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Endovascular Treatment for Acute Ischemic Stroke
Study Question: Is endovascular treatment (ET) more effective than IV t-PA for treatment of AIS?
Study Description: This multi-center, open-treatment trial randomized adult patients to ET or IV t-PA. Patients were eligible if time of symptom onset could be defined prior to treatment with IV t-PA or ET (within 4.5 or 6 hours, respectively). ET pharmacologic thrombosis utilized catheter-directed t-PA dosed 0.9 mg/kg (maximum 90 mg) infused over 1 hour. t-PA was stopped if recanalization was achieved prior to reaching maximum dose. Mechanical thrombolysis was at the discretion of the interventionalist. IV t-PA was dosed according to current European labeling. Disability-free survival at 90 days was the primary outcome, defined as a modified Rankin score of 0 (no symptoms) or 1 (no clinically significant disability despite symptoms). A 15% absolute difference in the primary outcome was expected between groups based on a pilot phase of the study.
Results: A total of 362 patients were randomized (181 in each group). ET was completed in 165 patients, and 109 of these patients received local t-PA infusion. IV t-PA patients received a median dose of 66 mg (IQR 59-72). For the primary outcome, 55 of 181 patients (30.4%) in the ET group and 63 of 181 patients (34.8%) in the IV t-PA group survived without disability, with an absolute difference of -4.4% (95% CI -14.1 to 5.2). No differences in 90-day mortality were observed (P = 0.22).
Conclusion(s): ET is not superior to IV t-PA in improving functional outcomes or survival in treatment of AIS.
Perspective: Whereas the previous study by Broderick at all assessed the effects of combining therapies, this first clinical trial to directly compare each therapy, ET and IV t-PA, alone for treatment of AIS. The magnitude of difference between the two groups in primary outcome was much less than the expected difference, 15% – a number that had been calculated from a pilot study – suggesting that the sample size calculation was inadequate and the study underpowered. Additional information that might have been of interest but was not reported was stratification by time of administration (e.g., < 3 vs. 3 to 4.5 hours).