Editor's Choice - Risk of Stroke before Revascularisation in Patients with Symptomatic Carotid Stenosis: A Pooled Analysis of Randomised Controlled Trials

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.

Risk of new cerebral ischemic events in patients with symptomatic internal carotid artery stenosis while awaiting carotid stent placement

BACKGROUND AND PURPOSE

Although there is an emphasis on performing carotid artery stent (CAS) placement within 2 weeks after index event of transient ischemic attack (TIA) or minor stroke in patients with significant extracranial internal carotid artery (ICA) stenosis, the risks and characteristics of recurrent cerebral ischemic event while waiting for CAS placement are not well defined.

METHOD

We analyzed patients admitted to our institution over a 45-month period with symptomatic extracranial ICA stenosis. We identified any new cerebral ischemic events that occurred between index cerebral or retinal ischemic event and CAS placement and categorized them as TIA and minor or major ischemic strokes. We calculated the risk of new ipsilateral cerebral ischemic events between index cerebral or retinal ischemic event and CAS placement.

RESULTS

The mean age of 131 patients analyzed was 67 years (range: 47-94 years; 92 were men), and 94 and 37 patients had 70%-99% and 50%-69% severity of stenosis, respectively. The mean and median time intervals between index cerebral or retinal ischemic event and CAS performance were 28 (standard deviation [SD] 30) and 7 (interquartile range 33) days, respectively. A total of 9 of 131 patients (6.9%, 95% confidence interval 2.5%-11.2%) experienced new cerebral ischemic events over 3637 patient days of observation. The risk of new ipsilateral cerebral ischemic events was 2.5 per 1000 patient days of observation.

CONCLUSION

We estimated the risk of new ipsilateral cerebral ischemic events in patients with ICA stenosis ≥50% in severity while waiting for CAS placement to guide appropriate timing of procedure.

Role of carotid duplex in the assessment of carotid artery restenosis after endarterectomy or stenting

Introduction

Redo carotid endarterectomy (CEA) and carotid stenting (CAS) are often performed when there is evidence of post-procedural restenosis. The incidence of restenosis after carotid reconstruction is not negligible, ranging from 5 to 33%. The diagnosis of significant internal carotid artery (ICA) restenosis is usually based on duplex ultrasound (US) criteria, mostly on peak-systolic flow velocity (PSV). However, there have been no generally accepted duplex US criteria for carotid restenosis after CAS or CEA.

Methods

In this systematic review, the PubMed/ Medline and Scopus databases were screened to find trials that reported duplex US criteria for significant restenosis after CEA and/or CAS. Only those reports were analyzed in which the restenoses were also assessed by CT/MR or digital subtraction angiography as comparators for duplex US.

Results

Fourteen studies met the predetermined search criteria and were included in this review. In most studies, PSV thresholds for significant in-stent ICA restenosis after CAS were higher than those for significant stenosis in non-procedurally treated (native) ICA. Many fewer studies investigated the US criteria for ICA restenosis after CEA. Despite the heterogeneous data, there is a consensus to use higher flow velocity thresholds for assessment of stenosis in stented ICA than in native ICA; however, there have been insufficient data about the flow velocity criteria for significant restenosis after CEA. Although the flow velocity thresholds for restenosis after CAS and CEA seem to be different, the large studies used the same duplex criteria to define restenosis after the two procedures. Moreover, different studies used different flow velocity thresholds to define ICA restenosis, leading to variable restenosis rates.

Discussion

We conclude that (1) further examinations are warranted to determine appropriate duplex US criteria for restenosis after CAS and CEA, (2) single duplex US parameter cannot be used to reliably determine the degree of ICA restenosis, (3) inappropriate US criteria used in large studies may have led to false restenosis rates, and (4) studies are required to determine if there is a benefit from redo carotid artery procedure, such as redo-CEA or redo-CAS, starting with prospective risk stratification studies using current best practice non-invasive care alone.

Long Term Mortality Rate in Patients Treated with Carotid Endarterectomy

OBJECTIVE

Carotid endarterectomy (CEA) is an effective surgical method for stroke prevention in selected patients with carotid stenosis. Few contemporary studies report on the long term mortality rate in CEA treated patients, despite continuous changes in medication, diagnostics, and patient selection. Here, the long term mortality rate is described in a well characterised cohort of asymptomatic and symptomatic CEA patients, sex differences evaluated, and mortality ratio compared with the general population.

