Aspiration Thrombectomy vs. Intravenous Alteplase
What is the potential benefit of aspiration thrombectomy for large vessel occlusion stroke patients compared with intravenous alteplase alone?
THERAPY (The Randomized, Concurrent Controlled Trial to Assess the Penumbra System’s Safety and Effectiveness in the Treatment of Acute Stroke) was an international, multicenter, prospective, randomized (1:1), open-label, blinded endpoint evaluation, concurrent controlled clinical trial of aspiration thrombectomy after intravenous alteplase (IAT) administration compared with intravenous alteplase alone in patients with large vessel ischemic stroke because of a thrombus length of ≥8 mm. The primary efficacy endpoint was the percent of patients achieving independence at 90 days (modified Rankin Scale score, 0–2; intention-to-treat analysis). The primary safety endpoint was the rate of severe adverse events by 90 days (as-treated analysis). Patients were randomized 1:1 across 36 centers in two countries (United States and Germany).
Enrollment was halted after 108 (55 IAT and 53 intravenous) patients (of 692 planned) because of external evidence of the added benefit of endovascular therapy to intravenous alteplase alone. Functional independence was achieved in 38% IAT and 30% intravenous intention-to-treat groups (p = 0.52). Intention-to-treat ordinal modified Rankin Scale odds ratio was 1.76 (95% confidence interval, 0.86–3.59; p = 0.12) in favor of IAT. Secondary efficacy analyses all demonstrated a consistent direction of effect toward benefit of IAT. No differences in symptomatic intracranial hemorrhage rates (9.3% IAT vs. 9.7% intravenous, p = 1.0) or 90-day mortality (IAT: 12% vs. intravenous: 23.9%, p = 0.18) were observed.
The authors concluded that it is possible that an alternate method of thrombectomy, primary aspiration, will benefit selected stroke patients harboring large vessel occlusions.
This study sought to establish the benefit of aspiration thrombectomy in conjunction with intravenous alteplase when compared with intravenous alteplase alone in patients with a large anterior circulation proximal clot burden, but it was halted early based on external evidence demonstrating the efficacy of thrombectomy. Consequently, the trial was not powered to meet its predefined endpoints. However, it did demonstrate a direction of effect toward benefit with both internal and external consistencies. It is possible that an alternate method of thrombectomy, primary aspiration, may benefit selected patients harboring large vessel occlusions. Additional studies on this topic are indicated.
Keywords: Embolectomy, Graft Occlusion, Vascular, Intention to Treat Analysis, Intracranial Hemorrhages, Secondary Prevention, Stroke, Thrombectomy, Thrombosis, Tissue Plasminogen Activator, Vascular Diseases
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