Carotid plaque characterization by virtual histology intravascular ultrasound related to the timing of carotid intervention

Clinical Utility of Intravascular Ultrasound (IVUS) in Carotid Artery Interventions: A Systematic Review and Meta-analysis

BACKGROUND

Carotid plaque morphology plays an important role in determining outcome of carotid artery stenting (CAS). Intravascular ultrasound (IVUS) and its extension VH (Virtual Histology)-IVUS evaluate plaque characteristics in real time and guide decision making during stenting. To date, there is no consensus about indications of IVUS and its validated methods. This systematic review and meta-analysis aims to evaluate the clinical utility of IVUS in carotid artery interventions (CAS) and develop a future consensus for research and practice parameters.

METHODS

A systematic review and meta-analysis was performed of the English literature articles published till February 2021. Studies reporting on IVUS parameters and findings and also its performance compared with other imaging modalities were included in review. Pooled prevalence with 95% confidence intervals (CI) was calculated. The statistical analysis was conducted in R version 3.6.2.

RESULTS

A total of 2015 patients from 29 studies were included. Proportional meta-analysis was performed on 1566 patients from 11 studies. In 9 studies, stroke/transient ischemic attack (TIA) had a pooled prevalence of 4% (95% CI 3%-5%) while asymptomatic stroke had a pooled prevalence of 46% (95% CI 31%-62%) in 4 studies following IVUS. Two studies reported that IVUS detected more plaque protrusion compared with angiography (n=33/396 vs 11/396). IVUS led to stent type or size change in 8 of 48 cases which were missed on angiography in 3 other studies. Concordance between VH-IVUS and true histology was good at 80% to 85% reported in 2 studies.

CONCLUSIONS

This systematic review and meta-analysis showed, though IVUS fared better to computed tomography (CT)/magnetic resonance (MR) angiography for better stent selection during CAS, with low to moderate risk of bias in the studies included. However, large scale, preferably randomized controlled studies are needed to predict its role in determining clinical outcome.

Thirty-Day Outcome of Carotid Artery Stenting in Elderly Patients: A Single-Center Experience

BACKGROUND

The safety of carotid artery stenting (CAS) in elderly patients is controversial. The aims of this study were to evaluate 30-day outcomes after CAS in elderly patients (≥70 years old) and to investigate risk factors for postoperative incidence of major adverse clinical events (MACE) to improve CAS safety based on clinical evidence in this specific subgroup of patients.

METHODS

The data set included patients who underwent CAS between 2001 and 2017 at Xuanwu Hospital, Capital Medical University. The primary outcome variable was 30-day postoperative incidence of the following MACE: death, myocardial infarction, and ipsilateral stroke. Univariate and multivariate analyses were performed to identify high-risk patients and procedural characteristics associated with MACE.

RESULTS

A total of 1029 elderly patients who underwent CAS for carotid artery stenosis were identified and analyzed. The incidence of postoperative MACE was 3.01% (n = 31 cases [5 deaths, 24 strokes, and 2 myocardial infarctions]). After multivariate analysis, independent predictors of MACE included a family history of stroke (odds ratio [OR] = 3.817; 95% confidence interval [CI], 1.227-11.876; P = 0.021), symptomatic status (OR = 2.650; 95% CI, 1.210-5.806; P = 0.015), and modified Rankin Scale score ≥3 (OR = 4.594; 95% CI, 1.708-12.352; P = 0.003). Hyperlipidemia was not an independent risk factor (OR = 1.597; 95% CI, 0.745-3.425; P = 0.229).

CONCLUSIONS

At our center, CAS was safely performed in elderly patients. A family history of stroke, symptomatic status, and modified Rankin Scale score ≥3 indicating a neurologic deficit increased the risk of 30-day postoperative MACE.

Intravascular ultrasound-guided internal carotid artery stenting

AIM

The study was aimed at demonstrating efficacy and feasibility of intravascular ultrasound during internal carotid artery stenting for assessment of atheromatous plaque protrusion through a stent.

PATIENTS AND METHODS

Over the period from October to December 2018, the specialists of our Centre performed a total of 90 internal carotid artery stenting procedures in 83 patients (of these, 7 patients underwent bilateral staged stenting of both internal carotid arteries) using intravascular ultrasound in order to assess intraoperative protrusion of an atherosclerotic plaque through the implanted stent. The patients' age varied from 42 to 87 (mean 68.6±6.9) years. Symptomatic lesions of internal carotid arteries were revealed in 14 (16.9%) operated patients and asymptomatic lesions in 69 (83.1%). The degree of stenosis varied from 60% to 90% according to the findings of preliminary duplex ultrasonography and was subsequently confirmed by the results of multislice computed tomography or selective angiography. The assessment of the patients' neurological status, as well as duplex ultrasonography of brachiocephalic arteries were performed at a scheduled follow-up visit on day 30 after discharge from hospital.

