Background: Knowledge regarding the influence of arterial remodeling patterns on plaque characteristics and postoperative outcomes in patients with severe basilar artery (BA) stenosis after endovascular treatment is lacking. The purpose of this study was to investigate plaque characteristics, remodeling patterns, and perioperative outcomes in patients with severe BA stenosis. Methods: A prospective cohort study was conducted on symptomatic patients with severe BA stenosis who underwent high-resolution MRI before endovascular treatment. The remodeling index, plaque burden, and area of stenosis were evaluated for each plaque. Based on the remodeling index calculated by high-resolution MRI, remodeling patterns were classified as negative remodeling (NR) or non-negative remodeling (non-NR). Baseline demographics, plaque features, and treatment characteristics were compared between the NR and non-NR groups. Correlations between the remodeling index, plaque burden, and stenosis severity were also examined. Results: In total, 140 eligible patients were included and analyzed, including 91 non-NR cases and 49 NR cases. A strong correlation existed between the remodeling index and plaque burden (r=0.973, P<0.001), and a marginal correlation was observed between the remodeling index and degree of stenosis by area (r=-0.261, P=0.0019). There was no significant difference between the two groups in terms of perioperative complications related to ischemic events and new ischemic cerebral lesions (NICLs). Conclusions: Under the current submaximal angioplasty and/or stenting treatment paradigms, remodeling patterns may not influence the outcome of ischemic events and NICLs. However, the remodeling index is strongly associated with plaque burden, which may provide insight for the evaluation of severe BA stenosis. Further research is warranted.