Angioscopy Visualized a Residual Free‐Floating Thrombus in Mild Carotid Artery Stenosis Following Acute MCA Occlusion: A Case Report

Carotid free-floating thrombus (CFFT) is a rare yet severe cause of the ischemic stroke. Early identification and appropriate management are crucial to prevent recurrent embolic events. A 76-year-old man experienced sudden left-sided hemiparesis and dysarthria. Magnetic resonance imaging revealed a high-intensity diffusion area in the right frontal and temporal cortices and occlusion of the right middle cerebral artery (MCA). Digital subtraction angiography (DSA) confirmed the right MCA occlusion with suspected CFFT at the internal carotid artery bifurcation. Mechanical thrombectomy with an aspiration catheter achieved successfully recanalized the right MCA. Following conservative antithrombotic therapy, the CFFT had gradually decreased over 3 weeks. Carotid artery stenting was performed to prevent recurrent stroke. The CFFT disappeared on pre-stenting DSA, although angioscopy identified residual mild stenosis with vulnerable plaque that was not initially detected by DSA. This case highlights the importance of multimodal imaging in diagnosing and managing carotid thrombi associated with mild stenosis. Meticulous examination using several different imaging modalities enables identification of the pathology.