Sébastien Soize

Techniques for Endovascular Treatment of Acute Ischemic Stroke: From Intra-Arterial Fibrinolytics to Stent-Retrievers

Early recanalization of occluded vessels in acute ischemic stroke (AIS) either by intravenous thrombolysis or endovascular revascularization has been shown to be associated with improved clinical outcome and reduced mortality.1 Initial works on endovascular treatment (EVT) of AIS was published in the 1980s.2,3 Since then, the endovascular techniques for AIS treatment have tremendously improved, advancing from intra-arterial administration of thrombolytic drugs to first-generation mechanical thrombectomy devices (Merci clot retriever and Penumbra clot aspiration) and more recently to second-generation mechanical thrombectomy devices (stent-retrievers; Figure 1). Introduction of various tools and techniques in EVT for AIS will, for obvious reasons, affect the efficacy and safety. Figure 1. Evolution of endovascular techniques for acute ischemic stroke and clinical trials. IMS indicates Interventional Management of Stroke; MERCI, Mechanical Embolus Removal in Cerebral Ischemia; MR CLEAN, Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands; PROACT, Prolyse in Acute Cerebral Thromboembolism; SWIFT, Solitaire With the Intention for Thrombectomy; and TREVO, Thrombectomy Revascularization of Large Vessel Occlusions in Acute Ischemic Stroke. On the other hand, intravenous thrombolysis was evaluated in several large randomized trials and was shown to improve clinical outcome at 90 days if treatment was initiated within 3 hours of stroke onset.4 Subsequently, the European Cooperative Acute Stroke Study (ECASS) III showed the benefit of intravenous thrombolysis between 3 and 4.5 hours.5 After establishing the efficacy of intravenous recombinant tissue-type plasminogen activator (r-tPA) in the treatment of AIS, EVT had to be evaluated against intravenous treatment. A long time elapsed before the results of the first randomized controlled trials were published in 2013 demonstrating no major difference between intravenous r-tPA treatment and EVT for AIS.6–8 Noteworthy, these trials had several limitations including the fact that all EVT were approved for use.9 …

Follow-up of intracranial aneurysms treated by flow diverter: comparison of three-dimensional time-of-flight MR angiography (3D-TOF-MRA) and contrast-enhanced MR angiography (CE-MRA) sequences with digital subtraction angiography as the gold standard

Background and purpose Follow-up of intracranial aneurysms treated by flow diverter with MRI is complicated by imaging artifacts produced by these devices. This study compares the diagnostic accuracy of three-dimensional time-of-flight MR angiography (3D-TOF-MRA) and contrast-enhanced MRA (CE-MRA) at 3 T for the evaluation of aneurysm occlusion and parent artery patency after flow diversion treatment, with digital subtraction angiography (DSA) as the gold standard. Materials and methods Patients treated with flow diverters between January 2009 and January 2013 followed by MRA at 3 T (3D-TOF-MRA and CE-MRA) and DSA within a 48 h period were included in a prospective single-center study. Aneurysm occlusion was assessed with full and simplified Montreal scales and parent artery patency with three-grade and two-grade scales. Results Twenty-two patients harboring 23 treated aneurysms were included. Interobserver agreement using simplified scales for occlusion (Montreal) and parent artery patency were higher for DSA (0.88 and 0.61) and CE-MRA (0.74 and 0.55) than for 3D-TOF-MRA (0.51 and 0.02). Intermodality agreement was higher for CE-MRA (0.88 and 0.32) than for 3D-TOF-MRA (0.59 and 0.11). CE-MRA yielded better accuracy than 3D-TOF-MRA for aneurysm remnant detection (sensitivity 83% vs 50%; specificity 100% vs 100%) and for the status of the parent artery (specificity 63% vs 32%; sensitivity 100% vs 100%). Conclusions At 3 T, CE-MRA is superior to 3D-TOF-MRA for the evaluation of aneurysm occlusion and parent artery patency after flow diversion treatment. However, intraluminal evaluation remains difficult with MRA regardless of the sequence used.

