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Prospective Evaluation of Carotid Free-floating Thrombus

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. 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

Tracking Information
First Submitted Date  ICMJE March 11, 2015
First Posted Date  ICMJE April 1, 2015
Last Update Posted Date October 14, 2021
Actual Study Start Date  ICMJE March 2015
Actual Primary Completion Date June 2021   (Final data collection date for primary outcome measure)
Current Primary Outcome Measures  ICMJE
 (submitted: March 27, 2015)
Length of intraluminal filling defect on CTA as a measure to distinguish FFT from stable ulcerated plaque [ Time Frame: 12 months ]
Original Primary Outcome Measures  ICMJE Same as current
Change History
Current Secondary Outcome Measures  ICMJE
 (submitted: March 27, 2015)
  • Prevalence of FFT among patients with ambiguous diagnosis measured by follow-up CTA scans [ Time Frame: 12 months ]
  • Clinician treatment strategies used to manage FFT [ Time Frame: 18 months ]
  • Future antithrombotic treatment trial measured by data collection tools and pilot data [ Time Frame: 18 months ]
Original Secondary Outcome Measures  ICMJE Same as current
Current Other Pre-specified Outcome Measures Not Provided
Original Other Pre-specified Outcome Measures Not Provided
Descriptive Information
Brief Title  ICMJE Prospective Evaluation of Carotid Free-floating Thrombus
Official Title  ICMJE Prospective Evaluation of Intraluminal Internal Carotid Artery Free-Floating Thrombus
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.

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.

Study Type  ICMJE Interventional
Study Phase  ICMJE Not Applicable
Study Design  ICMJE Allocation: N/A
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Diagnostic
Condition  ICMJE
  • Stroke
  • Transient Ischemic Attack
Intervention  ICMJE 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
Study Arms  ICMJE CT Angiogram
A research CTA scan may be required if there is no change of the imaging on the 3 CTA scans prior.
Intervention: Radiation: Computed Tomographic Angiogram
Publications * Torres C, Lum C, Puac-Polanco P, Stotts G, Shamy MCF, Blacquiere D, Lun R, Dave P, Bharatha A, Menon BK, Thornhill R, Momoli F, Dowlatshahi D. Differentiating Carotid Free-Floating Thrombus From Atheromatous Plaque Using Intraluminal Filling Defect Length on CTA: A Validation Study. Neurology. 2021 Aug 24;97(8):e785-e793. doi: 10.1212/WNL.0000000000012368. Epub 2021 Jun 14.

*   Includes publications given by the data provider as well as publications identified by Identifier (NCT Number) in Medline.
Recruitment Information
Recruitment Status  ICMJE Completed
Actual Enrollment  ICMJE
 (submitted: October 7, 2021)
Original Estimated Enrollment  ICMJE
 (submitted: March 27, 2015)
Actual Study Completion Date  ICMJE September 2021
Actual Primary Completion Date June 2021   (Final data collection date for primary outcome measure)
Eligibility Criteria  ICMJE

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
Sex/Gender  ICMJE
Sexes Eligible for Study: All
Ages  ICMJE Child, Adult, Older Adult
Accepts Healthy Volunteers  ICMJE No
Contacts  ICMJE Contact information is only displayed when the study is recruiting subjects
Listed Location Countries  ICMJE Canada
Removed Location Countries  
Administrative Information
NCT Number  ICMJE NCT02405845
Other Study ID Numbers  ICMJE OHSN-REB 20150092-01H
Has Data Monitoring Committee No
U.S. FDA-regulated Product Not Provided
IPD Sharing Statement  ICMJE Not Provided
Responsible Party Ottawa Hospital Research Institute
Study Sponsor  ICMJE Ottawa Hospital Research Institute
Collaborators  ICMJE The Ottawa Hospital
Investigators  ICMJE
Principal Investigator: Carlos Torres, MD Ottawa Hospital Research Institute
PRS Account Ottawa Hospital Research Institute
Verification Date October 2021

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP