Vessel Shrinkage and Stroke Recurrence in Intracranial Atherosclerotic Stenosis Under Intensive Lipid-Lowering Therapy

BACKGROUND: Little is known about the dynamic process of the outer-wall boundary during intensive lipid-lowering therapy in patients with intracranial atherosclerotic stenosis and its clinical implications. METHODS: We analyzed patients with first-ever acute ischemic stroke attributed to intracranial atherosclerotic stenosis who received intensive lipid-lowering therapy with high-dose statins or PCSK9i (proprotein convertase subtilisin/kexin type 9 inhibitor). Data were obtained from a multicenter cohort study at 15 hospitals across China and our institutional database in Beijing, China. All patients underwent 3-dimensional T1-weighted high-resolution magnetic resonance vessel wall imaging at baseline and after a >6-month follow-up period. Outer-wall boundary area changes were classified as expansion (>10% increase), shrinkage (>10% decrease), or quiescence (≤10% change). The association between these changes and time to recurrent ipsilateral stroke was assessed. The Kaplan-Meier method and the Cox proportional hazards model were used. RESULTS: Among the 137 patients, 50 (36.5%) exhibited expansion, 40 (29.2%) shrinkage, and 47 (34.3%) quiescence of the outer-wall boundary area. Among these 3 groups, plaque burden decreased significantly between the index imaging and follow-up (all P ≤ 0 .02). Lumen area increased significantly in patients with expansion ( P <0.001) and quiescence ( P =0.01) but not in those with shrinkage of the outer-wall boundary area ( P =0.34). Patients with shrinkage of the outer-wall boundary area had a significantly increased risk of recurrent ipsilateral stroke (hazard ratio, 2.95 [95% CI, 1.02–8.55]; P =0.046) compared with patients without such shrinkage. In multivariable Cox regression analysis, shrinkage of the outer-wall boundary area was associated with recurrent ipsilateral stroke compared with non-shrinkage after adjusting for potential confounders (hazard ratio, 4.21 [95% CI, 1.14–15.58]; P =0.031). CONCLUSIONS: Outer-wall boundary area changes vary among patients with intracranial atherosclerotic stenosis under intensive lipid-lowering therapy. Shrinkage of the outer-wall boundary area is significantly associated with a higher risk of stroke recurrence.