Endovascular Treatment of Acute Stroke with Major Vessel Occlusion before Approval of Mechanical Thrombectomy Devices in Japan: Japanese Registry of Neuroendovascular Therapy (JR-NET) and JR-NET 2

The aim of this study was to clarify the general status and historical transition of endovascular therapy (EVT) of acute stroke with major vessel occlusion before approval of mechanical thrombectomy devices in Japan from January 2005 to December 2009. We extracted 1,409 acute ischemic stroke patients receiving EVT (513 women, 69.8±11.8 years) from two nationwide registry studies, the Japanese Registry of Neuroendovascular Therapy (JR-NET) and JR-NET 2. The median baseline National Institutes of Health Stroke Scale (NIHSS) score was 18, and 81.3% of the patients received EVT within 6 hours after symptom onset. The culprit occluded arteries were the internal carotid artery (ICA) in 21.2%, middle cerebral artery (MCA) in 53.0%, and basilar artery (BA) in 20.6%. Intravenous thrombolysis was administered to 6.7% of the patients, and EVT mainly consisted of intra-arterial thrombolysis and percutaneous balloon angioplasty/balloon clot disruption. The final recanalization rate was 82.5%, and the clinical outcome was favorable in 35.8% and fatal in 11.6% at 30 days after onset or at discharge. There was no significant change in neurological severity at baseline throughout the study period, but the onset-to-treatment time became longer and the proportion of ICA or BA occlusion increased annually. Although the final recanalization rate was similar throughout the study period, the incidence of a favorable outcome tended to decreased annually from 41.0% to 29.0%. These results could be considered as baseline data that can be used to validate the beneficial effects of novel EVT devices in Japan.