomes after Carotid Artery Stenting in Patients with Near-Occlusion and Severe Stenosis: A Propensity Score Matching Analysis

BACKGROUND AND PURPOSE

Carotid artery near-occlusion is a type of severe stenosis with complete or partial distal luminal collapse and intracranial collaterals. This study aimed to compare 30-day outcomes and 10-year survival in patients undergoing carotid artery stenting for near-occlusion with a control group of patients with severe stenosis.

MATERIALS AND METHODS

We used data from a registry of 639 patients who underwent 789 carotid artery stenting procedures between 2005 and 2021. The primary end point was any stroke or death within 30 days after carotid artery stenting. Patients were matched using propensity scores based on 6 variables.

RESULTS

Propensity score matching yielded 84 subjects in the near-occlusion group matched with 168 subjects in the control group. In the matched cohort, the primary end point occurred in 7 (8.3%) and 11 (6.6%) patients in the near-occlusion and control groups, respectively (P = .611). In the unmatched cohort, the primary end point occurred in 7 (8.3%) and 19 (4.1%) patients (P = .101). Survival in the near-occlusion group versus the control group in the matched cohort at 5 and 10 years was 69.8% (95% CI, 58.0%-78.8%) versus 77.3% (95% CI, 70.0%-83.1%) and 53.3% (95% CI, 39.9%-65.0%) versus 53.3% (95% CI, 44.5%-61.4%) (log-rank, P = .798).

CONCLUSIONS

Carotid stent placement in patients with ICA near-occlusion was not associated with an increased 30-day risk of stroke or death compared with severe stenosis. Survival up to 10 years after carotid artery stenting was similar in both groups.

Carotid Artery Stenting for Near Occlusion with Full Collapse

OBJECTIVE

Carotid near occlusions show a lower risk of stroke than other types of severe stenosis. However, emerging evidence suggests that near occlusion with full collapse differs from that without full collapse. The results of treatment with carotid artery stenting for near occlusion with full collapse are presented.

METHODS

Between March 2007 and December 2020, 18 of 477 carotid artery stenting procedures were performed in patients with near occlusion with full collapse (3.8%). A total of 17 men and one woman with a mean age of 76.1 years were included. Eleven patients (61%) were symptomatic. The technical success rate, incidence of symptomatic stroke within 30 days, new ipsilateral ischemic lesions on diffusion tensor imaging within 48 hours after carotid artery stenting, and follow-up results (ipsilateral stroke rate and restenosis rate) were retrospectively assessed.

RESULTS

The technical success rate was 100%. All carotid artery stenting procedures were performed using embolic protection devices. No symptomatic stroke occurred within 30 days. New ipsilateral ischemic lesions on magnetic resonance imaging were observed in 16.7% (3/18) of patients. Asymptomatic minor cerebral hemorrhage occurred in 2 patients (11.1%) with cerebral hyperperfusion syndrome. The median follow-up period was 77 months. Asymptomatic restenosis of 50% occurred in one patient (5.5%), and asymptomatic occlusion occurred in one patient (5.5%). During follow-up, no patients experienced ipsilateral stroke. Three patients (16.7%) died from nonneurological causes.

CONCLUSIONS

Carotid artery stenting for near occlusion with full collapse seems to be a feasible and safe procedure that can be performed by an experienced neuro-interventional team.

Pendulum Movement of Contrast Agent Indicating to-and-fro Blood Flow Stasis in a Patient with Carotid Near-Occlusion

In the present case, we directly visualized the pendulum movement of the contrast agent downstream of a carotid near-occlusion during digital subtraction angiography, suggesting the existence of "to-and-fro" stagnant flow created by the significant flow reduction and high back pressure from visible ophthalmic collaterals with blood stagnation distal to the stenosis. The pendular movement phenomenon represents a stagnation of blood that could be associated with an increased risk of thrombus formation and subsequent embolization to more distal arterial territories. This case may partially explain not only the embolic mechanism for stroke in carotid near-occlusion but the recent observation that collateral circulation through the ipsilateral ophthalmic artery is associated independently with an increased risk of the progression of carotid near-occlusion to complete occlusion.

