Relationship of pharmacotherapy and the incidence of embolic complications of carotid reconstructive surgery

Aim. To evaluate the relationship between lipid-lowering and antiplatelet therapy and the incidence of cerebral microembolism and related complications in open and endovascular revascularization of the carotid arteries (CA).

Material and methods. This single-center study involved patients with internal CA stenosis. The patients were divided into 2 groups depending on the surgery type performed: carotid endarterectomy (CEA)  — 163 patients; CA stenting (CAS)  — 71 patients. All patients underwent intraoperative transcranial Doppler monitoring to register cerebral embolism during CAS and CE.

Results. In CAS, microembolism episodes were observed in 66,2% vs 22,1% of patients in the CEA group (p=0,04), the largest number of which was recorded during catheterization of the internal CA and embolic filter installation (p=0,000). There were no significant differences between the groups in terms of the stroke incidence. In 8 patients in the CAS group and 1 patient in the CEA group, a transient ischemic attack was observed within 30 days after surgery (p=4x10-4 ). Intraoperative embolism was a predictor of a neurological event in the early postoperative period (odds ratio (OR), 33,08; 95% confidence interval (CI): 3,49-56,37 (p6 months before surgery reduces the likelihood of embolism by 4 times (OR 0,25; 95% CI: 0,11-0,58 (p=0,001), while lipid-lowering and antiplatelet therapy combination — by 12,5 times (OR, 0,08; 95% CI: 0,01-0,40 (p=0,001)).

Conclusion. Preoperative antiplatelet and statin therapy reduces the likelihood of embolism during the CA revascularization procedure.

Three-dimensional ultrasonographic evaluation of carotid artery plaque surface irregularity

INTRODUCTION

The aim of this study was to evaluate 3-dimensional (3D) ultrasonography (US) in determining the surface irregularity of carotid artery plaques.

MATERIAL AND METHODS

This study included 50 patients (20 females and 30 males) aged between 56 and 82 years with plaques in the carotid artery which were detected during routine neck ultrasound. Simultaneously these cases were evaluated in terms of plaque echogenicities and surface characteristics with 2D and 3D US.

RESULTS

3D imaging was successfully performed in 45 of the 50 cases and the technical success rate was 90%. A single plaque was detected in 64.4% of the patients, with the remaining 35.6% having more than one plaque. The lengths of the plaques ranged from 2 to 12 mm (mean: 3.98 ±1.70 mm); the widths ranged from 1.8 to 3.2 mm (mean: 2.11 ±0.37 mm). No significant difference was found between 2D and 3D plaque echo-structures (observer 1, p = 0.317; observer 2, p = 0.276), but there were significant differences between 2D and 3D plaque surface irregularities (observer 1, p = 0.002; observer 2, p = 0.004). The inter-observer agreement on 2D and 3D plaque echo-structure and surface irregularity was very good (k coefficients were 0.89 and 0.83, respectively, for echo-structure, and 0.91 and 0.95, respectively, for surface irregularity).

CONCLUSIONS

The present study shows that 3D US examination is a valuable non-invasive method for investigation of surface irregularity of carotid artery plaques.

Insufficient platelet inhibition and thromboembolic complications in patients with intracranial aneurysms after stent placement

OBJECT

Insufficient platelet inhibition has been associated with an increased incidence of thromboembolic complications in cardiology patients undergoing percutaneous coronary intervention. Data regarding the relationship between insufficient platelet inhibition and thromboembolic complications in patients undergoing neurovascular procedures remain controversial. The purpose of this study was to assess the relationship of insufficient platelet inhibition and thromboembolic complications in patients with intracranial aneurysm undergoing stent treatment.

METHODS

The authors prospectively recruited patients with intracranial aneurysms undergoing stent treatment and maintained the data in a database. MRI with diffusion-weighted sequences was performed within 24 hours of stent insertion to identify acute ischemic lesions. The authors used thromboelastography to assess the degree of platelet inhibition in response to clopidogrel and aspirin. Univariate and multivariate logistic regression analysis was used to identify potential risk factors of thromboembolic complications.

RESULTS

One hundred sixty-eight patients with 193 aneurysms were enrolled in this study. Ninety-one of 168 (54.2%) patients with acute cerebral ischemic lesions were identified by diffusion-weighted MRI. In 9 (5.4%) patients with ischemic lesions, transient ischemic attack or stroke was found at discharge, and these complications were found in 11 (6.5%) patients during the follow-up period. The incidence of periprocedural thromboembolic complications increased with resistance to antiplatelet agents, hypertension, hyperlipidemia, complete occlusion, and aneurysm of the anterior circulation. The multivariate regression analysis demonstrated that the anterior circulation and adenosine diphosphate (ADP) inhibition percentage were independent risk factors of perioperative thromboembolic complications. The maximum amplitude and ADP inhibition percentage were independent risk factors for thromboembolic complications during the follow-up period.

CONCLUSIONS

The ADP inhibition percentage is related to thromboembolic complications after stent placement for intracranial aneurysms. The increase of the ADP inhibition may decrease the risk of thromboembolic complications.

