Baseline Occlusion Angiographic Appearance on Mechanical Thrombectomy Suggests Underlying Etiology and Outcome

Background: An in situ thromboocclusion (IST) is defined as an infarct extensively involving all or most of a stenosed arterial territory, which is one major stroke mechanism related to intracranial atherosclerosis (ICAS). We focused on ISTs occurring in major cerebral arteries and analyzed their rate of instant reocclusion during mechanical thrombectomy (MT) compared with non-ISTs. Also, we introduced a treatment strategy of low-dose intra-arterial tirofiban administration to prevent such reocclusion following repeat recanalization, and evaluated its safety and efficacy. Methods: We analyzed 168 consecutive patients treated with MT over a 2-year period from May 2011 to April 2013. During MT, if angiography following a successful recanalization showed stenosis at the occlusion site, we performed additional angiographic runs every 10 min for 30 min after the recanalization. Then, if angiography revealed reocclusion, we performed a repeat recanalization, using the same MT technique but additionally followed by low-dose intra-arterial tirofiban infusion. Time-of-flight MR angiography or CT angiography was performed to confirm any underlying ICAS at the occlusion site 5-7 days after the procedure. The patients who had confirmed underlying ICAS were included in the IST cohort. Results: Of 168 enrolled patients, we excluded 36 who could not be checked for underlying ICAS at the occlusion site for one of the following reasons: recanalization failure (n = 11), rescue stenting after tirofiban failure (n = 5) and lack of follow-up vascular imaging (n = 20). The incidence of IST was 30.3% (40/132). All IST patients were confirmed to have underlying ICAS by follow-up vascular imaging. Instant reocclusion after successful recanalization was significantly more frequent in the IST cohort [26/40 (65%) vs. 3/92 (3.3%); p < 0.001]. Regarding the efficacy of low-dose intra-arterial tirofiban infusion, 85.7% of the reocclusion patients finally achieved a thrombolysis in cerebral infarction score 2/3 recanalization, but in the remaining 14.3% of the cases, the condition was refractory to the procedure and required rescue stenting. There were no cases of symptomatic intracranial hemorrhage following the procedure. Conclusions: In situ thromboocclusion was characterized by a significantly higher chance of instant reocclusion during MT. In such cases, low-dose intra-arterial tirofiban administration may be effective and safe. However, future confirmation by prospective multicenter trials seems necessary.

The importance of underlying atherosclerotic intracranial artery stenosis (ICAS) in hyperacute stroke patients who receive endovascular therapy remains unknown.

In a meta-analysis of individual patient data from 5 randomized controlled trials, endovascular treatment (EVT) mainly using a stent retriever achieved successful recanalization in 71.1% of patients suffering from acute stroke due to anterior circulation large artery occlusion (LAO). However, EVT still failed in 28.9% of LAO cases in those 5 successful trials. Stent retriever failure may occur due to anatomical challenges (e.g., a tortuous arterial tree from the aortic arch to a target occlusion site), a large quantity of clots, tandem occlusion, clot characteristics (fresh versus organized clots), different pathomechanisms (embolic versus non-embolic occlusion), etc. Given that recanalization success is the most important factor in the neurological outcome of acute stroke patients, it is important to seek solutions for such difficult cases. In this review, the basic technique of EVT is briefly summarized and then various difficult cases with diverse conditions are discussed along with suggested solutions.