RESULTS

The technical success of stenting was achieved in 100% of patients. According to the findings of intravascular ultrasound, plaque protrusion was observed in eight (8.8%) stented patients. Among them, six (6.6%) were free from angiographic signs of protrusion and only two (2.2%) had apparent angiographic signs of protrusion. During the early postoperative period, transient ischaemic attack was identified in four (4.4%) cases. One (1.1%) patient was found to develop ST-segment elevation acute myocardial infarction 24 hours after internal carotid artery stenting, followed by large hemispheric stroke on the side of stenting revealed on postoperative day 3. Nine (10%) patients according to the findings of intravascular ultrasound were diagnosed as having incomplete stent apposition after postdilatation, with the absence of such signs on angiography.

CONCLUSION

Intravascular ultrasound during carotid stenting provides a more accurate assessment of such an event as atherosclerotic plaque protrusion through a stent's cells. At the same time, IVUS-guided assessment of the intraoperative outcome may prevent the risk for the development of stroke in the early postoperative period. Besides, intravascular ultrasound allows a more detailed assessment of stent apposition and the degree of stent expansion in order to optimize and improve the remote results of the operation.

The Growing Field of Imaging of Atherosclerosis in Peripheral Arteries

In the past decades, peripheral arteries have represented a model for the comprehension of atherosclerosis as well as for the development of new diagnostic imaging modalities and therapeutic strategies. Peripheral arteries may represent a window to study atherosclerosis. Pathology has prominently contributed to move the clinical and research attention from the arterial lumen stenosis and angiography to morphological and functional imaging techniques. Evidence from large and prospective cohort or randomized controlled studies is still modest. Nevertheless, several emerging imaging investigations represent a potential tool for a comprehensive "in vivo" evaluation of the entire natural history of peripheral atherosclerosis. This constitutes a demanding assignment, as it would be desirable to obtain both single-lesion focused and extensive arterial system views to achieve the most accurate prognostic information. Our narrative review rests upon the fundamental pathological evidence, summarizing the rapidly growing field of imaging of atherosclerosis in peripheral arteries and presenting a selection of both currently available and emerging imaging techniques.

Safety and Feasibility of Carotid Artery Stenting with Dual-Echo Technique to Minimize Iodinated Contrast Dose

BACKGROUND

The aim of this study was to evaluate the safety and feasibility of carotid artery stenting (CAS) employing dual-ultrasound technique and administering a minimal contrast agent in patients with renal insufficiency.

METHODS

Between September 2009 and July 2013, 63 consecutive patients underwent CAS at our institution: dual-echo carotid artery stenting (DECAS) in 7 patients with renal insufficiency and standard carotid artery stenting (STCAS) in the remaining 56 patients. Periprocedural adverse events and outcomes were compared between the 2 groups.

RESULTS

Technical success was achieved in all cases. The 3 procedure-related complications were 1 case of transient hemiparesis in the DECAS group and 1 transient and 1 permanent case of hemiparesis in the STCAS group. The rate of positive diffusion-weighted-imaging lesions did not differ significantly between the 2 groups (28.6% versus 12.5%, P = .26). A significantly smaller volume of contrast was used in DECAS (15 versus 163 mL, P < .01). The change in creatinine level remained stable after CAS and did not differ between the 2 groups (.02 versus .03 mg/dL, P = .96).

CONCLUSIONS

DECAS is safe and feasible for patients with pre-existing renal insufficiency and can provide an alternative for patients with carotid stenosis and renal insufficiency.

A Review on Carotid Ultrasound Atherosclerotic Tissue Characterization and Stroke Risk Stratification in Machine Learning Framework

Cardiovascular diseases (including stroke and heart attack) are identified as the leading cause of death in today's world. However, very little is understood about the arterial mechanics of plaque buildup, arterial fibrous cap rupture, and the role of abnormalities of the vasa vasorum. Recently, ultrasonic echogenicity characteristics and morphological characterization of carotid plaque types have been shown to have clinical utility in classification of stroke risks. Furthermore, this characterization supports aggressive and intensive medical therapy as well as procedures, including endarterectomy and stenting. This is the first state-of-the-art review to provide a comprehensive understanding of the field of ultrasonic vascular morphology tissue characterization. This paper presents fundamental and advanced ultrasonic tissue characterization and feature extraction methods for analyzing plaque. Additionally, the paper shows how the risk stratification is achieved using machine learning paradigms. More advanced methods need to be developed which can segment the carotid artery walls into multiple regions such as the bulb region and areas both proximal and distal to the bulb. Furthermore, multimodality imaging is needed for validation of such advanced methods for stroke and cardiovascular risk stratification.

