Association between Internal Carotid Artery Tortuosity and Hemorrhagic Transformation in Patients with Acute Ischemic...

Introduction: Hemorrhagic transformation is one of the most common complications of acute ischemic stroke. However, the association between hemorrhagic transformation and internal carotid artery (ICA) tortuosity has rarely been investigated. This study investigated the effect of ICA tortuosity on hemorrhagic transformation after acute ischemic stroke.

We conducted a retrospective analysis on stroke patients' data collected from prospective hospital-based stroke registry. The baseline demographics, clinical and radiological variables, including the Fazekas scale, advanced Fazekas scale (grade 0-9), white matter hyperintensity volume, presence of cerebral microbleeds, and hemorrhagic transformation, were compared based on the severity of ICA tortuosity and divided into quartiles (Q1: <25%, Q2+Q3: 25%-75%, and Q4: >75%). ICA tortuosity was examined using in-house vessel analysis software. The primary outcome was hemorrhagic transformation.

A total of 146 patients were analyzed, including 167 ICAs, which were vascular territories with acute cerebral infarction. Among the various risk factors considered, intravenous thrombolysis, endovascular thrombectomy, stroke severity, and ICA tortuosity index were associated with the occurrence of hemorrhagic transformation. In multivariate analysis, ICA tortuosity was also significantly associated with the occurrence of hemorrhagic transformation, while the severity of ICA tortuosity was negatively correlated (Q1: reference, Q2+Q3: 0.27 [0.09-0.84], Q4: 0.14 [0.03-0.70]; p = 0.023 for Q2+Q3, p = 0.016 for Q4).

We identified a paradoxical relationship between ICA tortuosity and hemorrhagic transformation after acute ischemic stroke. Patients with more severe tortuosity experienced fewer hemorrhagic transformations, and vice versa. These findings highlight the potential of ICA tortuosity as a marker for identifying high-risk patients.