METHODS

This was a two centre, non-randomised, observational study evaluating all cause, long term mortality in CEA patients from Stockholm, Sweden between 1998 and 2017. Death and comorbidities were extracted from national registries and medical records. Cox regression was adapted to analyse associations between clinical characteristics and outcome. Sex differences and standardised mortality ratio (SMR, age and sex matched) were studied.

RESULTS

A total of 1 033 patients were followed for 6.6 ± 4.8 years. Of those, 349 patients died during follow up where the overall mortality rate was similar in asymptomatic and symptomatic patients (34.2% vs. 33.7%, p = .89). Symptomatic disease did not influence the mortality risk (adjusted HR 1.14, 95% CI 0.81 - 1.62). Women had lower crude mortality rate than men in the first 10 years (20.8% vs. 27.6%, p = .019). In women, cardiac disease was associated with increased mortality (adjusted HR 3.55, 95% CI 2.18 - 5.79), while in men, lipid lowering medication was protective (adjusted HR 0.61, 95% CI 0.39 - 0.96). Within the first five years after surgery, SMR was increased for all patients (men 1.50, 95% CI 1.21 - 1.86; women 2.41, 95% CI 1.74 - 3.35), as well as in patients < 80 years (SMR 1.46, 95% CI 1.23 - 1.73).

CONCLUSION

Symptomatic and asymptomatic carotid patients have similar long term mortality rates after CEA, but men had worse outcome than women. Sex, age, and time after surgery were shown to influence SMR. These results highlight the need for targeted secondary prevention, to alter the long term adverse effects in CEA patients.

Cost-effectiveness of carotid endarterectomy in symptomatic patients

BACKGROUND

Medical therapy for stroke prevention has improved significantly over the past 30 years. Recent analyses of medically treated cohorts have suggested that early rates of stroke may have reduced, and reports of the safety of carotid surgery have also shown improvements. Since the effectiveness of carotid surgery versus medical therapy was established in the 1990s, there is an urgent need to evaluate whether surgery remains cost-effective in the UK.

METHODS

A decision model was developed to estimate the lifetime costs and utilities of modern medical therapy with and without carotid endarterectomy in patients with symptomatic stenosis from the perspective of the UK National Health Service. The base-case population consisted of adults aged 70 years with 70-99 per cent stenosis. Model data were obtained from clinical studies and wider literature. Univariate and probabilistic sensitivity analyses were carried out.

RESULTS

In the base-case scenario, the 5-year absolute risk reduction with carotid endarterectomy was 5 per cent, and the incremental cost-effectiveness ratio was €12 021 (exchange rate £1 GBP = €1.1125 (Tuesday 1 January 2019)) per quality-adjusted life-year. Surgery was more cost-effective if performed rapidly after presentation. In patients with 50-69 per cent carotid stenosis, surgery appeared less clinically effective. However, there was considerable uncertainty.

CONCLUSION

Surgery may not now be clinically effective and cost-effective in those with moderate carotid stenosis. However, these results are uncertain because of the limited data on modern medical therapy and an RCT may be justified.

Hypertriglyceridemia and Atherosclerotic Carotid Artery Stenosis

Both fasting and non-fasting hypertriglyceridemia have emerged as residual risk factors for atherosclerotic disease. However, it is unclear whether hypertriglyceridemia increases the risks of the progression of carotid artery stenosis. Statins are well known to prevent carotid plaque progression and improve carotid plaque instability. In addition, statin therapy is also known to reduce cerebrovascular events in patients with carotid artery stenosis and to improve clinical outcomes in patients undergoing revascularization procedures. On the other hand, there have been no randomized controlled trials showing that the combination of non-statin lipid-lowering drugs with statins has additional beneficial effects over statin monotherapy to prevent cerebrovascular events and stenosis progression in patients with carotid artery stenosis. In this article, the authors demonstrate the mechanisms of atherosclerosis formation associated with hypertriglyceridemia and the potential role of lipid-lowering drugs on carotid artery stenosis. The authors also review the articles reporting the relationships between hypertriglyceridemia and carotid artery stenosis.

Extra-Cranial Carotid Artery Stenosis: An Objective Analysis of the Available Evidence

Background and Purpose

Carotid stenosis is arterial disease narrowing of the origin of the internal carotid artery (main brain artery). Knowing how to best manage this is imperative because it is common in older people and an important cause of stroke. Inappropriately high expectations have grown regarding the value of carotid artery procedures, such as surgery (endarterectomy) and stenting, for lowering the stroke risk associated with carotid stenosis. Meanwhile, the improving and predominant value of medical intervention (lifestyle coaching and medication) continues to be underappreciated.