Pathology of embolic debris in carotid artery stenting

BACKGROUND

The relationship between magnetic resonance (MR) plaque imaging and the pathology of distal embolic debris is unknown. We aimed to evaluate the relationship between the pathology of embolic debris in the embolic filter during carotid artery stenting (CAS), MR plaque imaging, and new ischemic lesions on diffusion-weighted imaging (DWI).

METHOD

We prospectively reviewed the 36 patients who underwent CAS using a filter-type embolic protection device. Pathology of debris was categorized into thrombosis, inflammatory cells, elastic fiber, and calcification. We compared the clinical parameters, MR plaque imaging, and pathological characteristics of the embolic debris retained in the filter during CAS on univariate analysis.

RESULTS

Eleven patients had and 25 patients did not have new lesion on DWI. All of DWI-high lesions were identified in affected side middle cerebral artery territory. Embolic debris was microscopically confirmed in 28 patients (78%); thrombosis in 11 (31%), inflammatory cells in 13 (36%), elastic fiber in 12 (33%), and calcification in 9 (25%). Proportion of asymptomatic carotid stenosis, intra-operative bradycardia/hypotension, and inflammatory cells of debris were significantly higher in patients with new DWI-high lesions. There was no significant relationship between the pathological characteristics and MR plaque imaging of distal embolic debris.

CONCLUSIONS

Our study showed that new DWI-high lesions might be influenced by types of debris in the filter. The need for future studies specifically examine the association of pathology of debris and findings of MR plaque imaging with new DWI-high lesions during CAS is emphasized.

Stabilization technique for real-time high-resolution vascular ultrasound using frequency domain interferometry

We have proposed an ultrasound imaging method based on frequency domain interferometry (FDI) with an adaptive beamforming technique to depict real-time high-resolution images of human carotid artery. Our previous study has investigated the performance of the proposed imaging method under an ideal condition with a high signal-to-noise ratio (SNR). In the present study, we propose a technique that has the potential to improve accuracy in estimating echo intensity using the FDI imaging method. We investigated the performance of the proposed technique in a simulation study that two flat interfaces were located at depths of 15.0 and 15.2 mm and white noise was added. Because the -6 dB bandwidth of the signal used in this simulation study is 2.6 MHz, the conventional B-mode imaging method failed to depict the two interfaces. Both the conventional and proposed FDI imaging methods succeeded to depict the two interfaces when the SNR ranged from 15 to 30 dB. However, the average error of the estimated echo intensity at the interfaces using the conventional FDI imaging method ranged from 7.2 to 10.5 dB. In contrast, that using the FDI imaging method with the proposed technique ranged from 2.0 to 2.2 dB. The present study demonstrates the potential of the FDI imaging method in depicting robust and high-range-resolution ultrasound images of arterial wall, indicating the possibility to improve the diagnosis of atherosclerosis in early stages.

Dilation of the Internal Carotid Artery at the Entrance to the Carotid Canal following Carotid Artery Stenting Predicts Postprocedural Hyperperfusion

OBJECTIVE

Ischemic stroke and hyperperfusion (HP) are the most frequent and important complications in carotid artery stenosis surgery. Carotid artery stenting (CAS) has replaced carotid endarterectomy in high medical risk patients. Prior to CAS, initial angiographic findings disclose a small caliber internal carotid artery (IC) due to stenosis, but after the stenosis is relieved, the diameter of the IC becomes enlarged. We investigated whether a change in the IC diameter was related to ischemic complication and HP using cerebral blood flow single photon emission computed tomography (SPECT).

METHODS

From February 2008 to December 2009 we consecutively performed 39 CAS on 35 patients. We retrospectively analyzed the relationship between changes at the level before the entry to the petrous bone canal of the IC and stenosis of the etiological artery, improvement in stenosis, HP and postintervention diffusion-weighted image high-intensity lesions. Statistical analyses comprised Wilcoxon/Kruskal-Wallis analysis, analysis of variance and a multivariate logistic analysis.

RESULTS

A total of 9 cases showed HP in SPECT. Severity of IC stenosis and change in the IC at the level before the entry to the petrous bone canal were related with statistical significance to HP. Other factors did not correlate with HP.

CONCLUSION

Procedure-related dilation of the IC at the level before the entry to the petrous bone canal occurred due to release of the etiological stenosis. This finding can also support the prediction of HP.

Association between silent embolic cerebral infarction and continuous increase of P2Y12 reaction units after neurovascular stenting

OBJECTIVES

Endovascular procedures are one of the important treatment options for steno-occlusive arteries in ischemic stroke patients. However, embolic complications after such procedures are always a concern. The authors investigated the association between serial change of residual platelet reactivity and silent embolic cerebral infarction (SECI) after endovascular treatment.

