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Prospective Evaluation of Carotid Free-floating Thrombus

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ClinicalTrials.gov Identifier: NCT02405845
Recruitment Status : Completed
First Posted : April 1, 2015
Last Update Posted : October 14, 2021
The Ottawa Hospital
Information provided by (Responsible Party):
Ottawa Hospital Research Institute

Brief Summary:

Hardened plaque located in the carotid arteries can cause stroke or transient ischemic attack (TIA). This type of plaque is linked to unstable free-floating thrombi (FFT). FFT are blood clots that form in a blood vessel, and are at the highest risk for travelling within the bloodstream and causing strokes. Physicians are able to see this type of plaque with computed tomographic angiography (CTA) but FFT look very similar to stable types of plaque that do not require urgent treatment.

Distinguishing between these plaques is important because it affects the choice and urgency of treatment that patients receive.

The researchers have found a promising visual marker on CTA scans. The goal of this study is to determine if this visual marker seen on CTA scans will help to distinguish FFT plaque from stable plaque.

Condition or disease Intervention/treatment Phase
Stroke Transient Ischemic Attack Radiation: Computed Tomographic Angiogram Not Applicable

Detailed Description:

Atherosclerotic plaques at the origin of the internal carotid artery (ICA) can cause TIA/stroke, and are well-visualized with CT angiography (CTA). Those plaques associated with unstable free-floating thrombi (FFT) are at highest risk for embolization and stroke. Unfortunately, FFT have a similar appearance to stable ulcerated plaques on CTA: both appear as intraluminal filling defects of varying length and morphology. Distinguishing these entities is critical as it affects the choice and urgency of treatment (antithrombotics vs revascularization). Using a retrospective study, we have previously proposed a promising CTA imaging marker to distinguish FFT from stable ulcerated plaque. It is hoped that after the data is collected from this prospective study to one day initiate a multi-centre study.

In our prior research, we proposed a reasonable "gold standard" for FFT diagnosis. We followed patients presenting with circular filling defects on CTA (doughnut signs) suspicious for either FFT or ulcerated plaque with serial CTAs after medical therapy. Those that diminished or resolved with antithrombotic treatment (or those that unfortunately "resolved" by embolizing distally) were presumed to be "true FFT" in contrast to those that remained unchanged. We then assessed the performance of a variety of imaging parameters to differentiate FFT from ulcerated plaque: we tested linear measurements, morphology, degree of stenosis, as well as relevant clinical factors. These parameters were measured by neuroradiologists as well as an innovative semi-automated shape analysis. Using a retrospectively established cohort, we were able to derive 3.8 mm as an optimal cranial-caudal length threshold of the filling defect that can potentially help distinguish FFT from plaque, with 88% sensitivity and 86% specificity.

We will prospectively identify consecutive patients presenting with TIA/stroke within 72 hrs of symptom onset with an ICA intraluminal filling defect on CTA. We will review the imaging data and measure the cranial-caudal length of the filling defect. Patients will receive a follow-up CTA in one week as per the current clinical standard of care, and if the defect is still unresolved, a third CTA will be repeated after a second week if unresolved, and a fourth at one month (research). We will measure cranial-caudal length of the filling defect at each time interval, blind to the previous measurements. Resolution of the filling defect at any point is diagnostic of FFT, whereas its static appearance after 1 month is diagnostic of ulcerated plaque. For this pilot study, measure rate of enrolment, adherence to study protocols, attrition rates, and proportion of patients with FFT. For the exploratory objective, we will record treatment choice, dose, and duration.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 100 participants
Allocation: N/A
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Diagnostic
Official Title: Prospective Evaluation of Intraluminal Internal Carotid Artery Free-Floating Thrombus
Actual Study Start Date : March 2015
Actual Primary Completion Date : June 2021
Actual Study Completion Date : September 2021

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Blood Clots

Arm Intervention/treatment
CT Angiogram
A research CTA scan may be required if there is no change of the imaging on the 3 CTA scans prior.
Radiation: Computed Tomographic Angiogram
1 additional non-clinical CTA per patient enrolled in the study. The estimated radiation risk from a single CTA of the neck and brain is approximately 3.6 millisieverts (mSv), an exposure similar to a single airplane flight across Canada.
Other Names:
  • CTA
  • CT Angiogram

Primary Outcome Measures :
  1. Length of intraluminal filling defect on CTA as a measure to distinguish FFT from stable ulcerated plaque [ Time Frame: 12 months ]

Secondary Outcome Measures :
  1. Prevalence of FFT among patients with ambiguous diagnosis measured by follow-up CTA scans [ Time Frame: 12 months ]
  2. Clinician treatment strategies used to manage FFT [ Time Frame: 18 months ]
  3. Future antithrombotic treatment trial measured by data collection tools and pilot data [ Time Frame: 18 months ]

Information from the National Library of Medicine

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Ages Eligible for Study:   Child, Adult, Older Adult
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • TIA/Stroke within 72 hours
  • CTA showing a symptom-relevant ICA lesion (stenosis >50%)
  • informed consent

Exclusion Criteria:

  • creatinine clearance <60 mg/ml
  • allergy to contrast media

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02405845

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Canada, Ontario
The Ottawa Hospital
Ottawa, Ontario, Canada, K1Y 4E9
Sponsors and Collaborators
Ottawa Hospital Research Institute
The Ottawa Hospital
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Principal Investigator: Carlos Torres, MD Ottawa Hospital Research Institute
Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
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Responsible Party: Ottawa Hospital Research Institute
ClinicalTrials.gov Identifier: NCT02405845    
Other Study ID Numbers: OHSN-REB 20150092-01H
First Posted: April 1, 2015    Key Record Dates
Last Update Posted: October 14, 2021
Last Verified: October 2021
Keywords provided by Ottawa Hospital Research Institute:
Internal Carotid Artery
Free-floating thrombus
Ulcerated plaque
Additional relevant MeSH terms:
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Ischemic Attack, Transient
Embolism and Thrombosis
Vascular Diseases
Cardiovascular Diseases
Brain Ischemia
Cerebrovascular Disorders
Brain Diseases
Central Nervous System Diseases
Nervous System Diseases