NCT07002450 · Ottawa Heart Institute Research Corporation
Left Atrial Imaging Prior to Cardioversion: Leveraging Computed Tomography to Rule Out Thrombus in The Emergency Department (LA CLOTTED)
(LA CLOTTED)
What this study is about
The goal of this randomly assigned clinical trial is to learn whether patients with symptomatic atrial fibrillation or atrial flutter (AF) who require heart imaging to rule out a blood clot before cardioversion would benefit from cardiac computed tomography angiography (CCT) in the emergency department (ED) compared to current the usual treatment management.
View original scientific description
The goal of this randomized clinical trial is to learn whether patients with symptomatic atrial fibrillation or atrial flutter (AF) who require heart imaging to rule out a blood clot before cardioversion would benefit from cardiac computed tomography angiography (CCT) in the emergency department (ED) compared to current standard of care management. This will be a multicenter trial evaluating whether CCT-facilitated cardioversion in the ED reduces hospital admission, reduces repeat presentations to hospital and improves patient quality of life compared to the current standard of care. Participants will undergo CCT-facilitated cardioversion or be treated according to current standard of care while in the ED and complete quality of life questionnaires in the ED and follow-up at 30 days.
Interventions
DIAGNOSTIC_TEST
Cardiac computed tomography angiography
Patients will undergo CCT according to the following protocol. A non-contrast enhanced prospective ECG-triggered image will be acquired followed by a contrast-enhanced prospective ECG-triggered image using a tri-phasic contrast protocol. Delayed CT images 60 seconds after the initial contrast-enhanced CT scan will be obtained. Cardiac CT image interpretation will be performed according to routine clinical practices in a pragmatic fashion. The LA will be assessed for filling defects and characterized based upon attenuation values. If LA 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. If the CCT shows no LA thrombus then the ED physician will be able to perform electrical and/or chemical cardioversion at their discretion.
OTHER
Standard of care management
Patients in the standard of care arm may undergo any combination of the following management strategies in the emergency department (ED) at the discretion of their treating physician: 1\. Transesophageal echocardiogram (TEE) facilitated cardioversion; 2. Rate control; 3. Consultation with inpatient cardiac specialist for assessment/management and consideration of hospital admission; 4. cardioversion after 3 weeks of anticoagulation; and/or 5. Outpatient referral to cardiac specialist or general practitioner for further management.
Primary outcome measures
Primary composite outcome
Time frame: Randomization to 30 days
Using a hierarchical win ratio: 1. All-cause death 2. Stroke, transient ischemic attack, or systemic embolism 3. Admission to hospital for a cardiac or AF related reason 4. Repeat presentation to hospital for a cardiac or AF related reason 5. Improvement in AF Effect On Quality-Of-Life Questionnaire (AFEQT) quality of life greater than or equal to 5 points
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Age ≥18 years old; and
- Primary symptomatic AF without a reversible underlying cause (e.g. sepsis, pneumonia, pulmonary embolism, hyperthyroidism)
- LA imaging required before cardioversion according to local clinical practice guidelines
Exclusion criteria
- Patients with an indication for emergency cardioversion (e.g. hemodynamic instability (systolic blood pressure\<90mmHg or signs of shock), cardiac ischemia (ongoing severe chest pain or marked ST depression on ECG \>2mm), or pulmonary edema (significant dyspnea, crackles, or hypoxia)); or
- Contraindication to CCT (renal insufficiency (eGFR\< 45ml/min/1.73m2), allergy to intravenous contrast agents, pregnancy (contraindications to radiation exposure), or inability to perform 20-second breath-hold)
Where
- Hershey, Pennsylvania
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Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jun 9, 2026 · Source of record for eligibility and locations