METHODS

Ischemic stroke patients undergoing stenting of intra- or extracranial arteries were recruited prospectively. Residual platelet reactivity, represented by aspirin reaction units (ARUs) and P2Y12 reaction units (PRUs), was measured serially (6 hours before, immediately after, and 24 hours after the procedure). A loading dosage of aspirin (500 mg) and/or clopidogrel (300 mg) was given 24 hours before the procedure to patients naïve to antiplatelet agents, whereas the usual dosage (aspirin 100 mg and clopidogrel 75 mg) was continued for patients who had previously been taking these agents for more than a week. Diffusion-weighted MRI was performed before and 24 hours after the procedure to detect new SECIs. Clinical characteristics, baseline ARU and PRU values, and the change in ARU and PRU values after stenting were compared between patients with and without SECIs.

RESULTS

Among 69 consecutive patients who underwent neurovascular stent insertion, 41 patients (59.4%) had poststenting SECIs. The lesion was located only at the vascular territory of the stented vessel in 21 patients (51.2%), outside the stented vessel territory in 8 patients (19.5%), and both inside and outside in 12 patients (29.3%). The occurrence of SECIs was not associated with the baseline ARU or PRU value, but was associated with PRU increase after stenting (36 ± 73 vs -12 ± 59, p = 0.007), deployment of a longer stent (31.1 ± 16.5 mm vs 21.8 ± 9.9 mm, p = 0.01), and stent insertion in extracranial arteries (78.1% vs 45.2%, p = 0.008). Stent length (OR 1.066, p = 0.01) and PRU change (OR 1.009, p = 0.04) were independently associated with the occurrence of SECI.

CONCLUSIONS

Residual platelet reactivity after dual antiplatelet treatment measured before stenting did not predict poststenting SECI. However, the longer stent and the serial increase of PRU values after stenting were related to SECI. Continuous increase of platelet activation after endovascular procedure may be important in poststent cerebral infarction.

Comparison between proximal versus distal protection devices in 287 cases of carotid revascularization using angioplasty and stenting: periprocedure complications, morbidity, and mortality

BACKGROUND

Embolic protection devices may decrease periprocedural thromboembolic complications during carotid angioplasty and stenting (CAS). When using proximal-protection devices (PPDs), protection starts before crossing the lesion. However, in the medical literature, its use is scarcely reported compared with that of distal-protection filters (DPDs). The objective of this study was to compare periprocedure complications, morbidity, and mortality among 287 consecutive cases of CAS performed with PPDs or DPDs.

PATIENTS AND METHODS

This was a retrospective analysis of 287 patients treated with CAS at our hospital between January 2006 and March 2012. Periprocedure complications, morbidity, and mortality at 30 days, including ischemic stroke or transient ischemic attack, reperfusion syndrome, myocardial infarction (MI), and death, were globally registered, and the results in PPD and DPD groups were compared.

RESULTS

Two hundred eight patients were treated with DPD and 79 with PPD; 80.8 % were symptomatic. CAS procedures performed with PPD presented a statistically significant greater grade of stenosis than those with DPD (82.5 vs. 74.5 %, p < 0.001). Death rates were 1.9 and 1.3 %; stroke rates were 4.3 and 3.8 %; MI rates were 1.4 and 1.3 %; and total morbidity and mortality rates were 6.2 and 5 % (DPD and PPD groups, respectively); all differences were nonstatistically significant. No statistical difference was found between symptomatic and asymptomatic patients.

CONCLUSION

Carotid angioplasty and stenting is a safe procedure to treat carotid disease in our patients. PPDs are not always associated with a greater risk of periprocedure complications, morbidity, and mortality than DPDs despite the greater grade of carotid stenosis in the PPD group. This observation may be of interest in the design of future studies with CAS.

Histological Features of Carotid Plaque in Patients With Ocular Ischemia Versus Cerebral Events

Background and Purpose—

Patients with carotid artery stenosis and ocular ischemic events have a much lower risk of future ipsilateral ischemic stroke on medical treatment and lower procedural risks for endarterectomy and stenting than patients with cerebral ischemic events, and are closer in risk to patients with asymptomatic stenosis. The reasons for this difference in prognosis are not fully understood, but may reflect differences in carotid plaque pathology.

Methods—

In consecutive patients undergoing carotid endarterectomy for recently symptomatic stenosis (Oxford Plaque Study, Athero-Express Study), we compared carotid plaque histology (using validated semiquantitative scales) in those who had cerebral events within the last 6 months (n=1317) versus those with ocular events only (n=323).

Results—

Compared with plaques from patients with ocular events only, those from patients with cerebral events had significantly more large lipid core (odds ratio [OR], 1.38; 95% confidence interval [CI], 1.05–1.82; P =0.02), inflammation (OR, 1.32; 95% CI, 1.02–1.72; P =0.04) and overall plaque instability (OR, 1.37; 95% CI, 1.05–1.80; P =0.02), and less fibrous content (OR, 0.71; 95% CI, 0.54–0.92; P =0.01), and calcification (OR, 0.70; 95% CI, 0.54–0.91; P =0.008). The overall number of histological features known to be associated with vulnerable plaque was greater in patients with cerebral events than in those with ocular events ( P =0.002).

Conclusions—

Carotid plaques from patients undergoing endarterectomy for previous ocular ischemic events have fewer vulnerable plaque features than those from patients with recent cerebral ischemic events, possibly explaining some of the differences in risk of stroke between these groups.