The American Heart Hospital Journal


ECASS II definition (OR 2.11, 95% CI 1.29–3.45; p=0.0031). Although thrombolysis is not contraindicated in patients receiving antiplatelet therapy, caution is warranted in those receiving aspirin + clopidogrel.14


Common reasons for not qualifying for tPA are contraindications to systemic exposure to fibrinolytic agents and being outside the time window for treatment. Patients with moderate to severe strokes (NIHSS ≥10) often have persistent major arterial occlusions and poorer outcomes.15


Such patients may qualify for intra-arterial (IA) thrombolytic agents. Criteria for use of these agents include middle cerebral artery (MCA) occlusion, treatment within six hours of stroke onset, and treatment at a stroke center.7


Research is being conducted on the combined use of IV/IA tPA to treat acute ischemic stroke. The Interventional Management of Stroke (IMS) trials achieved higher rates of early, successful reperfusion using IV/IA tPA in patients with moderate to severe strokes (NIHSS ≥10).15


IMS I showed that


The mortality rate for the IMS treatment group (16%, 13/80) was not statistically different from that of the IMS placebo group (24%, 50/211) nor from that of the IV tPA-treated patients of the NINDS trial (21%, 39/182).16


low-dose IV tPA followed by IA tPA via standard microcatheter may be more effective than standard IV tPA for moderate to severe strokes, with a similar safety profile.15,16


IMS


IMS II had a mortality rate of 16% (13/81) and significantly better outcomes than the placebo group in the NINDS standard tPA trial,17


providing support for further


research into combined IV/IA tPA treatment. IMS III aims to determine whether IV/IA tPA is superior to standard IV tPA in subjects with moderate to severe strokes.15


Some large-vessel occlusions may not respond to IV tPA and may require mechanical removal of the clot. The Merci Retrieval System® (Concentric Medical, Inc., Mountain View, CA) is a mechanical clot-removal device for large-vessel occlusions.18–20


It consists of a balloon-guided


microcatheter system that includes a coil-shaped retrieval device.20


The device should be used as


early as possible, but successful results have been reported as late as 36 hours after stroke onset.21


In the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) I trial, patients (n=141) with stroke onset


Winter 2010


The Merci device may be used in addition to IV tPA for occlusions of the proximal MCA/internal carotid artery or the basilar artery.18,19


II had a similar design to IMS I but included the use of the EKOS small-vessel ultrasound infusion system (EKOS Corporation, Bothell, WA), which employs a microcatheter and ultrasonic energy source to facilitate access of the tPA to the thrombus.17


Plans are for this phase II trial to include 120 patients in 30 treatment centers and to allow patients to be treated up to eight hours after stroke onset.23


assist clinicians in identifying and targeting the penumbra, where there is the best chance of ischemia recovery. It is hoped that this will result in better outcomes by identifying patients who have potential for recovery of brain tissue after clot removal.


Another mechanical clot removal system, the Penumbra System® (Penumbra, Inc., Alameda, CA), provides two options for removal of an occlusion. The thrombus may be aspirated using a vacuum connected to a reperfusion catheter. If the thrombus cannot be aspirated, it may be directly removed using a ring attached to the catheter.24


The


vacuum may assist in minimizing or avoiding unwanted embolization during recanalization. Similar to the Merci device, the Penumbra system is used in patients who have either passed the window for IV tPA or are not eligible for or are refractory to IV tPA.24


(n=125), recanalization occurred in 81.6% of patients.24


In the Penumbra pivotal trial At


90 days, the mortality rate was 32.8% (41/125) and the rate of symptomatic ICH was 11.2% (14/125).24


Twenty-five


percent of patients (31/125) had a modified Rankin score ≤2.24


Finally, the Neuroflo™ catheter (CoAxia, Inc., Maple Grove, MN), a device that redirects blood flow to the brain by partially occluding aortic blood flow via a balloon, is


Management of Acute Stroke and Transient Ischemic Attack 93


In another ongoing trial, Merci Retriever and REcanalization of Stroke Clots Using Embolectomy (MR RESCUE), diffusion–perfusion MRI is being used to select candidates for Merci.23


Imaging will


between three and eight hours, or with duration of nought to three hours with a contraindication for IV tPA and with treatable vessels, were treated with the Merci Retrieval System to restore blood flow.22


was observed in 48% (68/141; p<0.0001) of patients.22


90 days, a favorable outcome (modified Rankin score ≤2) was seen in 36.4% of the recanalized patients and in 22% of all Merci-treated patients.22


The Multi MERCI trial uses a family of Merci devices that differ in terms of coil shape. In this ongoing trial, 164 patients with occlusion locations similar to those of the patients in the MERCI trial underwent the procedure.18 Twenty-nine percent of patients failed to recanalize following IV tPA pre-treatment; 55% recanalized following use of the Merci devices.18


At 90 days, the mortality rate


was 34% and the rate of symptomatic ICH was 9.8%.18 More than one-third of patients (36%) had a modified Rankin score ≤2.18


Review


Recanalization At


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