Methods and Results

This article aims to be an objective presentation and discussion of the scientific literature critical for decision making when the primary goal is to optimize patient outcome. This compilation follows from many years of author scrutiny to separate fact from fiction. Common sense conclusions are drawn from factual statements backed by original citations. Detailed research methodology is given in cited papers. This article has been written in plain language given the importance of the general public understanding this topic. Issues covered include key terminology and the economic impact of carotid stenosis. There is a summary of the evidence-base regarding the efficacy and safety of procedural and medical (non-invasive) interventions for both asymptomatic and symptomatic patients. Conclusions are drawn with respect to current best management and research priorities. Several "furphies" (misconceptions) are exposed that are commonly used to make carotid stenting and endarterectomy outcomes appear similar. Ongoing randomized trials are mentioned and why they are unlikely to identify a routine practice indication for carotid artery procedures. There is a discussion of relevant worldwide guidelines regarding carotid artery procedures, including how they should be improved. There is an outline of systematic changes that are resulting in better application of the evidence-base.

Conclusion

The cornerstone of stroke prevention is medical intervention given it is non-invasive and protects against all arterial disease complications in all at risk. The "big" question is, does a carotid artery procedure add patient benefit in the modern era and, if so, for whom?

The Weekend Effect in Carotid Endarterectomy for Symptomatic Carotid Stenosis

BackgroundRecent studies report a limited window in which carotid endarterectomy (CEA) provides the greatest benefit for symptomatic carotid stenosis. Given the time-sensitive nature of CEA for symptomatic stenosis, it is important to understand whether patient outcomes are adversely affected by undergoing CEA over the weekend. Currently, it is unclear whether CEA is impacted by the "weekend effect" phenomenon. Methods A multi-institutional database was queried for all patients undergoing CEA for symptomatic carotid artery stenosis from 2015 to 2020 via ICD-9 codes. A total of 288 patients were identified during the study period. Univariate and multivariate analysis were used to compare outcomes based on weekend vs weekday surgery. Results A total of 261 patients (90.6%) underwent weekday CEA, as compared to 27 (9.4%) on the weekend. There were no differences in age, race, gender, or medical comorbidities between groups. Primary surgeon specialty was predominantly vascular surgery (77.0% weekday and 74.1% weekend) followed by neurosurgery (19.9% weekday and 25.9% weekend). Operative time was similar between groups (3.1 (weekday) vs 2.9 hr (weekend), P = .33) as well as estimated blood loss (100 vs 100 mL, P = .54). Hospital length of stay did not differ between groups (P = .69). Combined stroke and 30-day mortality rate was 2.0% on weekdays, compared to 3.7% on weekends (P = .75). On multivariate analysis, weekend surgery was not predictive of postoperative stroke or 30-day mortality (odds ratio .11 [95% CI: -1.57 to 1.85], P = .90). Conclusion In our multi-institutional experience, we did not identify a "weekend effect" in patients undergoing CEA for symptomatic carotid artery stenosis. Surgical revascularization should not be withheld on account of a weekend procedure in similar academic medical centers.

NIHSS score at admission can predict functional outcomes in patients with ischemic stroke undergoing carotid endarterectomy

OBJECTIVE

The aim of present study was to evaluate the prognostic impact of National Institutes of Health Stroke Scale (NIHSS) score in patients undergoing acute CEA, and to assess clinical and morphological factors that could predict worse outcomes.

METHODS

The data of 183 consecutive patients who have undergone CEA after ischemic stroke was analyzed from January 2015 to January 2021. Patients were divided into two groups using the NIHSS cut off point of 4. Functional dependence was assessed on hospital discharge and 90 days after.

