Trends and Progress in Neuroendovascular Treatment in Japan: Japanese Registry of Neuroendovascular Therapy (JR-NET) 4. Main Report.

We reported the main results of the Japanese Registry of Neuroendovascular Therapy (JR-NET) 4, a nationwide surveillance of therapy (NET) in Japan from January 2015 to December 2019. JR-NET 4 registered consecutive patients who underwent NETs by Japan Society of Neuroendovascular Therapy (JSNET) -certified specialists. The primary endpoint was functional independence (mRS score of 0-2) at 30 days post-NET, with secondary endpoints focusing on technical success and major adverse events within 30 days.A total of 63,230 patients and 60,354 NET procedures from 166 participating centers were analyzed. During the study period, NET cases have consistently increased, with an increase in the proportion of elderly patients. A significant trend shift was observed in the distribution of NET procedures, with endovascular treatment for acute ischemic stroke that showed a dramatic increase in 5 years. This trend aligns with key randomized clinical trials from 2015 that presented the efficacy of this treatment. Clinical outcomes at 30 days posttreatment revealed that endovascular treatment for acute ischemic stroke and other NETs maintained safety and effectiveness despite varying prevalence of functional independence between target diseases. The study also observed a steady increase in emergency treatment cases, reflecting the increase in acute ischemic stroke, a time-sensitive medical condition.This comprehensive surveillance highlights the trend of NET practices in Japan, driven by clinical evidence and advancements in treatment devices. Although these findings were specific to Japan, they offer valuable insights into the broader trends in NETs and acute stroke care.