Near-Occlusion is a Common Variant of Carotid Stenosis: Study and Systematic Review

BACKGROUND

Symptomatic carotid near-occlusion is often described as rare. Recent studies have shown that near-occlusions are overlooked, especially near-occlusion without full collapse (with a small but normal-appearing distal internal carotid artery).

OBJECTIVE

To assess the prevalence of near-occlusion among symptomatic ≥50% carotid stenosis, incidence of symptomatic near-occlusion, and review the literature.

METHODS

Prospective controlled single-center cross-sectional study. Consecutive cases with symptomatic ≥50% carotid stenosis were examined with computed tomography angiography (CTA). The CTAs were assessed for near-occlusion by two observers. A systematic literature review was performed with emphasis on how study design affects prevalence estimate.

RESULTS

Totally, 186 patients with symptomatic ≥50% carotid stenosis were included, 34% (n = 63, 95% CI 27, 41) had near-occlusion. The incidence of symptomatic near-occlusion was 3.4 (95% CI 2.5, 4.2) per 100,000 person-years. Inter-rater κ was 0.71. The average prevalence of near-occlusion among symptomatic ≥50% carotid stenosis was higher in studies with good design (30%, range 27%-34%) than studies without good design (9%, range 2%-10%).

CONCLUSIONS

Near-occlusion is common variant of symptomatic ≥50% carotid stenosis, both in the current study and in all previous studies of good design. Studies that suggest that near-occlusion is rare have had methodological issues.

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

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.

Diagnosing Carotid Near-Occlusion with Phase-Contrast MRI

Carotid near-occlusion is a frequently overlooked diagnosis when CTA examinations are assessed in routine practice. To evaluate the potential value of phase-contrast MR imaging in identifying near-occlusion, we examined 9 carotid near-occlusions and 20 cases of conventional ≥50% carotid stenosis (mean stenosis degree, 65%) with phase-contrast MR imaging. Mean ICA flow was lower in near-occlusions (52 mL/min) than in conventional ≥50% stenosis (198 mL/min, P < .001). ICA flow of ≤110 mL/min was 100% sensitive and specific for near-occlusion. Phase-contrast MR imaging is a promising tool for diagnosing carotid near-occlusion.

Near-occlusion is difficult to diagnose with common carotid ultrasound methods

Purpose

To assess the sensitivity and specificity of common carotid ultrasound method for carotid near-occlusion diagnosis.

Methods

Five hundred forty-eight patients examined with both ultrasound and CTA within 30 days of each other were analyzed. CTA graded by near-occlusion experts was used as reference standard. Low flow velocity, unusual findings, and commonly used flow velocity parameters were analyzed.

Results

One hundred three near-occlusions, 272 conventional ≥50% stenosis, 162 <50% stenosis, and 11 occlusions were included. Carotid ultrasound was 22% (95%CI 14–30%; 23/103) sensitive and 99% (95%CI 99–100%; 442/445) specific for near-occlusion diagnosis. Near-occlusions overlooked on ultrasound were found misdiagnosed as occlusions (n = 13, 13%), conventional ≥50% stenosis (n = 65, 63%) and < 50% stenosis (n = 2, 2%). No velocity parameter or combination of parameters could identify the 65 near-occlusions mistaken for conventional ≥50% stenoses with >75% sensitivity and specificity.

Conclusion

Near-occlusion is difficult to diagnose with commonly used carotid ultrasound methods. Improved carotid ultrasound methods are needed if ultrasound is to retain its position as sole preoperative modality.

[Ct-angiography in assessment of critical occlusive carotid artery disease]

BACKGROUND

Occlusive carotid artery disease is still one of the major causes of ischemic stroke in the world. Progression of severe carotid stenosis may lead to critical stenosis and vascular occlusion. Nevertheless, there is still no pure definition of the concept of critical occlusive carotid artery disease.

