Emergency Stenting of the Extracranial Internal Carotid Artery in Combination with Anterior Circulation Thrombectomy in Acute Ischemic Stroke: A Retrospective Multicenter Study

Inclusion Criteria

The centers were free to include either all patients since 2007 (before the introduction of stent retrievers for mechanical thrombectomy) or only patients who received a stent retriever and/or direct aspiration treatment.

Eligibility for mechanical thrombectomy was decided at the local institution according to the guidelines of each center. Patients were eligible for concomitant IV thrombolysis according to the guidelines of the German Society of Neurologists. There were no general limitations on procedural timings, age, or baseline NIHSS score. Patients had to present with an angiographically (CTA or DSA) proved high-grade stenosis or occlusion of the ipsilateral ICA and additional large-artery occlusion of the anterior circulation. A high-grade ipsilateral stenosis was thereby defined as a stenosis of ≥70% according to the NASCET criteria. Anterior large-artery occlusions were subdivided into terminal ICA, carotid-T, and MCA occlusions.

Patients were included only if the ipsilateral ICA was stented and the occlusion of the anterior circulation was treated either in an antegrade (stent before thrombectomy) or retrograde (stent after thrombectomy) fashion. There was no limitation on the stent used or on the technique for the intracranial thrombectomy.

All patients were included independent of the administered antiplatelet medication, which was different in all 4 centers.

The antiplatelet regimens were as follows:

Center A: If the patient had no prior medication with dual antiplatelets before the intervention, eptifibatide was continuously infused for 24 hours (after an initial bolus [180 mcg/kg for 2 minutes]) to prevent secondary stent occlusion. Patients were monitored in the intensive care unit postinterventionally. A control CT scan was obtained within 24 hours. After exclusion of a relevant intracranial hemorrhage, the regimen was switched to a secondary prophylaxis of stent occlusion based on a dual antiplatelet therapy: Under continuous IV eptifibatide, patients received a loading dose of 300 mg clopidogrel and 500 mg aspirin. Patients with daily aspirin medication before the intervention did not receive an aspirin loading dose. The administration of eptifibatide was stopped 4 hours after loading with clopidogrel (and aspirin whenever applicable). Patients continued with life-long aspirin (100 mg/day) and additional clopidogrel (75 mg/day) for 8 weeks.

Center B: Patients received an IV bolus of 500 mg aspirin directly before stent placement and, additionally, 375 mg clopidogrel over a nasogastric tube. After exclusion of a relevant intracranial hemorrhage (control CT scan within 24 hours), the dual antiplatelet medication with aspirin (100 mg/day) and clopidogrel (75 mg/day) was continued for 3 months and then switched to a life-long aspirin (100 mg/day) monotherapy.

Center C: All patients who were not on an antiplatelet medication before the treatment received a weight-adapted bolus of tirofiban followed by a continuous IV infusion for 24 hours. After exclusion of a cerebral hemorrhage (CT scan), 500 mg aspirin and 300 mg clopidogrel were given orally or through a nasogastric tube. Aspirin (100 mg/day) and clopidogrel (75 mg/day) were continued for 3 months followed by a life-long antiplatelet monotherapy with either aspirin or clopidogrel.

Center D: Immediately before stent placement, patients received an IV bolus of aspirin (500 mg) and an IV bolus of heparin (5000 IU). Alternatively, tirofiban was used. At the end of the intervention, a flat panel CT scan was performed to rule out intracranial hemorrhage; if so, the patients received a loading dose of clopidogrel (600 mg) orally. Aspirin (100 mg/day) and clopidogrel (75 mg/day) were continued for 3 months and then switched to a life-long aspirin (100 mg/day) monotherapy.

Exclusion Criteria

Any infarction of equal to or more than one-third of the MCA territory or evidence of an intracranial hemorrhage on the initial CT scan led to exclusion. Additionally, all patients without persistent intracranial occlusion after extracranial stent placement were excluded.

Endovascular Procedures

The endovascular procedures have been described in detail previously.^4,5,7,15 None of the centers used a balloon-guide occlusion catheter. In brief, the procedures were the following:

Antegrade approach: A large guide catheter (Neuron MAX 088; Penumbra, Alameda, California; Mach1; Boston Scientific, Natick, Massachusetts; VISTA BRITE TIP; Cordis, Fremont, California) was placed into the distal common carotid artery. A 0.014-inch wire was then carefully navigated through the ICA occlusion up to the petrous portion in conjunction with a microcatheter. A slow and careful contrast injection was then performed to verify passage into the true lumen. Pre-stenting balloon angioplasty was performed whenever necessary with a 3.0- or 3.5-mm monorail balloon. The subsequent MT in the intracranial portions was performed in a usual manner. In case of a biaxial approach with a stent retriever (Trevo variants, Stryker, Kalamazoo, Michigan; Separator 3D, Penumbra; Solitaire AB/FR; Covidien, Irvine, California), the stent was passed with the guiding catheter before retraction of the stent retriever; in a triaxial setting, the stent was passed with the intermediate catheter and the stent retriever was retracted into it to not interfere with the stent. No such precautions were necessary in cases of direct-aspiration-treatment technique without the use of a retriever.

Retrograde approach: Analogously, a large guide catheter was placed in the distal common carotid artery; the proximal ICA stenosis was then passed with a 0.014-inch micro-guidewire followed by an intermediate catheter (054 or 5MAX, Penumbra; DAC, Stryker; Navien, Covidien). The intermediate catheter was positioned as close to the clot as possible, allowing lesional aspiration. We then performed MT using a stent retriever in the usual fashion. After successful revascularization of the occluded intracranial vessel, an exchange microwire was introduced over the intermediate catheter and then exchanged for the stent at the proximal occlusion/stenosis site.

Imaging Evaluation

All imaging data were analyzed at the level of the participating centers by an interventional neuroradiologist; the angiographic results were locally graded according to the TICI score. A successful recanalization was defined as a TICI result of ≥2b.

All postinterventional control CT scans of the patients were screened for intracranial hemorrhages, and all centers reported all parenchymal type 1 (parenchymal hematoma [PH]1: bleeding <30% of the infarcted area with a mild space-occupying effect and parenchymal hematoma) and type 2 (PH2: bleeding of >30% of the infarcted area with a relevant space-occupying effect) hematomas and all sICHs, according to the European Cooperative Acute Stroke Study criteria (any apparently extravascular blood in the brain or within the cranium that was associated with clinical deterioration, as defined by an increase of ≥4 points in the NIHSS score, or that led to death and that was identified as the predominant cause of the neurologic deterioration).¹⁷

Clinical Evaluation

A stroke neurologist assessed all patients clinically on admission (NIHSS) and discharge (NIHSS and mRS) from the stroke center and the rehabilitation unit (follow-up mRS at ∼90 days; range, 70–100 days). In cases with missing follow-up data, the discharge mRS was used instead.¹⁸

Data Analysis and Statistics

The data were collected at each center according the above-mentioned criteria, pooled, and then analyzed at 1 of the 4 centers. Continuous study parameters were compared among patients by either the Welch t test in case of a normal distribution or by the Mann-Whitney U test in case of a non normal distribution. The Fisher exact test was used for categoric variables. All statistical analyses were performed by using GraphPad Prism software, Version 6.1 (GraphPad Software, San Diego, California); the significance level was set at α = .05.