The detrimental impact of silent cerebral infarcts on asymptomatic carotid endarterectomy outcome

Investigating the Association of Carotid Atherosclerotic Plaque MRI Features and Silent Stroke After Carotid Endarterectomy

BACKGROUND

The predictive value of carotid plaque characteristics for silent stroke (SS) after carotid endarterectomy (CEA) is unclear.

OBJECTIVE

To investigate the associations between carotid plaque characteristics and postoperative SS in patients undergoing CEA.

STUDY TYPE

Prospective.

POPULATION

One hundred fifty-three patients (mean age: 65.4 ± 7.9 years; 126 males) with unilateral moderate-to-severe carotid stenosis (evaluated by CT angiography) referred for CEA.

FIELD STRENGTH/SEQUENCE

3 T, brain-MRI:T2-PROPELLER, T1-/T2-FLAIR, diffusion weighted imaging (DWI) and T2*, carotid-MRI:black-blood T1-/T2W, 3D TOF, Simultaneous Non-contrast Angiography intraplaque hemorrhage.

ASSESSMENT

Patients underwent carotid-MRI within 1-week before CEA, and brain-MRI within 48-hours pre-/post-CEA. The presence and size (volume, maximum-area-percentage) of carotid lipid-rich necrotic core (LRNC), intraplaque hemorrhage (Type-I/Type-II IPH) and calcification were evaluated on carotid-MR images. Postoperative SS was assessed from pre-/post-CEA brain DWI. Patients were divided into moderate-carotid-stenosis (50%-69%) and severe-carotid-stenosis (70%-99%) groups and the associations between carotid plaque characteristics and SS were analyzed.

STATISTICAL TESTS

Independent t test, Mann-Whitney U-test, chi-square test and logistic regressions (OR: odds ratio, CI: confidence interval). P value <0.05 was considered statistically significant.

RESULTS

SS was found in 8 (16.3%) of the 49 patients with moderate-carotid-stenosis and 21 (20.2%) of the 104 patients with severe-carotid-stenosis. In patients with severe-carotid-stenosis, those with SS had significantly higher IPH (66.7% vs. 39.8%) and Type-I IPH (66.7% vs. 38.6%) than those without. The presence of IPH (OR 3.030, 95% CI 1.106-8.305) and Type-I IPH (OR 3.187, 95% CI 1.162-8.745) was significantly associated with SS. After adjustment, the associations of SS with presence of IPH (OR 3.294, 95% CI 1.122-9.669) and Type-I IPH (OR 3.633, 95% CI 1.216-10.859) remained significant. Moreover, the volume of Type-II IPH (OR 1.014, 95% CI 1.001-1.028), and maximum-area-percentage of Type-II IPH (OR 1.070, 95% CI 1.002-1.142) and LRNC (OR 1.030, 95% CI 1.000-1.061) were significantly associated with SS after adjustment. No significant (P range: 0.203-0.980) associations were found between carotid plaque characteristics and SS in patients with moderate-carotid-stenosis.

DATA CONCLUSIONS

In patients with unilateral severe-carotid-stenosis, carotid vulnerable plaque MR features, particularly presence and size of IPH, might be effective predictors for SS after CEA.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 2.

Clamped Carotid Dissection Can Reduce Postoperative Stroke After Carotid Endarterectomy