Outcome after mechanical thrombectomy using a stent retriever under conscious sedation: Comparison between tandem and single occlusion of the anterior circulation

BACKGROUND AND PURPOSE In acute ischemic stroke patients, internal carotid artery/middle cerebral artery (ICA/MCA) occlusion in tandem predicts a poor outcome after systemic thrombolysis. This study aimed to compare outcomes after mechanical thrombectomy for tandem and single occlusions of the anterior circulation. MATERIALS AND METHODS This prospective study included consecutive patients with acute ischemic stroke of the anterior circulation who had undergone mechanical thrombectomy performed with a stent retriever under conscious sedation within 6h of symptom onset. Data on clinical, imaging and endovascular findings were collected. In cases of tandem occlusion, distal thrombectomy (retrograde approach) was performed first whenever possible. Tandem and single occlusions were compared in terms of functional outcome and mortality at 3 months. RESULTS From May 2010 to April 2012, 42 patients with acute ischemic stroke attributable to MCA and/or ICA occlusion were treated. Eleven patients (26.2%) presented with tandem occlusions and 31 patients (73.8%) had a single anterior circulation occlusion. Baseline characteristics were similar between the two groups. Recanalization status also did not differ significantly (P=0.76), but patients with tandem occlusions had poorer functional outcomes (18.2% vs. 67.7% for single occlusions; P=0.01), a higher mortality rate at 3 months (45.5% vs. 12.9%, respectively; P=0.03) and more symptomatic intracranial hemorrhages at 24h (9.7% vs. 0%, respectively; P=0.01). A high rate of early proximal re-occlusion or severe residual stenosis (66%) was also observed in the tandem group. CONCLUSION Tandem occlusions had poor clinical outcomes after mechanical thrombectomy compared with single occlusions. The retrograde approach (treatment of distal occlusion first) used in patients under conscious sedation may have contributed to these poor outcomes.

How Sustained Is 24-Hour Diffusion-Weighted Imaging Lesion Reversal? : Serial Magnetic Resonance Imaging in a Patient Cohort Thrombolyzed Within 4.5 Hours of Stroke Onset

Background and Purpose— Here, we assessed how sustained is reversal of the acute diffusion lesion (RAD) observed 24 hours after intravenous thrombolysis, and the relationships between RAD fate and early neurological improvement. Methods— We analyzed 155 consecutive patients thrombolyzed intravenously 152 minutes (median) after stroke onset and who underwent 3 MR sessions: 1 before and 2 after treatment (median times from onset, 25.6 and 54.3 hours, respectively). Using voxel-based analysis of diffusion-weighted imaging (DWI)1, DWI2, and DWI3 lesions on coregistered image data sets, we assessed the outcome of RAD voxels (hyperintense on DWI1 but not on DWI2) as transient or sustained on DWI3, and their relationships with early neurological improvement, defined as &Dgr;National Institutes of Health Stroke Scale ≥8 or National Institutes of Health Stroke Scale ⩽1 at 24 hours. Tmax and apparent diffusion coefficient values were compared between sustained and transient RAD voxels. Results— The median (interquartile range) baseline National Institutes of Health Stroke Scale and DWI1 lesion volume were 11 (7–18) mL and 15.6 (6.0–50.9) mL, respectively. The median (interquartile range) RAD volume on DWI2 was 2.8 (1.1–6.6) mL, of which 70% was sustained on DWI3. Sixteen (10.3%) patients had sustained RAD ≥10 mL. As compared with transient RAD voxels, sustained RAD voxels had nonsignificantly higher baseline apparent diffusion coefficient values (median [interquartile range], 793 [717–887] versus 777 [705–869]×10−6 mm2·s −1, respectively; P=0.08) and significantly better perfusion (Tmax, mean±SD, 6.3±3.2 versus 7.8±4.0 s; P<0.001). At variance with transient RAD, the volume of sustained RAD was associated with early neurological improvement in multivariate analysis (odds ratio, 1.08; 95% confidence interval, [1.01–1.17], per 1-mL increase; P=0.03). Conclusions— After thrombolysis, over two-thirds of the DWI lesion reversal captured on 24-hour follow-up MR is sustained. Sustained DWI lesion reversal volume is a strong imaging correlate of early neurological improvement.

