Update in Neurology

Stroke

Mechanical Embolus Retrieval System Expanded the Window of Treatment Time in Acute Ischemic Stroke

The Mechanical Embolus Removal in Cerebral Ischemia Retrieval System comprises a microcatheter and a retriever system consisting of a tapered wire with 5 helical loops of decreasing diameter. The catheter is guided into the occluded vessel and passed through the arterial thrombus. The outer catheter is retracted back through the thrombus, leaving the proximal loops of the retrieval system to be deployed and torqued within the thrombus. The ensnared thrombus is then removed.

In this phase I study, the investigators enrolled 30 adult patients in 7 U.S. centers to evaluate the safety and technical efficacy of embolectomy of the cerebral arteries. A total of 28 patients were treated. Inclusion criteria were 1) an acute stroke with National Institutes of Health Stroke Scale score of 10 or higher, 2) presentation between 3 and 8 hours of symptom without contraindications to intravenous thrombolysis, 3) presentation within 3 hours of symptom onset with contraindications to intravenous thrombolysis, 4) angiographic evidence of occlusion of a major cerebral artery, and 5) no large hypodensity on computed tomography. Recanalization of the occluded artery occurred in 12 of 28 (43%) patients. The procedure was well tolerated, and patients with recanalized arteries had better 30-day outcomes (9 of 18) than those whose arteries did not recanalize (0 of 10).

The U.S. Food and Drug Administration approved the Concentric Merci Retrieval System (Concentric Medical, Inc., Mountain View, California) in August 2004 (1). Although this embolus retrieval system requires significant technical expertise and questions remain about how it compares with intra-arterial …