Background: The outcomes of carotid endarterectomy (CEA) are constantly reported in a multitude of studies; however, the specific causes of perioperative stroke have been scarcely investigated. The aim of the present study was to analyze and categorize the causes of perioperative strokes after CEA. Methods: All CEAs performed from 2006 to 2019 in a single center were collected. CEA was routinely performed under general anesthesia, with routine shunting and patching, using cerebral near-infrared spectroscopy monitoring. Carotid exposure technique was classified as either clamped-dissection (CD) or preclamping-dissection (PCD) if the carotid bifurcation was dissected after or prior to carotid clamping. Perioperative and 30-day strokes and their possible mechanisms were evaluated according to preoperative symptoms and surgical technique adopted. Results: Among 1760 CEAs performed, 30 (1.7%) perioperative strokes occurred. 14 (47%) were identified upon emergence from general anesthesia, and 16 (53%) were noted in the first 30 days following intervention. Stroke etiology was categorized as follows: technical (acute thrombosis or intimal flap or due to intraoperative complications), embolic (no recognized technical defect), hemorrhagic, or contralateral. Symptomatic patients had a significantly higher rate of any type of stroke than asymptomatic patients (3.8% vs 0.9%, P = .0001). CD was protective for postoperative stroke (0.9% vs 3.1%, P = .001) in both symptomatic and asymptomatic patients (2.5% vs 5.9%, P = .05; 0.4% vs 1.9%, P = .005), particularly for the cohort in which symptomatic patients (0.7% vs 3.2%, P = .04) suffered postoperative embolic stroke. Conclusion: Perioperative stroke in CEA may be multifactorial in etiology, including a result of technical errors. A CD technique may help reduce the incidence of perioperative stroke.

Silent brain infarcts and white matter lesions in patients with asymptomatic carotid stenosis

The association of carotid atherosclerosis with silent brain infarcts (SBIs) and white matter lesions (WMLs) currently remains unknown. This study aims to compare SBIs, deep white matter lesions (DWMLs), and periventricular white matter lesions (PWMLs) in ipsilateral and contralateral hemispheres to internal carotid artery (ICA) stenosis, and investigate their association with stenosis grade in patients with asymptomatic ≥ 50% unilateral extracranial ICA stenosis. Patients without previous history of stroke and/or transient ischemic attack who had ≥ 50% stenosis in unilateral ICA on carotid color Doppler ultrasound were enrolled in the study. Patient demographics, vascular risk factors and ICA stenosis grades; number, location, and size of SBIs, DWMLs, and PWMLs in ICA territory were evaluated in both hemispheres using magnetic resonance imaging of the brain. Of the 69 patients, 53 had 50-69% (76.8%) and 16 had ≥ 70% (23.2%) unilateral ICA stenosis. There was no statistically significant difference in SBIs between ipsilateral and contralateral hemispheres to ≥ 50% ICA stenosis. Comparison of ICA stenoses as 50-69% and ≥ 70% revealed a greater number of patients with SBI in ipsilateral hemisphere to ≥ 70% stenosis compared to contralateral (p = 0.025). The number of SBIs was also higher in ipsilateral hemisphere to ≥ 70% stenosis compared to contralateral (p = 0.022). While DWMLs and PWMLs did not differ between hemispheres, frequency of Fazekas grade 1 DWMLs was lower in ipsilateral hemisphere to either 50-69% or ≥ 70% ICA stenosis compared to contralateral (p = 0.035 and p = 0.025, respectively). Results of the present study indicate that stenosis grade may be relevant in the association between asymptomatic carotid stenosis and SBIs, and ≥ 70% stenosis may pose a risk of SBI development.

Impact of cerebral ischemic lesions on the outcome of carotid endarterectomy

Patients with carotid artery stenosis (CAS) are commonly defined as asymptomatic or symptomatic according with their neurological conditions, however, emerging evidences suggest stratifying patients according also with the presence of cerebral ischemic lesions (CIL). In asymptomatic patients, the presence of CIL increases the risk of future neurologic event from 1% to 4% per year, leading to a stronger indication to carotid revascularization. In symptomatic patients, the presence of CIL does not seem to influence the outcome of the carotid revascularization if the volume of the lesion is small (<4,000 mm³); the benefit of the revascularization is also more significant if performed within 2 weeks from the index event. However, high volume (>4,000 mm³) CIL are associated in some experiences with a higher risk of carotid revascularization suggesting to delay the carotid revascularization for at least 4 weeks. As a matter of fact, the evaluation of CIL dimensions and characteristics in patients with CAS gives to the physician involved in the treatment a valuable adjunctive tool in the choice of the ideal treatment.