Imaging Follow-Up of Intracranial Aneurysms Treated by Endovascular Means: Why, When, and How?

Aneurysm treatment is dedicated to prevention of rupture (for unruptured aneurysms) or rebleeding (for ruptured aneurysms). Endovascular embolization has become the first-line treatment for intracranial aneurysms in the majority of cases in many institutions. This minimally invasive approach achieved lower morbidity and mortality rates when compared with surgical management.1–4 However, although successful in improving patient care, its durability has been noted to be its Achilles’ heel since the earliest application of this technology. Indeed, after endovascular treatment (EVT) ≈20% of patients will experience aneurysm or neck reopening after traditional endovascular coiling, necessitating retreatment in about half of them to maintain long-term protection over bleeding.5 Despite this issue, low rates of bleeding have been reported after EVT of ruptured aneurysms, and its clinical superiority over surgery seems to be maintained over time according to the long-term clinical follow-up of the International Subarachnoid Aneurysm Trial (ISAT) cohort.6,7 In the Cerebral Aneurysm Rerupture after Treatment (CARAT) study, the bleeding rate after coil embolization was 0.11% (mean follow-up time, 4.4 years), whereas in the International Subarachnoid Aneurysm Trial, the annual risk of bleeding after coil-treated aneurysms was 0.08%.8 In a large single-center study, the Barrow Ruptured Aneurysm Trial (BRAT), no bleeding was observed after 6 years in the coiling arm, but 4.6% of these patients were retreated.9 Thus, one may question the clinical usefulness of performing imaging follow-up, balancing the small risk of bleeding after EVT with the cost-effectiveness of follow-up. Although the primary end points of these studies were clinical, it is important to note that the majority of EVT patients had imaging follow-up performed at the discretion of the treating physician. For example, in the ISAT trial, 88.2% of the patients in the EVT arm (881 patients) had follow-up angiograms, generally performed 6 …

Endovascular treatment of acute ischemic stroke in France: A nationwide survey

BACKGROUND AND PURPOSE Developments in endovascular treatment have opened new promising prospects for treating acute ischemic stroke. In France, EVT is increasingly used, especially when intravenous thrombolysis is contraindicated or has failed. However, it has not been documented how neurointerventional centers are organized practically for the treatment of AIS. The present survey aims to address this. MATERIALS AND METHODS The centers in France that are authorized to perform EVT for AIS were invited to participate to an electronic survey. The survey was composed of 33 questions, divided into 6 subheadings: (1) general information, (2) imaging modalities, (3) patient selection, (4) anesthesiology, (5) endovascular procedure and (6) imaging follow-up. RESULTS The response rate was high at 93.9%. Neuroradiology centers are organized to perform mechanical thrombectomy around the clock in 80.6% of the institutions. MRI was the most commonly used imaging modality to examine acute stroke, alone in 64.5% or in combination with CT in 22.6%. The median number of neurointerventionalists was 3 per center and the median number of procedures performed in 2012 was 925. Since the medical treatment is complex, an anesthesiologist is often required during the procedure (87.1%). Technical issues are also developed in the manuscript. CONCLUSIONS This survey shows that French neuroradiology departments have made important efforts to implement EVT of AIS with a high quality of care for the patients; the majority of the centers used MRI to evaluate the disease and anesthesiologists are involved in order to optimize medical care during EVT.

Parenchymal FLAIR hyperintensity before thrombolysis is a prognostic factor of ischemic stroke outcome at 3 Tesla

