Safety of mechanical thrombectomy and intravenous tissue plasminogen activator in acute ischemic stroke. Results of the multi Mechanical Embolus Removal in Cerebral Ischemia (MERCI) trial, part I

Abstract

Background: The MERCI (Mechanical Embolus Removal in Cerebral Ischemia) trial reported efficacy of the Merci Retriever for opening intracranial vessels in patients ineligible for intravenous (IV) tissue plasminogen activator (tPA). Patients who receive IV tPA but do not recanalize may also benefit from thrombectomy, but the revascularization efficacy and safety of this strategy has not been reported.

Methods: Multi MERCI is an ongoing international, multicenter, prospective, single-arm trial of patients with large vessel stroke treated within 8 hours of symptom onset. Patients were enrolled who had received IV tPA but did not recanalize or who were ineligible for IV tPA. Primary outcome was vascular recanalization (Thrombolysis in Myocardial Infarction [TIMI] score II/III) and safety.

Results: One hundred eleven patients received the thrombectomy procedure. Mean age +/- SD was 66.2 +/- 17.0 years, and baseline National Institutes of Health Stroke Scale (NIHSS) score was 19 +/- 6.3. Thirty patients (27%) received IV tPA before intervention. Treatment with the Retriever alone resulted in successful recanalization in 60 of 111 (54%) treatable vessels and in 77 of 111 (69%) after adjunctive therapy (IA tPA, mechanical). Symptomatic intracranial hemorrhage (ICH) occurred in 10 of 111 (9.0%). Clinically significant procedural complications occurred in 5 of 111 (4.5%) patients. The symptomatic ICH rate was 2 of 30 (6.7%) in patients pretreated with IV tPA and 8 of 81 (9.9%) in those without (P > .99).

Conclusions: Mechanical thrombectomy after IV tPA seems as safe as mechanical thrombectomy alone. Mechanical thrombectomy with both first- and second-generation Merci devices is efficacious in opening intracranial vessels during acute ischemic stroke in patients who are either ineligible for IV fibrinolytic therapy or have failed IV fibrinolytic therapy.

Figures

Fig 1.

Illustration of the L5 thrombectomy device removing thrombus. The L5 device is a helix of flexible nitinol wire with an arcade of filaments secured to the loops of the helix. This differs from the X5 and X6 Merci Retrievers by having filaments and no taper to the coils. Within 8 hours of acute ischemic stroke, the balloon guide catheter is placed via femoral artery into the proximal internal carotid or vertebral artery. The blue microcatheter is advanced through the balloon guide catheter and placed through the occlusion using a microguidewire. The guidewire is then exchanged for the Retriever, which is advanced distal to the clot and several loops are deployed (A). The device is further deployed so as to fully ensnare the clot (B). Then, the proximal balloon of the guide is inflated to prevent distal embolization, some torquing maneuvers are applied, and the microcatheter and Retriever are withdrawn together to retrieve the clot (C).

Fig 2.

Multi MERCI patient flow and primary outcomes. Recanalization is from device alone; final recanalization is after Retriever and any adjuvant therapy. Patients with symptomatic intracranial hemorrhage (ICH), and procedural complications may overlap.