RT Journal Article SR Electronic T1 Aetiology of extracranial carotid free-floating thrombus in a prospective multicentre cohort JF Stroke and Vascular Neurology JO Stroke Vasc Neurol FD BMJ Publishing Group Ltd SP svn-2022-001639 DO 10.1136/svn-2022-001639 A1 Dar Dowlatshahi A1 Cheemun Lum A1 Bijoy K Menon A1 Aditya Bharatha A1 Prasham Dave A1 Paulo Puac-Polanco A1 Dylan Blacquiere A1 Grant Stotts A1 Michel Shamy A1 Franco Momoli A1 Rebecca Thornhill A1 Ronda Lun A1 Carlos Torres YR 2022 UL http://svn.bmj.com/content/early/2022/11/10/svn-2022-001639.abstract AB Background Carotid free-floating thrombi (FFT) in patients with acute transient ischaemic attack (TIA)/stroke have a high risk of early recurrent stroke. Management depends on aetiology, which can include local plaque rupture, dissection, coagulopathy, malignancy and cardioembolism. Our objectives were to classify the underlying aetiology of FFT and to estimate the proportion of patients with underlying stenosis requiring revascularisation.Methods We prospectively enrolled consecutive patients presenting to three comprehensive stroke centres with acute TIA/stroke and ipsilateral internal carotid artery FFT. The aetiology of FFT was classified as: carotid atherosclerotic disease, carotid dissection, cardioembolism, both carotid atherosclerosis and cardioembolism, or embolic stroke of uncertain source (ESUS). Patients with carotid atherosclerosis were further subclassified as having ≥50% or <50% stenosis.Results We enrolled 83 patients with confirmed FFT. Aetiological assessments revealed 66/83 (79.5%) had carotid atherosclerotic plaque, 4/83 (4.8%) had a carotid dissection, 10/83 (12%) had both atrial fibrillation and carotid atherosclerotic plaque and 3/83 (3.6%) were classified as ESUS. Of the 76 patients with atherosclerotic plaque (including those with atrial fibrillation), 40 (52.6%) had ≥50% ipsilateral stenosis.Conclusions The majority of symptomatic carotid artery FFT are likely caused by local plaque rupture, more than half of which are associated with moderate to severe carotid stenosis requiring revascularisation. However, a significant number of FFTs are caused by non-atherosclerotic mechanisms warranting additional investigations.Data are available on reasonable request.