BACKGROUND The goal of the present study was to determine whether the presence or absence of parenchymal FLAIR hyperintensity alone, before thrombolysis, might be a predictive factor of ischemic stroke outcomes after the acute phase of stroke and at 3 months. MATERIALS AND METHODS We retrospectively included 84 patients with an ischemic stroke between November 2007 and March 2012, who underwent 3T MRI, were treated by thrombolysis, and had medical follow-up at 3 months. Two readers analyzed parenchymal FLAIR visibility. Logistic regressions were performed for NIHSS difference (NIHSS at admission - NIHSS at the end of hospitalization) and for 3 months modified Ranking Score (mRS). Predictive values of positive parenchymal FLAIR for identifying poor outcome at discharge and at 3 months were estimated. RESULTS Parenchymal FLAIR positivity was not predictive of NIHSS difference but it predicted poor outcome at 3 months (sensitivity: 0.49 [0.37-0.60], specificity: 0.69 [0.46-0.91], positive predictive value: 0.87 [0.76-0.98] and negative predictive value: 0.24 [0.12-0.36]). CONCLUSIONS At 3 Tesla, the presence of a parenchymal hyperintense FLAIR signal before thrombolysis is predictive of a poor clinical outcome at 3 months.

Treatment of recurrent aneurysms using the Woven EndoBridge (WEB): anatomical and clinical results

Background The safety and efficacy of the Woven EndoBridge (WEB) for the treatment of naïve intracranial aneurysms has been confirmed. Purpose To analyze the safety and efficacy of the WEB in the treatment of recurrent aneurysms. Methods Anatomical and clinical results in consecutive patients with a recurrent aneurysm, who were treated using the WEB device in two French neurointerventional centers, were evaluated. Results Seventeen patients with 17 aneurysms were included. Treatment was feasible in 16 patients. In seven patients (41.2%), ancillary devices were used. Permanent morbidity due to a thromboembolic complication occurred in one patient (5.9%). There was no mortality. Follow-up angiographic studies were available for 15 patients after a mean of 12.1±6.1 months. Rates of complete occlusion, neck remnant, and aneurysm remnant were 33.3%, 40.0%, and 26.7%, respectively. Conclusions Treatment of recurrent aneurysms using the WEB device may be reasonably safe and effective.

Mechanical thrombectomy "as a rescue treatment" of thromboembolic complications during endovascular treatment of intracranial aneurysms.

Acute thromboembolic periprocedural events during endovascular intracranial aneurysm treatment are mostly treated with intravenous or intra-arterial pharmacological thrombolysis. The present report describes a case of mechanical thrombectomy as a rescue treatment that may be an acceptable alternative to the current strategies. The feasibility and safety of stent retrievers in such a clinical indication are also discussed.

Outcome After Reperfusion Therapies in Patients With Large Baseline Diffusion-Weighted Imaging Stroke Lesions: A THRACE Trial (Mechanical Thrombectomy After Intravenous Alteplase Versus Alteplase Alone After Stroke) Subgroup Analysis

Background and Purpose— Stroke patients with large diffusion-weighted imaging (DWI) volumes are often excluded from reperfusion because of reckoned futility. In those with DWIvolume >70 mL, included in the THRACE trial (Mechanical Thrombectomy After Intravenous Alteplase Versus Alteplase Alone After Stroke), we report the associations between baseline parameters and outcome. Methods— We examined 304 patients with anterior circulation stroke and pretreatment magnetic resonance imaging. Variables were extracted from the THRACE database, and DWI volumes were measured semiautomatically. Results— Among 53 patients with DWIvolume >70 mL, 12 had favorable outcome (modified Rankin Scale score, ⩽2) at 3 months; they had less coronary disease (0/12 versus 12/38; P=0.046) and less history of smoking (1/10 versus 12/31; P=0.013) than patients with modified Rankin Scale score >2. None of the 8 patients >75 years of age reached modified Rankin Scale score ⩽2. Favorable outcome occurred in 12 of 37 M1-occluded patients but in 0 of 16 internal carotid-T/L–occluded patients (P=0.010). Favorable outcome was more frequent (6/13) when DWI lesion was limited to the superficial middle cerebral artery territory than when it extended to the deep middle cerebral artery territory (6/40; P=0.050). Conclusions— Stroke patients with DWI lesion >70 mL may benefit from reperfusion therapy, especially those with isolated M1 occlusion or ischemia restricted to the superficial middle cerebral artery territory. The benefit of treatment seems questionable for patients with carotid occlusion or lesion extending to the deep middle cerebral artery territory.