Prospective Evaluation of Carotid Free-floating Thrombus

October 7, 2021 updated by: Ottawa Hospital Research Institute

Prospective Evaluation of Intraluminal Internal Carotid Artery Free-Floating Thrombus

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.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

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

Interventional

Enrollment (Actual)

100

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Canada
    • Ontario
      • Ottawa, Ontario, Canada, K1Y 4E9
        • The Ottawa Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

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

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Other: 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

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Length of intraluminal filling defect on CTA as a measure to distinguish FFT from stable ulcerated plaque
Time Frame: 12 months
12 months

Secondary Outcome Measures

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

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Ottawa Hospital Research Institute

Collaborators

The Ottawa Hospital

Investigators

  • Principal Investigator: Carlos Torres, MD, Ottawa Hospital Research Institute

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

March 1, 2015

Primary Completion (Actual)

June 1, 2021

Study Completion (Actual)

September 1, 2021

Study Registration Dates

First Submitted

March 11, 2015

First Submitted That Met QC Criteria

March 27, 2015

First Posted (Estimate)

April 1, 2015

Study Record Updates

Last Update Posted (Actual)

October 14, 2021

Last Update Submitted That Met QC Criteria

October 7, 2021

Last Verified

October 1, 2021

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • OHSN-REB 20150092-01H

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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