Brain imaging biomarkers of carotid artery disease

Extracranial carotid artery atherosclerotic disease is a major contributor to ischemic stroke. Carotid atherosclerotic disease can present with a spectrum of findings ranging from mild carotid intima-media thickness to high-risk vulnerable carotid plaque features and carotid stenosis. Before leading to clinically overt stroke or transient ischemic attack, there may be other markers of downstream ischemia secondary to carotid atherosclerotic disease. In this review article, we will review some of the imaging findings that may be seen downstream to carotid artery disease on various imaging modalities, including hemodynamic and perfusional abnormalities which may be seen on CT, MR, or using other advanced imaging techniques, white matter hyperintensities on brain imaging, silent or covert brain infarctions, cerebral microbleeds, and regional and generalized cerebral volume loss. Many of these imaging findings are seen routinely on brain magnetic resonance imaging in patients without overt clinical symptoms. Despite frequently being asymptomatic, many of these imaging findings are also strongly associated with increased risk of future stroke, cognitive impairment, and even mortality. We will review the existing evidence underpinning the associations between these frequently encountered imaging findings and carotid artery atherosclerotic disease. Future validation of these imaging findings could lead to them being powerful biomarkers of cerebrovascular health.

Predictors and Consequences of Silent Brain Infarction in Patients with Asymptomatic Carotid Stenosis

AIM

Silent brain infarction (SBI) is associated with an increased risk of stroke in patients with asymptomatic carotid stenosis (ACS), and is therefore one of the criteria for performing carotid endarterectomy (CEA). Despite an extensive literature, this issue is still a matter of debate. Aim of the present work was to evaluate incidence and predictors of SBI in patients undergoing CEA for ACS, and to investigate its possible impact on CEA outcome.

METHODS

All patients submitted to CEA in a single academic center from 2005 to 2019 were prospectively inserted into a specific database. The presence of SBI was evaluated by preoperative computed tomography (CT), considering exclusively infarctions in the carotid territories from an athero-embolic source. Preoperative characteristics were investigated as possible risk factor for SBI at the uni- and multivariate analysis. The impact of SBI on stroke occurrence after CEA was also evaluated.

RESULTS

In the designated period, over a total of 1288 ACS considered and submitted to CEA, 105 (8.2%) were associated with SBI. Male sex, hypertension, dyslipidaemia, smoking, contralateral carotid occlusion and severity of carotid stenosis were associated with SBI at the univariate analysis; preoperative statin therapy showed to be a protective factor. At the multivariate analysis, contralateral carotid occlusion and severity of stenosis were independently associated with SBI (OR: 3.16, 95%CI 1.62-6.18, P=.001; OR: 1.04, 95%CI 1.01-1.07, P=.004, respectively), with statin therapy confirmed as a protective factor (OR: 0.60, 95%CI: 0.40-0.92, P=.002). Overall post-CEA stroke rate was 0.9%, with a higher post-operative risk independently predicted by the presence of SBI (OR:4.23, 95%CI: 1.40-12.73, P=.01).

CONCLUSION

SBI is present in 8% of patients with ACS, and is significantly associated with contralateral carotid occlusion and severity of the carotid stenosis. Statin therapy reduces the occurrence of this phenomenon. The presence of SBI should be carefully considered in indication to CEA since it significantly increases the surgical risk.

The benefit of deferred carotid revascularization in patients with moderate-severe disabling cerebral ischemic stroke

OBJECTIVE

Symptomatic carotid artery stenosis needs revascularization within 2 weeks by carotid endarterectomy (CEA) to reduce the risk of symptom recurrence; however, the optimal timing of intervention is yet to be defined in patients with large-volume cerebral ischemic lesion (LVCIL) and modified Rankin scale (mRS) score ≥3. The aim of this study was to determine the most appropriate timing for CEA in patients with a recent stroke and LVCIL.

METHODS

Data from patients with symptomatic carotid stenosis with LVCIL and mRS score of 3 or 4 from 2007 to 2017 were considered. Patients were submitted to CEA if they had a stable clinical condition and life expectancy >1 year. LVCIL was defined as a cerebral ischemic lesion of volume >4000 mm³. Perioperative stroke and death were evaluated by stratifying for timing of CEA by χ² test and multiple logistic regression. Patients with similar characteristics (LVCIL and mRS score of 3 or 4) unfit for CEA served as the control group for recurrence of stroke at 1-year follow-up.

