By Gauthier Duloquin1, MD & Barbara Casolla2, MD, PhD
1 Department of Neurology – University Hospital of Dijon, France
2 Stroke Unit – University Hospital of Nice, France
Carotid free-floating thrombi (CFFT) are responsible for about 0.4%1 of anterior circulation ischaemic strokes. Although rare, it is a threatening condition that exposes patients to a high risk of ischaemic recurrence, with previous report estimating 11% recurrence risk in the first month2.
Figure 1 : Computed Tomography Angiography of a Carotid free-floating thrombi due to atherosclerotic plaque rupture (blue arrow).
Thrombus formation is often triggered by an underlying arterial lesion, most commonly atherosclerosis and carotid artery dissection (Figure 1). Nevertheless, CFFTs have also been associated with fibromuscular dysplasia, carotid webs and vasculitis3. In this regard, performing high-resolution arterial imaging with Computed Tomography Angiography (CTA) or Magnetic Resonance Angiography (MRA) is recommended by stroke guidelines4. Moreover, many authors suggest assessing the presence of an underlying pro-thrombotic state as part of the diagnostic work-up in these patients5.
To date, little evidence is available on the optimal treatment of these patients and no randomized study has been conducted yet, leading to lack of recommendation for clinical practice. Whether these patients should receive antiplatelet drugs, anticoagulants, or whether these regimes should be combined is still a matter of debate. A literature review published in 20195 on 525 cases did not find any evidence for the benefit of anticoagulant treatment in reducing short-term mortality or risk of recurrent TIA or stroke. However, most studies included in this systematic review were retrospective, with significant allocation biases and unblinded endpoint assessment. Recently, safety of aggressive medical treatments has been reported in case series. For instance, a combining an antiplatelet agent and unfractionated heparin, with a reduced target of activated partial thromboplastin time, i.e. 1.5- 2.0, has been proposed in particularly high risk situation, with a low risk (≈1.8%) of recurrent ischemic event and ≈11.9% of the cases experienced asymptomatic haemorrhagic transformations6. However, the benefit-risk balance of aggressive antithrombotic treatment should always take into account the underlying aetiology and the bleeding risk of the parenchymal ischaemic lesions.
Literature on CFFT is methodologically flawed and we found very few recorded studies underway on this topic7. Unfortunately, considering that this is a rare clinical condition, with underlying heterogeneous aetiologies and individual-level bleeding risk stratification, it is unlikely that we will achieve data from a randomized clinical trial. A multicentre observational register could be of help in identifying patient candidates for aggressive treatment.
- Biller J, Adams HP, Boarini D, Godersky JC, Smoker WR, Kongable G. Intraluminal clot of the carotid artery. A clinical-angiographic correlation of nine patients and literature review. Surg Neurol. 1986;25:467–477.
- Villareal J, Silva J, Eliasziw M, Sharpe B, Fox A, Hachinski V. Prognosis of patients with intraluminal thrombus in the internal carotid artery. Stroke. 1998.:276.
- Bhatti AF, Leon LR, Labropoulos N, et al. Free-floating thrombus of the carotid artery: literature review and case reports. J Vasc Surg. 2007;45:199–205.
- European Stroke Organisation (ESO) Executive Committee, ESO Writing Committee. Guidelines for management of ischaemic stroke and transient ischaemic attack 2008. Cerebrovasc Dis Basel Switz. 2008;25:457–507.
- Fridman S, Lownie SP, Mandzia J. Diagnosis and management of carotid free-floating thrombus: A systematic literature review. Int J Stroke Off J Int Stroke Soc. 2019;14:247–256.
- Singh R-J, Chakraborty D, Dey S, et al. Intraluminal Thrombi in the Cervico-Cephalic Arteries. Stroke. 2019;50:357–364.