The MERCI trial was a prospective single-arm, multicenter trial designed to test the safety and efficacy of the MERCI clot retrieval device to restore the patency of intracranial arteries in the first 8 hours of an acute stroke. All patients were ineligible for IV rt-PA. The occlusion sites were the intracranial vertebral artery, basilar artery, ICA, ICA terminus, or proximal MCA branches (M1 or M2). Primary outcomes were of recanalization and safety, and secondary outcomes were neurological outcomes at 90 days in recanalized versus non-recanalized patients. TIMI 2 or 3 recanalization was achieved in 46% (69/151) of patients in the intention-to-treat analysis and in 48% (68/141) of patients in whom the device was deployed. This rate is significantly higher than that expected using the control arm of the PROACT-II trial (18%) as a historical control (p < 0.0001). After adjunctive therapy (IA rt-PA/UK, angioplasty, snare), the rate of recanalization increased to 60.3%. Clinically significant procedural complications occurred in 10 of 141 (7.1%) patients. Symptomatic ICH was observed in 11 of 141 (7.8%) patients. Good neurological outcomes (mRS < 2) at 90 days were more frequent (46% vs. 10%; relative risk (RR) 4.4) and mortality was less (32% vs. 54%; RR 0.59) with successful compared with unsuccessful recanalization.13
The Multi-MERCI trial was an international multicenter, single-arm trial with three objectives: to gain greater experience with the first-generation MERCI retrieval device (X5 and X6) in patients ineligible for IV rt-PA; to explore the safety and technical efficacy of the MERCI retriever in patients treated with IV rt-PA who failed to recanalize; and to collect safety and technical efficacy data on a second-generation MERCI retrieval device (L5). The primary outcome was vascular reca-nalization and safety. One hundred and eleven patients received the thrombectomy procedure. Mean age was 66.2 ± 17.0 years, and baseline NIHSS score was 19 ± 6.3. Thirty patients (27%) received IV rt-PA before intervention. Treatment with the retriever alone resulted in successful (TIMI 2 or 3) recanalization in 60 of 111 (54%) treatable vessels and in 77 of 111 (69%) after adjunctive therapy (IA rt-PA, mechanical). Symptomatic ICH occurred in 10 of 111 (9.0%) patients: 2 of 30 (6.7%) patients pretreated with IV rt-PA and 8 of 81 (9.9%) without IV rt-PA (p > 0.99). Clinically significant procedural complications occurred in 5 of 111 (4.5%) patients. The authors concluded that mechanical thrombectomy after IV rt-PA 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 strokes in patients who either are ineligible for IV rt-PA or have failed to recanalize with IV rt-PA.39
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