RESULTS

In an 11-year period, of a total 4020 CEAs, 126 (2.9%) were performed in patients with a moderate stroke and LVCIL occurring in the same admission. The patients' median age was 69 years (interquartile range [IQR], 10 years); 72% (91) were male, with mRS score of 3 (IQR, 1) and LVCIL volume of 20,000 mm³ (IQR, 47,000 mm³). The median time elapsed from symptoms to CEA was 7 weeks (IQR, 8 weeks). Overall perioperative stroke/death was 7.3% (eight strokes and one death). By selective timing evaluation of the postoperative events, CEA performed within 4 weeks was associated with a significantly higher rate of stroke/death compared with patients operated on after 4 weeks: 11.9% (8/67) vs 1.7% (1/59; P = .03). By logistic regression, CEA within 4 weeks was an independent (from sex, cerebral ischemic lesion volume, dyslipidemia, and carotid stenosis) predictor of postoperative stroke/death (odds ratio, 8.2; 95% confidence interval, 1.01-73). In the same period, 101 patients were considered unfit for CEA for dementia (n = 22), severe comorbidities (n = 55), or short (<1-year) life expectancy (n = 24), and 43 (43%) survived at 1 year. At 1 year, the perioperative/recurrent stroke after CEA vs patients unfit for CEA was similar (6.2% vs 13.9%; P = .11), but CEA performed after 4 weeks led to significantly lower perioperative/recurrent stroke (1.7% vs 13.9%; P = .02).

CONCLUSIONS

The surgical risk of CEA in patients with a recent moderate-severe ischemic stroke and LVCIL is high. However, if the intervention is delayed >4 weeks, its benefit seems significant.

Cerebral Small Vessel Disease in Standard Pre-operative Imaging Reports Is Independently Associated with Increased Risk of Cardiovascular Death Following Carotid Endarterectomy

OBJECTIVE

Cerebral white matter lesions (WMLs) and lacunar infarcts are surrogates of cerebral small vessel disease (SVD). WML severity as determined by trained radiologists predicts post-operative stroke or death in patients undergoing carotid endarterectomy (CEA). It is unknown whether routine pre-operative brain imaging reports as part of standard clinical practice also predict short and long term risk of stroke and death after CEA.

METHODS

Consecutive patients from the Athero-Express biobank study that underwent CEA for symptomatic high degree stenosis between March 2002 and November 2014 were included. Pre-operative brain imaging (computed tomography [CT] or magnetic resonance imaging [MRI]) reports were reviewed for reporting of SVD, defined as WMLs or any lacunar infarcts. The primary outcome was defined as any stroke or any cardiovascular death over three year follow up. The secondary outcome was defined as the 30 day peri-operative risk of stroke or cardiovascular death.

RESULTS

A total of 1038 patients were included (34% women), of whom 659 (63.5%) had CT images and 379 (36.5%) MRI images available. Of all patients, 697 (67%) had SVD reported by radiologists. Patients with SVD had a higher three year risk of cardiovascular death than those without (6.5% vs. 2.1%, adjusted HR 2.52 [95% CI 1.12-5.67]; p = .026) but no association was observed for the three year risk of stroke (9.0% vs. 6.7%, for patients with SVD vs. those without, adjusted HR 1.24 [95% CI 0.76-2.02]; p = .395). No differences in 30 day peri-operative risk were observed for stroke (4.4% vs. 2.9%, for patients with vs. those without SVD; adjusted HR 1.49 [95% CI 0.73-3.05]; p = .28), and for the combined stroke/cardiovascular death risk (4.4% vs. 3.5%, adjusted HR 1.20 [95% CI 0.61-2.35]; p = .59).

CONCLUSION

Presence of SVD in pre-operative brain imaging reports can serve as a predictor for the three year risk of cardiovascular death in symptomatic patients undergoing CEA but does not predict peri-operative or long term risk of stroke.