OBJECTIVE

To define the role of CT-angiography in assessment of critical occlusive carotid artery disease.

MATERIAL AND METHODS

We analyzed data of 405 patients who underwent preoperative precise assessment of carotid arteries and subsequent surgical treatment for the period from 2016 to 2019. Contrast-enhanced CT-angiography (Philips Ict scanner, 256 slices) was made after previous ultrasound. Contrast agent injection rate was 4-5 ml/sec. CT angiography data were assessed according to a specialized protocol.

RESULTS

Critical occlusive carotid artery disease was observed in 128 (31.6%) cases including critical stenosis (24.94%), near-occlusion (5.92%) and local occlusion (0.74%). Critical stenosis was characterized by local narrowing ≥90% and normal diameter of distal arterial segment. In case of near-occlusion, local critical stenosis was accompanied by narrowing of distal arterial segment. In case of local occlusion, distal collateral supply of internal carotid artery occurred through atypically originating ascending pharyngeal artery. Patients with near-occlusion and local occlusion of internal carotid artery had no signs of ICA hypoplasia and intracranial stenoses. All elements of circle of Willis were observed in 70% of patients.

CONCLUSION

State of distal segment of internal carotid artery can be considered as a differential diagnostic criterion for critical occlusive carotid disease variants. CT-angiography provides all necessary data and can be recommended for precise preoperative assessment.

Ultrasonographic and hemodynamic characteristics of patients with symptomatic carotid near-occlusion: results from a multicenter registry study

PURPOSE

The ultrasonographic and hemodynamic features of patients with carotid near-occlusion (CNO) are still not well known. Our aim was to describe the ultrasonographic and hemodynamic characteristics of a cohort of patients with CNO.

METHODS

A prospective, observational, nationwide, and multicenter study was conducted from January/2010 to May/2016. Patients with digital subtraction angiography (DSA)-confirmed CNO were included. We collected information on clinical and demographic characteristics, carotid and transcranial ultrasonography and DSA findings, presence of full-collapse, collateral circulation, and cerebrovascular reactivity (CVR).

RESULTS

One hundred thirty-five patients were analyzed. Ultrasonographic and DSA diagnosis of CNO were concordant in only 44%. This disagreement was related to the presence/absence of full-collapse: 45% of patients with CNO with full-collapse were classified as a complete carotid occlusion, and 40% with a CNO without full-collapse were interpreted as severe stenosis (p < 0.001). Mean velocities (mV) and pulsatility indexes (PIs) were significantly lower in the ipsilateral middle cerebral artery compared with the contralateral (43 cm/s vs 58 cm/s, p < 0.001; 0.80 vs 1.00, p < 0.001). Collateral circulation was identified in 92% of patients, with the anterior communicating artery (73%) being the most frequent. CVR was decreased or exhausted in 66% of cases and was more frequent in patients with a poor or absent collateral network compared with patients with ≥ 2 collateral arteries (82% vs 56%, p = 0.051).

CONCLUSION

The accuracy of carotid ultrasonography in the diagnosis of CNO seems to be limited, with significant discrepancies with DSA. Decreased ipsilateral mV, PI, and CVR suggest a hemodynamic compromise in patients with CNO.

Carotid near-occlusion is often overlooked when CT angiography is assessed in routine practice

Objective

Assess the sensitivity and specificity of computed tomography angiography (CTA) for carotid near-occlusion diagnosis interpreted in clinical practice against expert assessment.

Methods

CTAs were graded by two expert interpreters for near-occlusion. Findings were compared with clinical reports in 383 consecutive cases with symptomatic ≥ 50% carotid stenosis. In addition, 14 selected CTA exams (8 near-occlusions and 6 controls) were analyzed in a national effort by 13 radiologists experienced with carotid CTA.

