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

Study Overview
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Brief Summary
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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.

Official Title
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Left Atrial Imaging Prior to Cardioversion: Leveraging Computed Tomography to Rule Out Thrombus

Conditions
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Atrial Fibrillation

Intervention / Treatment
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* Diagnostic Test: Contrast enhanced ECG-gated cardiac CT (CCT)
* Diagnostic Test: Transesophageal Echocardiography (TEE)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Admitted patients who require LA imaging prior to cardioversion Age ≥18 years old Able and willing to comply with the study procedures Exclusion Criteria: Indication for acute cardioversion (e.g. hemodynamic instability, acute coronary syndrome (ACS), or pulmonary edema) Unwillingness or inability to provide informed consent 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 Contraindication to TEE Unrepaired tracheoesophageal fistula Esophageal obstruction or stricture Perforated hollow viscus Poor airway control Severe respiratory depression Uncooperative, unsedated patient

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

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


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: TEE arm<br>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)<br>* 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%.<br>|
| Experimental: CCT arm<br>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: Contrast enhanced ECG-gated cardiac CT (CCT)<br>* 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.<br>Diagnostic Test: Transesophageal Echocardiography (TEE)<br>* 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%.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time to cardioversion |  | Up to 30 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Hospital admission rate |  | Up to 30 days |