Asymptomatic carotid stenosis and concomitant silent brain infarctions

Objectives

This review aims to clarify (1) the definition of silent brain infarct (SBI), (2) the diagnostic criteria of SBI using magnetic resonance imaging (MRI), (3) the prevalence of patients with asymptomatic carotid stenosis and SBI based on MRI assessment, (4) the association of SBI and asymptomatic carotid stenosis and the risk of stroke compared to patients without SBI, (5) the association between development of dementia/cognitive impairment in people with asymptomatic carotid stenosis and SBI, and (6) the evidence for treating patients with carotid stenosis and SBI.

Methods

A systematic search of PubMed and Scopus including all studies published from 2000 to 2018 and written in English.

Results

No consensus of the definition and diagnostic criteria for SBI was found. The prevalence of SBI in asymptomatic carotid patients is 17–33.3%. SBI is a significant risk factor for future stroke, OR 4.6 (95% CI: 3.0–7.2; p < 0.0001). One substudy showed that immediate CEA is beneficial compared to delayed CEA in these patients, showing a 45% reduction in annual stroke rate from 1.5%/year to 0.7%/year.

Conclusion

This review emphasizes the need to standardize the definition and diagnostic criteria of SBI on MRI. Current evidence suggests an increased risk and a small potential benefit of offering carotid endarterectomy to patient with silent brain infarct. Prospective studies are warranted to elucidate these issues further.

The different scenarios of urgent carotid revascularization for crescendo and single transient ischemic attack

OBJECTIVE

Carotid stenosis with crescendo-transient-ischemic-attack (cTIA) requires a prompt intervention to reduce the stroke risk. Few data are reported in literature about cTIA suggesting a different perioperative risk compared with patients with single TIA (sTIA). This study aimed to compare the outcome of carotid endarterectomy (CEA) in patients with TIA (single/crescendo) and evaluate the outcome risk-factors.

METHODS

Data from two tertiary hospitals for vascular treatment were analyzed from 2007 to 2016. All patients with TIA subjected to CEA were considered, comparing the 30-day postoperative stroke and stroke/death in patients with cTIA and sTIA, particularly in the urgent (≤48 h) setting.

RESULTS

On a total of 3866 CEA, 888 (23%) were performed in symptomatic patients and 515 for TIA: 365 (71%) patients with sTIA and 150 (29%) with cTIA. When compared with sTIA, cTIA patients were younger and less frequently affected by coronary disease, dyslipidemia, and chronic pulmonary disease; however, contralateral carotid occlusion was more common (20% vs. 10%, P = .004; 56% vs. 46, P = .03; 16% vs. 7%, P = .01; >80 years 26% vs. 16%, P = .01 and 2% vs. 10%, P = .001; respectively). Postoperative stroke and stroke/death were significantly higher in cTIA compared with sTIA (5.3% vs. 1.6%, P = .02 and 6.0% vs. 2.2%, P = .03; respectively). Urgent CEA was performed in 58% ( n: 87) cTIA and in 11% ( n: 56) sTIA( P<.01). The urgent setting did not influence the stroke and stroke/death rate of CEA for sTIA (3.6% vs. 1.3%, P = .21 and 3.6% vs. 1.9%, P = .44, respectively), but was associated with lower rate of events in cTIA (1.1%vs. 11.1%, P = .01 and 2.3% vs. 11.1%, P = .03, respectively). This beneficial effect in patients with cTIA treated within 48-h was confirmed also by multivariate analysis (OR: 0.09, 95% CI: 0.76-0.01, P=.02).

CONCLUSIONS

cTIA subjected to CEA have a higher stroke and stroke/death risk compared with patients with sTIA. The urgent setting seems to reduce the stroke/death rate cTIA; for sTIA with a stable neurological condition, the timing of CEA did not influence the outcome.

The Value of Carotid Endarterectomy as a Learning Tool for Trainees

BACKGROUND

Carotid endarterectomy (CEA) intervention needs a specific training and a sufficient learning curve to obtain optimal results in terms of outcome. A formative program was settled up in a single academic center to optimize training of standard CEA procedures. This study aims to evaluate the 11-year results of the teaching CEA program.