RESULTS

In total, 102 patients (55.7%) had a minor stroke (Group A: NIHSS ≤ 4), whereas 81 patients (44.3%) had a moderate-major stroke (Group B: NIHSS > 4). Group A and group B showed significant differences in their intracranial anatomic features: presence of incomplete Circle of Willis (7.8% vs 17.3%; p=.05), volume of Cerebral ischemic lesion volume ≥4000 mm³ (5.9 % vs 24.7%; p=<.001), and high ASPECTS of 8 to 10 (75.5% vs 44.4%; p=<.001). The overall rate of combined perioperative stroke/myocardial infarction/death was 1.1%, with no strokes recorded during the waiting time to carotid endarterectomy (CEA). Patients in group A had a lower rate of functional dependence at discharge (4.9% vs. 35.8%; p = <.001) and at 90 days after index stroke event (2.5% vs. 19.6%; p = <.001) versus those in group B. Using multivariate binary logistic regression, admission NIHSS>4 was significantly associated with higher odds of functional dependence at discharge (OR= 7.9, 95%CI= 2.7-18.5, p = <.001) and at 90 days (OR= 10.4, 95%CI= 2.7-19.3, p = .002).

CONCLUSIONS

NIHSS>4 at admission will increase the risk of having higher mRS scores both at hospital discharge and at 90 days after index stroke event. acute CEA was safe and feasible in patients with ischemic stroke, even if they had previously undergone intravenous thrombolysis.

Timing of Carotid Intervention in Symptomatic Carotid Artery Stenosis: A Systematic Review and Meta-Analysis

OBJECTIVE

This review aimed to analyse the timing of carotid endarterectomy (CEA) and carotid artery stenting (CAS) after the index event as well as 30 day outcomes at varying time periods within 14 days of symptom onset.

METHODS

A systematic review was performed according to the Preferred Reporting Items for Systematic reviews and Meta-analysis statement, comprising an online search of the Medline and Cochrane databases. Methodical quality assessment of the included studies was performed. Endpoints included procedural stroke and/or death stratified by delay from the index event and surgical technique (CEA/CAS).

RESULTS

Seventy-one studies with 232 952 symptomatic patients were included. Overall, 34 retrospective analyses of prospective databases, nine prospective, three RCT, three case control, and 22 retrospective studies were included. Compared with CEA, CAS was associated with higher 30 day stroke (OR 0.70; 95% CI 0.58 - 0.85) and mortality rates (OR 0.41; 95% CI 0.31 - 0.53) when performed ≤ 2 days of symptom onset. Patients undergoing CEA/CAS were analysed in different time frames (≤ 2 vs. 3 - 14 and ≤ 7 vs. 8 - 14 days). Expedited CEA (vs. 3 - 14 days) presented a sampled 30 day stroke rate of 1.4%; 95% CI 0.9 - 1.8 vs. 1.8%; 95% CI 1.8 - 2.0, with no statistically significant difference. Expedited CAS (vs. 3 - 14 days) was associated with no difference in stroke rate but statistically significantly higher mortality rate (OR 2.76; 95% CI 1.39 - 5.50).

CONCLUSION

At present, CEA is safer than transfemoral CAS within 2/7 days of symptom onset. Also, considering absolute rates, expedited CEA complies with the accepted thresholds in international guidelines. The ideal timing for performing CAS (when indicated against CEA) is not yet defined. Additional granular data and standard reporting of timing of intervention will facilitate future monitoring.

Successful implementation of best medical treatment for patients with asymptomatic carotid artery stenosis within a randomized controlled trial (SPACE-2)

Background

Asymptomatic carotid artery stenosis (ACS) can be treated with carotid endarterectomy (CEA), carotid artery stenting (CAS), or best medical treatment (BMT) only. For all treatment options, optimization of vascular risk factors such as arterial hypertension, hyperlipidemia, smoking, obesity, and insufficient physical activity is essential. Data on adherence to BMT and lifestyle modification in patients with ACS are sparse. The subject of this investigation is the implementation and quality of risk factor adjustment in the context of a randomized controlled trial.

Methods

A total of 513 patients in the prematurely terminated, randomized, controlled, multicenter SPACE-2 trial (ISRCTN 78592017) were analyzed within one year after randomization into 3 groups (CEA, CAS, and BMT only) for implementation of prespecified BMT recommendations and lifestyle modifications. Measurement time points were the screening visit and visits after one month (D30), 6 months (M6), and one year (A1). Differences between groups and follow-up visits (FUVs) relative to the screening visit were investigated.