Results

In clinical practice, imaging reports were 20% (95% CI 12–28%) sensitive for near-occlusion, ranging 0–58% between different radiologists; specificity was 99%. Among the 13 radiologists reviewing the same 8 near-occlusions, the average sensitivity was 8%, ranging 0–75%; specificity was 100%.

Conclusions

Carotid near-occlusion is systematically under-reported in clinical routine practice, caused by limited application of grading criteria when assessing CTA.

Key Points

• Carotid near-occlusion is severe stenosis with distal artery collapse; this collapse is often subtle.

• A fifth of near-occlusions were detected in routine practice. Many readers mistake near-occlusion for stenosis without distal artery collapse, either by not actively searching for subtle collapses or by not interpreting the collapse correctly when noticed.

• On the other hand, the novice diagnostician should be cautioned to not over-diagnose near-occlusion; other causes of extracranial ICA asymmetry also exist such as distal disease and Circle of Willis anatomical variants.

Atherosclerotic ICA stenosis coinciding with ICA asymmetry associated with Circle of Willis variations can mimic near-occlusion

Differentiating carotid near-occlusion (tight atherosclerotic stenosis causing distal artery size reduction) from conventional stenosis is the first step when grading carotid stenoses with NASCET method. The internal carotid artery (ICA) can be asymmetrically associated with Circle of Willis variations. When such ICA asymmetry coincides with stenosis, it may mimic near-occlusion. We studied ICA anatomical variant prevalence in 4042 consecutive CTA exams from all indications, 53 excluded due to carotid occlusion, 814 with any ≥ 50% steno-occlusive disease intra- or extracranially, 3228 without. Of the 3989 included cases, 568 (14%) had ICA asymmetry, of which 335 (59%) were from associated with Circle of Willis variations. Of 3228 patients without ≥ 50% stenosis or other steno-occlusive disease intra- and extracranially; 257 (8.0%) demonstrated ICA asymmetry associated with Circle of Willis variations, equally common among sexes and age unrelated and most frequently attributed to an ipsilateral A1 hypoplasia/aplasia, less often attributed to large contralateral posterior communicating artery. As ICA asymmetry associated with Circle of Willis variations are common, caution should be exercised diagnosing near-occlusion on asymmetry alone.

Symptomatic carotid near-occlusion causes a high risk of recurrent ipsilateral ischemic stroke

Objective

To assess the risk of recurrent ipsilateral ischemic stroke in patients with symptomatic near-occlusion with and without full collapse.

Methods

Included were consecutive patients eligible for revascularization, grouped into symptomatic conventional ≥ 50% carotid stenosis (n = 266), near-occlusion without full collapse (n = 57) and near-occlusion with full collapse (n = 42). The risk of preoperative recurrent ipsilateral ischemic stroke was analyzed, or, for cases not revascularized within 90 days, 90-day risk was analyzed.

Results

The risk of a preoperative recurrent ipsilateral ischemic stroke or ipsilateral retinal artery occlusion was 15% (95% CI 9–20%) for conventional ≥ 50% stenosis, 22% (95% CI 6–38%) among near-occlusion without full collapse and 30% (95% CI 16–44%) among near-occlusion with full collapse (p = 0.01, log rank test). In multivariate analysis, near-occlusion with full collapse had a higher risk of recurrent ipsilateral ischemic stroke (adjusted HR 2.6, 95% CI 1.3–5.3) and near-occlusion without full collapse tended to have a higher risk (adjusted HR 2.0, 95% CI 0.9–4.5) than conventional ≥ 50% stenosis. Only 24% of near-occlusion with full collapse underwent revascularization, common causes for abstaining were misdiagnosis as occlusion (31%), deemed surgically unfeasible (21%) and low perceived benefit (10%).

Conclusions

Symptomatic carotid near-occlusion has a high short-term risk of recurrent ipsilateral ischemic stroke, especially near-occlusion with full collapse.