METHODS

The trainees CEA teaching program is carried on during the 5-year vascular surgery residency period, and it is stratified as follows: learning theory and intervention assistance (minimum 50 procedures per year) in the first and second residency year; performing CEA as second operator in the third and fourth residency year (minimum 50 procedures per year); CEA execution as first operator with attending supervision in the last residency year. All CEA procedures from 2005 to 2015 were retrospectively collected and the 30-day results were compared according to the expertise of the first operator: experienced vascular surgeons (EVSs) versus trainees. All CEA procedures were performed in general anesthesia, with routine shunting and patching.

RESULTS

In the study period, 1,379 (361 [26.2%] symptomatic; 1,018 [73.8%] asymptomatic) CEAs were performed. Trainees performed 199 (14.4%) CEAs as first operator. Patients submitted to CEA by trainees were similar in terms of preoperative clinical characteristics except for the patients' age (trainees 72.4 years versus EVS 70.8 years, P = 0.02) and smoking history (trainees 30.7% versus EVS 24.1%, P = 0.04). The 30-day complication rates were similar in CEA performed by trainees versus EVS: stroke 0.5% vs. 1.1%, P = 0.5; death 0.0% vs. 0.5%, P = 0.6; stroke/death 0.5% vs. 1.7%, P = 0.24; hematoma 3.0% vs. 2.2%, P = 0.48; and cranial nerve injury 9.0% vs. 7.8%, P = 0.47, respectively. The intervention time was significantly longer in CEAs performed by trainees compared with EVS: 104 ± 1.9 min versus 98 ± 1.0 min, P = 0.02.

CONCLUSIONS

With a defined CEA teaching program, trainees can obtain results similar to those of more experienced surgeons in terms of clinical outcome at the price of an increased intervention time.

Relationship between Calcification and Vulnerability of the Carotid Plaques

BACKGROUND

Carotid plaques with a high degree of calcification are usually considered at low embolic risk. However, since a precise evaluation of the extent of calcification is not possible preoperatively through duplex ultrasound and postoperatively by conventional histological examination due to the decalcification process, the relationship between the amount of calcium involvement and plaque vulnerability has not been evaluated yet. This study aims to correlate the extent of carotid plaque calcification with clinical, radiological, and histological complications.

METHODS

Symptomatic and asymptomatic consecutive patients submitted to carotid endarterectomy between January to December 2014 were included in the study. The amount of carotid calcification was assessed at preoperative computed tomography (CT) through measurement of thickness and circumferential calcium extension and graded from 1 to 8 accordingly (Babiarz classification). Patients were then categorized into 2 groups (low-level group: grade 1-5; high-level group: grade 6-8) and correlated with clinical characteristics and ipsilateral cerebral ischemic lesions at CT. Vulnerability of the plaque was assessed histologically according with American Heart Association (AHA) Classification. Results were overall blindly correlated.

RESULTS

One hundred five patients (81% male; age: 73 ± 8 years) were enrolled in the study. Forty (38%) were symptomatic and 43 (40%) had an ipsilateral focal lesion at preoperative cerebral CT. Thirty-six (38%) patients had high-level carotid calcification degree at CT scan. At histological analysis, 56 (56%) plaques were considered complicated (AHA type VI). Patients with high-level and low-level carotid calcification had similar epidemiological risk factors, preoperative neurological symptoms, and histological complications (17% vs. 15%, P = 0.76 and 50% vs. 55%, P = 0.62, respectively). The high-level calcification group showed a significantly higher incidence of ipsilateral cerebral lesions at preoperative CT (56% vs. 32%, P = 0.01).

CONCLUSIONS

A high level of calcification of the carotid plaque is not necessarily associated with lower vulnerability: the incidence of preoperative neurological symptoms and histological complications is similar in patients with and without extensive carotid plaque calcification. Cerebral ischemic lesions may be even more frequent in the presence of highly calcified plaques.