Findings

For all FUVs, a significant increase in statin medication (91% at A1; p < 0.0001) was demonstrated to be associated with a significant decrease (p < 0.01) in cholesterol levels (median 167 mg/dl at A1) and LDL cholesterol levels (median 93 mg/dl at A1). The lowest cholesterol levels were achieved by patients in the BMT group. Seventy-eight percent of all patients reached predefined target cholesterol levels (< 200 mg/dl), with significantly better rates in the BMT group (p = 0.036 at D30). Furthermore, a significant decrease in arterial blood pressure at all FUVs (p < 0.05) was associated with a significant increase in antihypertensive medication (96% at A1, p < 0.0001). However, only 28% of patients achieved the predefined treatment goal of a systolic blood pressure of ≤ 130 mmHg. Forty-two of a total of 100 smokers at the screening visit quit smoking within one year, resulting in a significant increase in nonsmokers at all FUVs (p < 0.0001). Recommended HbA1c levels (< 7%) were achieved in 82% without significant changes after one year. Only 7% of obese (BMI > 25) patients achieved sufficient weight reduction after one year without significant changes at all FUVs (median BMI 27 at A1; p = 0.1201). The BMT group showed significantly (p = 0.024) higher rates of adequate physical activity than the intervention groups. Furthermore, after one year, the BMT group showed a comparatively significantly better implementation of risk factor modification (77%; p = 0.027) according to the treating physician.

Interpretation

SPACE-2 demonstrated sustained improvement in the noninterventional management of vascular risk factors in patients treated in a clinical trial by general practitioners, internists and neurologists. The best implemented treatment targets were a reduction in cholesterol and HbA1c levels. In this context, a significant increase in statin use was demonstrated. Blood pressure control missed its target but was significantly reduced by intensification of antihypertensive medication. Patients on BMT only had better adjusted lipid parameters and were more physically active. However, all groups failed to achieve sufficient weight reduction. Due to insufficient patient recruitment, the results must be interpreted cautiously.

Trial registration: ISRCTN Registry, ISRCTN78592017, Registered 16 June 2007, https://www.isrctn.com/search?q=78592017.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42466-021-00153-w.

A Systematic Review and Meta-analysis of Peri-Procedural Outcomes in Patients Undergoing Carotid Interventions Following Thrombolysis

OBJECTIVE

To evaluate the safety of carotid artery stenting (CAS) and carotid endarterectomy (CEA) after thrombolytic therapy (TT).

DATA SOURCES

Medline, Scopus, and Cochrane databases.

REVIEW METHODS

Systematic review and meta-analysis of studies involving patients who underwent CEA/CAS after TT.

RESULTS

In 25 studies (n = 147 810 patients), 2 557 underwent CEA (n = 2 076) or CAS (n = 481) following TT. After CEA, the pooled peri-procedural stroke/death rate was 5.2% (95% confidence interval [CI] 3.3 - 7.5) and intracranial haemorrhage (ICH) was 3.4% (95% CI 1.7 - 5.6). After CAS, the pooled peri-procedural stroke/death rate was 14.9% (95% CI 11.9 - 18.2) and ICH was 5.5% (95% CI 3.7 - 7.7). In case control studies comparing CEA outcomes in patients receiving TT vs. no TT, peri-procedural death/stroke was non-significantly higher after TT (4.3% vs. 1.5%; odds ratio [OR] 2.34, 95% CI 0.74 - 7.47), but ICH was significantly higher after TT (2.2% vs. 0.12%; OR 7.82, 95% CI 4.07 - 15.02), as was local haematoma formation (3.6% vs. 2.26%; OR 1.17, 95% CI 1.17 - 2.33). In case control studies comparing CAS outcomes in patients receiving TT vs. no TT, peri-procedural stroke/death was significantly higher after TT (5.2% vs. 1.5%; OR 8.49, 95% CI 2.12 - 33.95) as was ICH (5.4% vs. 0.7%; OR 7.48, 95% CI 4.69 - 11.92). Meta-regression analysis demonstrated an inverse association between the time interval from intravenous (IV) TT to undergoing CEA and the risk of peri-procedural stroke/death (p = .032). Peri-operative stroke/death was 13.0% when CEA was performed three days after TT and 10.6% when performed four days after TT, with the risk reducing to within the currently accepted 6% threshold after six-seven days had elapsed.

CONCLUSION

Peri-procedural ICH and local haematoma were significantly more frequent in patients undergoing CEA after TT (vs. no TT), although there were no randomised comparisons. Peri-procedural hazards were also significantly higher for CAS after TT. The inverse relationship between timing to CEA and peri-procedural stroke/death mandates careful patient selection and suggests that it may be safer to defer CEA for six-seven days after TT.