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Free Floating Thrombus

Summary

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  • Free floating thrombus (FFT) is a rare but potentially life-threatening condition characterised by a mobile thrombus in the cardiovascular system, typically attached to a vessel wall by a thin stalk
  • FFTs are associated with high risk of embolization and subsequent ischaemic events
  • Prompt diagnosis and treatment are crucial to prevent serious complications1

Pathophysiology

  • An elongated thrombus attached to the vessel wall by a narrow stalk, with mobile intraluminal extension — a source of artery-to-artery embolic stroke
  • In the neck it usually arises from a ruptured carotid plaque or a dissection; risk factors include atherosclerosis, hypercoagulable states and malignancy

Demographics

  • Incidence is not well-established due to rarity of the condition
  • More common in elderly patients
  • Higher prevalence in patients with:
    • Cardiovascular disease
    • History of thromboembolism
    • Atrial fibrillation

Diagnosis

  • Often an incidental finding on imaging studies
  • Clinical presentation may include:
    • Symptoms of embolization (e.g., stroke, limb ischaemia)
    • Asymptomatic in some cases
  • Diagnostic criteria:
    • Mobile thrombus
    • Thin stalk attachment to vessel wall
    • Independent motion from surrounding structures

Imaging

  • CTA is the mainstay: an intraluminal filling defect surrounded by contrast (the thrombus is separate from the wall except at its stalk), typically at or just above the carotid bifurcation
  • The mobile, non-occlusive nature distinguishes it from fixed plaque; ultrasound may show the thrombus moving with the cardiac cycle

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  • 60-year-old patient with left sided weakness and inattention.
  • CTA showed acute thrombus arising from plaque in the right ICA.
  • The filling defect extending distally within the lumen of the vessel was consistent with free floating thrombus.

Treatment

  • Anticoagulation is usually first-line; carotid endarterectomy/stenting or thrombectomy for recurrent embolism

Differential diagnosis

Imaging differential Differentiating feature
Atherosclerotic plaque Fixed, calcified, wall-adherent lesion without a mobile intraluminal component
Carotid dissection Crescentic mural haematoma (T1-bright on fat-sat) with a tapered lumen
Carotid web Thin shelf on the posterior bulb wall, not a mobile luminal filling defect
Occlusive thrombus Complete filling defect with no surrounding contrast

  1. Camerotte et al. Efficacy and safety of anticoagulant and antiplatelet therapies in the medical management of carotid free-floating thrombus: A systematic review. 2024. Interventional neuroradiology : journal of peritherapeutic neuroradiology, surgical procedures and related neurosciences - Open in new tab. ↩