Stroke Intervention: Catheter-Based Therapy for Acute Ischemic Stroke
The following are 10 points to remember about this white paper on stroke intervention:
1. Stroke is common, with nearly 750,000 patients suffering a stroke annually in the United States. It is the leading cause of adult disability, and the annual direct and indirect cost of stroke exceeded $62 billion in 2007.
2. Over 80% of strokes are ischemic in nature, and most are secondary to cardioembolism or atherothromboembolism.
3. The major goal in acute ischemic stroke is timely reperfusion, albeit with a narrow time window and a higher risk of major complications compared with acute myocardial infarction.
4. Thrombolytic therapy in the form of intravenous (IV) tissue plasminogen activator (tPA) is most effective when administered to patients with no evidence of bleeding on CT imaging, and who present within 3 hours (up to 4.5 hours) of symptom onset with moderate clinical deficit (National Institutes of Health Stroke Scale [NIHSS] score of 4-12).
5. IV heparin should be avoided in patients with stroke. Hemorrhagic transformation has been reported in 8% of patients with acute cardioembolic stroke within the first week of stroke when treated with IV heparin, while the risk of second stroke is 2%.
6. Catheter-based therapy should be considered for patients who present outside the <3- to 4.5-hour window. Intra-arterial thrombolysis may be beneficial up to 6 hours after symptom onset. The PROACT I and II trials were small studies that demonstrated better neurological recovery at the cost of increased intracranial bleeding in patients treated with intra-arterial pro-urokinase. There is no Food and Drug Administration approved thrombolytic drug for intra-arterial thrombolysis for stroke.
7. Two thrombectomy catheters are approved for use in stroke, but neither has been evaluated in randomized controlled trials. The Merci retrieval system was used to treat 151 patients presenting within 8 hours of stroke (mean NIHSS score of 20) and large-vessel occlusion on angiography. Recanalization was achieved in 48%, and symptomatic intracranial bleeding occurred in 7.8%. Even among patients with successful recanalization, mortality has ranged from 25-30%.
8. Similar results were seen with the Penumbra device that was tested in a single-arm study. Recannalization was achieved in 81% of patients with intracranial bleeding in 28%. Good functional outcome was obtained in 25%, and all-cause mortality was 32%.
9. Angioplasty and stenting have been used for acute stroke, but large series or randomized data are lacking. In small series describing experience at selected centers, good outcome has been reported in select patients, although intracranial bleeding remains a serious limitation.
10. The acute treatment of stroke remains a challenge, with less than 3% of patients being treated with IV tPA, and catheter-based therapy being used in <1%. About half of the patients with acute stroke arrive in an emergency room within 3 hours of symptom onset, whereas approximately two thirds arrive within 6 hours. The remarkably low use of reperfusion therapy for stroke invokes the need for collaborative community-wide efforts to bridge this gap and improve the care of patients with stroke.
Keywords: Thrombolytic Therapy, Myocardial Infarction, Stroke, United States Food and Drug Administration, Thrombectomy, National Institutes of Health (U.S.), Fibrinolytic Agents, Emergency Service, Hospital, Angioplasty, United States
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