Left Atrial Imaging Prior to Cardioversion: Leveraging Computed Tomography to Rule Out Thrombus (LACLOT)

Evaluating contrast enhanced ECG-gated cardiac CT (CCT) as an alternative to transesophageal echocardiography (TEE) to expedite cardioversion of atrial fibrillation (AF), improve patient care and reduce hospital admissions for AF and atrial flutter.

Study Overview

• Status: Completed
• Conditions: Atrial Fibrillation
• Intervention / Treatment: Diagnostic test: Transesophageal Echocardiography (TEE); Diagnostic test: Contrast enhanced ECG-gated cardiac CT (CCT)

• Study Type: Interventional
• Enrollment (Actual): 102
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Canada
  • Ontario
    • Ottawa, Ontario, Canada, K1Y 4W7
      • University of Ottawa Heart Institute

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Admitted patients who require LA imaging prior to cardioversion
2. Age ≥18 years old
3. Able and willing to comply with the study procedures

Exclusion Criteria:

1. Indication for acute cardioversion (e.g. hemodynamic instability, acute coronary syndrome (ACS), or pulmonary edema)
2. Unwillingness or inability to provide informed consent

3. Contraindication to Cardiac CT

   • Severe renal insufficiency(GFR< 45ml/min)
   • Allergy to intravenous contrast agents
   • Contraindications to radiation exposure (for example, pregnancy)
   • Inability to perform 20-second breath-hold

4. Contraindication to TEE

   • Unrepaired tracheoesophageal fistula
   • Esophageal obstruction or stricture
   • Perforated hollow viscus
   • Poor airway control
   • Severe respiratory depression
   • Uncooperative, unsedated patient

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: TEE arm; TEE will be performed as per clinical routine using multiple standard tomographic planes to rule-out LA/LAA thrombus. Echocardiographic analysis will include: LAA-emptying velocity, and grading the severity of LAA spontaneous ECHO. The severity of the SEC will be graded on a 4 point scale with 1 = minor homogeneous contrast enhancement, 2 = significant homogeneous contrast enhancement, 3 = significant, dense, and inhomogeneous, slow-moving contrast, and 4 = dense slow-moving contrast.	Diagnostic test: Transesophageal Echocardiography (TEE); TEE is considered the reference standard to rule-out left atrial (LA) and left atrial appendage (LAA) thrombus prior to cardioversion. Several studies have examined the accuracy of TEE for detecting LAA thrombus. Compared to autopsy and intraoperative findings, TEE has a mean sensitivity of 100% and mean specificity of 99%. Although the gold standard, a TEE-guided therapy is still associated with an embolic rate of 0.8%.
Experimental: CCT arm; As per local protocol, a non-contrast enhanced prospective ECG-triggered image acquisition will be acquired. This will be followed by a contrast-enhanced prospective ECG-triggered will be acquired using a tri-phasic contrast protocols. Delayed CT images will be acquired 60 seconds after the initial contrast-enhanced CT scan.Cardiac CT image interpretation will be performed as per clinical routine. The LA and LAA will be assess for filling defects and characterized based upon attenuation values. If LA/LAA thrombus cannot be excluded, filling defects will be assessed on the delay images. Increases in attenuation would be consistent with pseudo-thrombus from 'slow flow' and 'incomplete opacification'. Areas where attenuation does not change significantly (persistent filling defect) will be diagnosed as thrombus. It will be recommended that patients with thrombus will undergo TEE.	Diagnostic test: Transesophageal Echocardiography (TEE); TEE is considered the reference standard to rule-out left atrial (LA) and left atrial appendage (LAA) thrombus prior to cardioversion. Several studies have examined the accuracy of TEE for detecting LAA thrombus. Compared to autopsy and intraoperative findings, TEE has a mean sensitivity of 100% and mean specificity of 99%. Although the gold standard, a TEE-guided therapy is still associated with an embolic rate of 0.8%.; Diagnostic test: Contrast enhanced ECG-gated cardiac CT (CCT); Contrast enhanced ECG-gated cardiac CT (CCT) is a sensitive, noninvasive alternative method used to exclude of left atrial and LAA thrombus. CCT provides high spatial and good temporal resolution and its ability to detect thrombus has been evaluated. CCT, compared to TEE, for the exclusion of thrombus in the LAA had a sensitivity and specificity of 100% and 99.3%, respectively. A high sensitivity is needed to minimize risk of embolus, and if a thrombus is detected on CT, a confirmatory TEE may be performed or patients may receive anticoagulation. Some argue that the potential benefits of CT and its lower associated procedural risk, the risk:benefit ratio would still favour CT.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to Imaging	This outcome was measured by calculating the time between admission and imaging.	From admission to imaging/spontaneous cardioversion, up to approximately 30 days.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to Cardioversion	This outcome was measured by calculating the time between admission and cardioversion.	From admission to cardioversion, up to approximately 30 days

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to Hospital Discharge	This outcome was measured by calculating the time between admission and hospital discharge.	From admission to hospital discharge, up to approximately 90 days.
QoL	This outcome was calculated from the following QoLs: European Quality of Life 5 Dimensions 5 Level Version (EQ-5D-5L) and Atrial Fibrillation Impact (AFImpact). EQ-5D-5L health score is a continuous scale from 0 to 100 with 100 being the best outcome. AFImpact scores were calculated using a seven-point Likert Scale (1=none of the time, 7=all of the time). AFImpact-Vitality, Emotional Distress, Sleep score (AFImpact-VEDS) was calculated using all questions in the questionnaire. The difference between AFImpact-VEDS scores at hospital admission and discharge was calculated where minimum change in score is 0 and maximum change in score is 108. AFImpact-emotional distress subscale score was calculated using 8 questions about emotional distress. The difference between AFImpact emotional distress scores at hospital admission and discharge was calculated where minimum change in score is 0 and maximum change in score is 48. The higher change in AFImpact scores represented a better outcome.	At hospital discharge

Collaborators and Investigators

• Sponsor: Ottawa Heart Institute Research Corporation
• Investigators: Principal Investigator: Benjamin Chow, MD, UOHI

Study record dates

Study Major Dates

• Study Start (Actual): June 26, 2020
• Primary Completion (Actual): November 21, 2023
• Study Completion (Actual): January 12, 2024

Study Registration Dates

• First Submitted: January 6, 2020
• First Submitted That Met QC Criteria: January 8, 2020
• First Posted (Actual): January 10, 2020

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: February 20, 2025
• Last Verified: September 1, 2024

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Cardiovascular Diseases; Pathologic Processes; Heart Diseases; Arrhythmias, Cardiac; Atrial Fibrillation
• Other Study ID Numbers: 201900117-01H

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No