Carotid near-occlusion can be identified with ultrasound by low flow velocity distal to the stenosis

BACKGROUND

Most carotid near-occlusions are indistinguishable from conventional ≥ 50% stenosis on ultrasound, demonstrating high peak systolic velocity (PSV) in the stenosis.

PURPOSE

To study whether the velocity distal to the stenosis can separate high PSV near-occlusion from conventional ≥ 50% stenosis.

MATERIAL AND METHODS

We included patients with ≥ 50% carotid stenosis with high PSV (≥125 cm/s), examined with both computed tomography angiography (CTA) and ultrasound within 30 days, and a distal velocity measurement was performed. Based on CTA, cases were divided into three groups: conventional stenosis; near-occlusion without full collapse (NwoC; normal-appearing albeit small distal artery); and near-occlusion with full collapse (NwC; threadlike distal artery). Distal Doppler ultrasound flow velocities were compared between these groups.

RESULTS

Sixty patients were included: 33 patients with conventional stenosis; 20 patients with NwoC; and seven patients with NwC. Mean distal PSV was 93, 63, and 21 cm/s ( P < 0.001) and mean distal end-diastolic velocity was 30, 24, and 5 cm/s ( P < 0.001), respectively. A distal PSV < 50 cm/s was 63% sensitive and 94% specific for separating both types of near-occlusion from conventional stenosis.

CONCLUSION

In high PSV carotid stenoses, the distal velocity was lower in near-occlusions than conventional carotid stenosis. Distal velocities warrant further investigation in diagnostic studies.

Carotid endarterectomy in patients with recurrent symptoms associated with an ipsilateral carotid artery near occlusion with full collapse

OBJECTIVE

Near occlusion (NO) of the internal carotid artery (ICA) with full collapse (NOFC) is a rare condition, with a prevalence of around 1%. Guidelines on carotid stenosis recommend a conservative treatment in patients with a single-event ipsilateral to a NOFC, but the optimal treatment for patients with recurrent symptoms associated with NOFC remains uncertain. We describe a consecutive series of patients with recurrent symptoms associated with NOFC (RSNOFC) who underwent carotid endarterectomy (CEA).

METHODS

From 2008 to 2017, 17 consecutive patients with RSNOFC were treated according to our standardized multidisciplinary work-up and protocol and included for this single-center cohort study. NO was defined according to the angiographic North American Symptomatic Carotid Endarterectomy Trial criteria. Only patients with NOFC were included in this study.

RESULTS

Standard longitudinal CEA was performed in 15 patients, whereas in 2 patients the ICA was ligated with concomitant endarterectomy of the ECA. Within 30 postoperative days, one patient died from a hemorrhagic infarction. During follow-up (median 23 months) one patient died of unknown cause 90 days after CEA. No TIA, stroke, myocardial infarction or re-stenosis occurred in the remaining patients.

CONCLUSION

In patients with RSNOFC, CEA may be considered a potential treatment option. Although procedural risks in this small subgroup may be higher as compared to patients with low-to-moderate risk anatomy, this risk may outbalance the natural course.

Carotid near-occlusion frequently has high peak systolic velocity on Doppler ultrasound

PURPOSE

Carotid near-occlusion is a tight atherosclerotic stenosis of the internal carotid artery (ICA) resulting in decrease in diameter of the vessel lumen distal to the stenosis. Near-occlusions can be classified as with or without full collapse, and may have high peak systolic velocity (PSV) across the stenosis, mimicking conventional > 50% carotid artery stenosis. We aimed to determine how frequently near-occlusions have high PSV in the stenosis and determine how accurately carotid Doppler ultrasound can distinguish high-velocity near-occlusion from conventional stenosis.

METHODS

Included patients had near-occlusion or conventional stenosis with carotid ultrasound and CT angiogram (CTA) performed within 30 days of each other. CTA examinations were analyzed by two blinded expert readers. Velocities in the internal and common carotid arteries were recorded. Mean velocity, pulsatility index, and ratios were calculated, giving 12 Doppler parameters for analysis.

