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Patients with a large cerebral artery occlusion and a large clot burden are less likely to benefit from rtPA and are at high risk of a neurologically disabling outcome. More proximal occlusions are also more resistant to thrombolysis, as are those occlusions resulting from clots with less favorable composition.Furthermore, because some patients fail to meet the eligibility criteria for intravenous rtPA, thrombectomy techniques were developed with clot-retrieving devices to improve canalization of the artery and arrest the ischemic stroke. Therefore, as part of the initial imaging evaluation of acute ischemic stroke, noninvasive vascular study, such as CT angiography, should be performed to assess the patient’s candidacy for endovascular intervention.Mechanical thrombectomy (MT) performed with first-generation stent retrievers such as the Merci and Penumbra failed to show an improvement in patient outcomes. However, secondgeneration stent retrievers such as Solitaire and Trevo achieved significantly higher recanalization rates with correspondingly improved outcomes. Five clinical trials with second-generation stent retrieval devices (ESCAPE, EXTEND-IA, MR CLEAN, REVASCAT, and SWIFT PRIME) showed the efficacy of MT when compared with standard medical care in patients with acute ischemic stroke caused by occlusion of the large arteries of the proximal anterior circulation.

Anatomic success with recanalization, functional independence, and major neurologic recovery was significantly better in those patients receiving MT. However, mortality at 90 days, risk of intracranial hemorrhage, and risk of parenchymal hematoma involving greater than 30% of the infarct territory did not differ between the 2 study populations. These data have resulted in a paradigm shift in the early treatment of ischemic stroke; mechanical thrombectomy with secondgeneration stent retrieving devices is now highly recommended in eligible patients. Mechanical thrombectomy should be performed at centers with surgeons skilled in the use of stent-retrieving devices, and initiation of MT should be within 6 hours of stroke onset.

Investigational reperfusion techniques Currently under investigation are other methods of reperfusion, such as intra-arterial thrombolysis (SYNTHESIS expansion trial), use of alternative fibrinolytic agents, combined intravenous and intra-arterial thrombolysis (IMS III trial), stenting, and combined use of fibrinolytics and glycoprotein IIb/IIIa antagonists, but none 125 of these techniques have yet demonstrated improved outcomes.