Abstract
Objective: Mechanical thrombectomy is a newly available endovascular treatment for acute stroke in Japan, as MERCI Retriever was approved in 2010. We evaluated initial experience of Merci Retriever mechanical thrombectomy in Japanese top centers.
Method: Fifteen of 19 centers, which experienced 4 cases or more of MERCI Retriever mechanical thrombectomy since approval of MERCI Retriever, contributed to this study. This series was equivalent to 42.0% of whole experience in Japan during the initial 8 months. Baseline, procedure and clinical results variables were retrospectively recorded. Outcome was categorized as Good (modified Rankin scale 0 to 2), Fair (3 to 4), and Poor (5 to 6), and analyzed by each variable and successful recanalization (TICI scale 2A or better 2B or better).
Result: One hundred and ten patients received Merci Retriever mechanical thrombectomy in this study. Mean age was 71.8 years, number of males was 67.2%, and median time from onset to admission was 95 minutes. Baseline median NIHSS was 19, and site of occluded artery was ICA 40.3%, MCA 49.5%, and VABA 9.2%. Mean number of the device used in one treatment was 1.3, and median number of attempts per one target vessel was 2. Treatment resulted in successful recanalization in 74.6% of TICI grade 2A and or better, 48.3% of TICI grade 2B and or better, with adjunctive endovascular technique in 56.7%. Overall, Good clinical outcomes obtained in 28.2%, Fair outcomes in 40.0%, and Poor outcomes in 31.8%. Mortality rate was 10.9%. Intracerebral hemorrhage occurred in 31.6%, while symptomatic hemorrhage occurred only in 2.6%. Clinically significant procedural complication did not occur. Hemorrhage and complications were less than previous reports. Factors significantly related to good outcome were successful recanalization, younger age, low NIHSS score at admission, and high ASPECTS-DWI score before treatment. These results are compatible with previous report of mechanical thrombectomy using MERCI Retriever.
Conclusion: A high rate of successful vessel recanalization and acceptable clinical results with low rate of complications were obtained in initial experience of Mechanical thrombectomy using Merci Retriever in Japan top centers. Contraindicated or failed patients with intravenous rtPA therapy recommended to treat with Merci Retriever mechanical thrombectomy.