RESULTS

Of 136 patients, 82 had conventional stenosis and 54 had near-occlusion on CTA. Of near-occlusions, 40 (74%) had high PSV (≥ 125 cm/s) across the stenosis. Ten Doppler parameters significantly differed between conventional stenosis and high-velocity near-occlusion groups. However, no parameter was highly sensitive and specific to separate the groups.

CONCLUSION

Near-occlusions frequently have high PSV across the stenosis, particularly those without full collapse. Carotid Doppler ultrasound does not seem able to distinguish conventional stenosis from high-velocity near-occlusion. These findings question the use of ultrasound alone for preoperative imaging evaluation.

Early risk of recurrent stroke in patients with symptomatic carotid near-occlusion: Results from CAOS, a multicenter registry study

Background

The risk of recurrent stroke among patients with symptomatic carotid near-occlusion is not well established, and management of the condition remains controversial. Symptomatic carotid near-occlusion with full collapse has been identified as a strong predictor of early recurrence. We aimed to analyze the 90-day risk of recurrent ipsilateral ischemic stroke in medically treated patients with symptomatic carotid near-occlusion.

Methods

We performed a multicenter, nationwide, prospective study from January 2010 to May 2016. Patients with angiography-confirmed symptomatic carotid near-occlusion were included. The primary endpoint was ipsilateral ischemic stroke or transient ischemic attack (TIA) within 90 days after the presenting event. For this analysis, patients who underwent revascularization within 90 days after stroke were excluded.

Results

The study population comprised 141 patients from 17 Spanish centers; 83 patients were treated medically. Primary endpoint occurred in eight patients, resulting in a cumulative rate of 10.6% (95% CI, 3.7–17.5). Previous history of stroke or transient ischemic attack was identified as an independent predictor for recurrence in the multivariate Cox regression analysis (HR, 4.37 [95% CI, 1.05–18.18]; p = 0.043), while the presence of full collapse was not associated with an increased risk (HR, 0.81 [95% CI, 0.17–3.92]; p = 0.793). The risk of recurrence was also not affected by the presence of significant stenosis or occlusion of the contralateral carotid artery, or by the collateral circulation.

Conclusions

Patients with symptomatic carotid near-occlusion seem to have an increased risk of early ipsilateral recurrent stroke. Our results contrast with the low risk of symptomatic carotid near-occlusion reported to date. Full collapse did not increase the risk of recurrent stroke in our study.

Endovascular Treatment for Near Occlusion of the Internal Carotid Artery : 30-Day Outcome and Long-Term Follow-Up

BACKGROUND

The treatment strategy and the correct incidence of near occlusion (NO) of the internal carotid artery (ICA) is still controversial. In routine radiological imaging NO can easily be misdiagnosed as complete occlusion and there is no consensus on the standard treatment strategy.

PURPOSE

To present our perioperative and long-term follow-up results of ICA NO patients treated with carotid artery stenting (CAS).

MATERIAL AND METHODS

Between 2004-2014 a total of 182 patients with ICA NO were evaluated for CAS. The study included 132 male (72.5 %) and 50 female (27.5 %) patients with a mean age of 70.2 years. Patients underwent a clinical neurological evaluation and radiological imaging of the carotid arteries before the CAS procedure. Of the patients 80 (44 %) were asymptomatic. The median clinical and carotid Doppler ultrasound (DUS) follow-up period was 64 months (range 18-124 months).

RESULTS

In 182 patients CAS were performed, 4 patients (2.2 %) developed minor stroke, 2 patients (1.1 %) developed myocardial infarction but no major stroke or death occurred in the following 30-day period. Asymptomatic restenosis was detected in seven patients (3.8 %) in the follow-up period.

CONCLUSION

With sufficient neurological evaluation during pretreatment and posttreatment periods and when the procedure is performed with technologically developed products by an experienced interventional team, CAS is beneficial in patients with ICA NO.