Early carotid artery stenting for symptomatic carotid artery stenosis

BACKGROUND

The aim of present study was to assess safety and efficacy of early carotid artery stent (CAS) in patients with symptomatic carotid artery stenosis compared with delayed CAS.

METHODS

This retrospective study was approved by the institutional review board, and the requirement to obtain written informed consent was waived. Outcomes of 206 patients with symptomatic carotid stenosis who were treated by CAS were analyzed. According to CAS timing from last symptom, patients were divided into early (within 2 weeks, 74 [35.0 %]) and delayed (after 2 weeks, 112 [64.1 %]) group by CAS timing from the last symptom. Procedural complication and early (≤30 days of CAS) event (ipsilateral stroke or any death) for safety, and late (31 days to 1 year of CAS) event for efficacy of CAS preventing further stroke were evaluated. The two groups were compared using Cox proportional hazard analysis.

RESULTS

No difference was found in procedural complication between the groups (early 2 [2.7 %] vs. delayed group 7 [5.3 %], hazard ratio [HR] 0.61, 95 % confidence interval [CI] 0.123-2.979, p = 0.537). In the early group, however, early event developed more frequently than in the late group (9 [12.2 %] vs. 1 [0.8 %], HR 16.05, 95 % CI 1.991-129.438, p = 0.009). The late event rate showed no difference between the two groups (4 [5.4 %] vs. 4 [3.0 %], HR 2.09, 95 % CI 0.484-8.989, p = 0.324).

CONCLUSIONS

Early CAS is not safe during periprocedural period, compared with late CAS. In CAS for symptomatic carotid stenosis, delayed CAS should be considered.

Utilization of Intravascular Ultrasound during Carotid Artery Stenting

For patients at high risk for surgery, carotid artery stenting (CAS) is a viable alternative to help reduce risk of stroke for patients with high-grade carotid artery stenosis; however, a higher incidence of perioperative stroke has been observed in patients undergoing stenting compared to those undergoing open surgery. Intravascular ultrasound (IVUS) is commonly used during coronary artery procedures to help evaluate lesions and to guide stent placement. Multiple groups have sought to determine whether IVUS could also be used during CAS. While IVUS has been shown to be both feasible and safe during CAS, there is limited evidence that demonstrates direct improvement in procedural outcomes. Further studies focusing on clinical outcomes should be conducted in order to justify routine use of this technology during CAS.

Intravascular ultrasound as a clinical adjunct for carotid plaque characterization

OBJECTIVE

Virtual histology intravascular ultrasound (VH IVUS) is valuable for estimating minimal lumen diameter and plaque characterization. The clinical use of IVUS in carotid intervention is not well characterized. We aim to evaluate the role of IVUS in carotid plaque characterization and determine whether it could be predictive of procedure-related microemboli.

METHODS

From July 2010, patients with severe carotid stenosis who underwent elective carotid stenting procedures were prospectively enrolled. IVUS evaluation was performed before stent placement. Patient demographics, comorbidities, and preoperative images were recorded. Comparison of pre- and postoperative diffusion-weighted magnetic resonance images was used to identify the number of procedure-related microemboli. IVUS-derived minimal lumen diameter and vessel wall plaque characteristics were collected. Univariate and multivariate logistic regressions were used to search for associations between IVUS-derived VH data and incidence of microemboli.

RESULTS

A total of 38 high-risk patients receiving carotid stenting were enrolled. Among them, 25 patients had type I aortic arches and 17 of the patients were symptomatic (preoperative stroke or transient ischemic attack). VH IVUS data did not show strong associations with microemboli, however, a trend was found between the area of fibrous tissue and median or more incidence of microemboli (P = .099). IVUS-defined vessel diameter maximum was associated with median or more incidence of microemboli (P = .042). In addition, median or more incidence of microemboli showed trends with proximal common carotid artery calcification (P = .056) and with being over the age of 80 (P = .06). Contralateral carotid occlusion or high-grade stenosis was associated with postoperative contralateral microemboli (P = .036).

CONCLUSIONS

We demonstrate that periprocedural carotid IVUS is clinically feasible. VH IVUS may be helpful in better understanding plaque morphology and determining optimal stent placement. However, its use in predicting microembolization remains limited.