Medicare can convene a standing committee of experts called the MedCAC - Medicare Coverage Advisory Committee. The roster has about 100 members and about 8 are flown in for any particular meeting.
In the Federal Register, CMS announces a MedCAC on "cerebro-vascular disease" on September 22. Within the next days, CMS will post more detail about the agenda such as a list of "key questions" for the public to comment on and for the panelists to discuss. The agenda will appear at some point on the "Index of Meetings" which can be accessed via the MedCAC home page here.
Find the CMS meeting announcement here. 86 Fed Reg 41040-42, July 30, 2021.
While CMS didn't provide details beyond the generic topic "cerebrovascular" yet, my guess is, this is related to the perpetually revised NCD on cerebrovascular stents.