Intracranial atherosclerotic stenosis (ICAS) has been recognized as a common cause of stroke and transient ischemic attack (TIA), particularly in Asian populations [1,2]. Traditionally, a stenosis threshold of ≥ 70 % has been used to define severe intracranial atherosclerotic disease, largely based on landmark trials such as the Warfarin–Aspirin Symptomatic Intracranial Disease (WASID) and Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPR…