Atrial Fibrillation (AF)LA CLOTTEDNCT07002450
Left Atrial Imaging Prior to Cardioversion: Leveraging Computed Tomography to Rule Out Thrombus in The Emergency Department (LA CLOTTED)
A study testing Cardiac computed tomography angiography in people with Atrial Fibrillation (AF) and Atrial Flutter, run by Ottawa Heart Institute Research Corporation at 3 sites in 2 countries.
Trial summary
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… Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Atrial Fibrillation (AF), Atrial Flutter
- What is being tested?
- Cardiac computed tomography angiography
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 190 participants
- Where
- 3 sitesin 2 countries
- Study dates
- 15 Jun 2025to 15 Jun 2028
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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
Who cannot join
- 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)
Trial locations and contacts
3 sites in 2 countries. Contact the study team or a site near you to ask about taking part.
3 sites in 2 countries
Canada2 sites, 2 recruiting
- Recruiting
The Ottawa Hospital Civic Campus
Ottawa, Ontario, K1Y 1J8
Ian Stiell, MD, 613-798-5555 ext. 18683, istiell@ohri.ca
Ian Stiell, MD
- Recruiting
Sunnybrook Health Sciences Centre
Toronto, Ontario, M4N 3M5
Idan Roifman, MD, 416-480-6100 ext. Ext. 6771, Idan.Roifman@sunnybrook.ca
Idan Roifman, MD
United States1 site, 1 recruiting
- Recruiting
Penn State Health Milton S. Hershey Medical Center
Hershey, Pennsylvania, 17033
Murtaza Akhter, MD, 603-418-2868, makhter@pennstatehealth.psu.edu
About this study
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.
Read the detailed description
Atrial fibrillation and atrial flutter (AF) are the most common cardiac arrhythmias worldwide resulting in frequent visits to the emergency department (ED). Some patients can undergo chemical or electrical cardioversion to restore their heart back to a sinus rhythm. However, if a patient is not on blood thinners and the duration of AF is prolonged then blood clots may form in the heart increasing the risk of stroke after cardioversion. Therefore, some patients must undergo heart imaging to rule out any blood clots before cardioversion is considered safe. Transesophageal echocardiography (TEE) is commonly used to rule out blood clots, but it is not readily available in all EDs often resulting in hospital admission to facilitate this test or deferring cardioversion until 3 weeks of blood thinners have been completed.
Cardiac computed tomography angiography (CCT) is a more readily available alternative to TEE that can be done rapidly in the ED. CCT has excellent sensitivity and specificity compared to TEE for identifying cardiac thrombus. If there is no thrombus detected on the CCT then patients could be immediately cardioverted to sinus rhythm thus avoiding an unnecessary hospital admission and reducing the symptom burden associated with remaining in AF.
This study is a multicenter randomized trial that will evaluate the effectiveness of using CCT facilitated cardioversion in the ED compared to current standard of care management.
- Conditions
- Atrial Fibrillation (AF), Atrial Flutter
- Being tested
- Cardiac computed tomography angiography, Standard of care management
- Keywords
- Cardiac computed tomography angiography, Cardioversion, Atrial flutter, Atrial fibrillation
- Medical subject headings
- Atrial Fibrillation, Atrial Flutter
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Cardiac computed tomography angiographyDiagnostic test
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.
Standard of care managementOther
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:
- 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.
| Study group | Role | What they receive |
|---|---|---|
| Standard of Care | Active comparator | Patients in the control arm will be treated according to current standard of care as determined by the primary treating emergency department physician and may vary by institution and physician. Treatment in the standard of care group may include a rate control strategy with or without a planned cardioversion after 3 weeks of anticoagulation, deferring management for outpatient evaluation, request for TEE-facilitated cardioversion in the ED, or specialist consultation for further management or admission to hospital. Receives: Other: Standard of care management |
| CCT-facilitated cardioversion arm | Experimental | Patients in this arm will undergo cardiac computed tomography angiography (CCT) to evaluate for a left atrial/left atrial appendage (LA) thrombus. If the CCT shows no LA thrombus then the emergency department physician will be able to perform electrical and/or chemical cardioversion at their discretion. If the CCT shows a LA thrombus then cardioversion will be contraindicated and further management will be at the discretion of the treating physician. Receives: Diagnostic Test: Cardiac computed tomography angiography |
What is being measured
The primary outcome is the main question the study is designed to answer.
Primary composite outcome
Using a hierarchical win ratio:
- All-cause death
- Stroke, transient ischemic attack, or systemic embolism
- Admission to hospital for a cardiac or AF related reason
- Repeat presentation to hospital for a cardiac or AF related reason
- Improvement in AF Effect On Quality-Of-Life Questionnaire (AFEQT) quality of life greater than or equal to 5 points
Measured: Randomization to 30 days
Secondary outcomes (12)
Composite objective outcomes
Using a hierarchical win ratio:
- All-cause death
- Stroke, transient ischemic attack, or systemic embolism
- Admission to hospital for a cardiac or AF releated reason
- Repeat presentation to hospital for a cardiac or AF related reason
Measured: Randomization to 30 days
All-cause death
Death from any cause
Measured: Randomization to 30 days
Cardiovascular death
Death due to a cardiovascular cause
Measured: Randomization to 30 days
Stroke, transient ischemic attack, or systemic embolism
Stroke is defined as a central nervous system infarction of the brain, spinal cord, or retina in a vascular distribution based on pathologic, imaging, or clinical evidence with symptoms persisting for ≥24 hours or until death.
Transient ischemic attack is defined as a transient episode of neurologic dysfunction due to focal brain, spinal cord, or retinal ischemia without acute infarction or tissue injury.
Systemic embolism is defined as an abrupt vascular insufficiency associated with clinical or radiologic evidence of arterial occlusion in the absence of other likely mechanisms.
Measured: Randomization to 30 days
Hospital admission for a cardiac or AF related reason
To count as a hospital admission for a cardiac or AF related reason it should meet the following criteria:
- Duration of admission should exceed 24 hours; AND
- Admission is due to the following reasons:
- Admission at index hospital presentation:
- Heart rate>100bpm at rest or >110bpm with ambulation despite a trial of rate control; or
- Complication related to the treatment of AF (including significant incidental findings on CCT leading to admission)
- Admission at subsequent hospital presentation:
- Hospitalization due to a cardiac reason such as heart failure, syncope, palpitations/arrhythmia, angina or acute coronary syndrome
Measured: Randomization to 30 days
Repeat presentation to the emergency department
Repeat presentation to the emergency department due to a cardiac reason such as heart failure, syncope, palpitations/arrhythmia, angina or acute coronary syndrome
Measured: Randomization to 30 days
AFEQT quality of life
Change in AF Effect On Quality-Of-Life Questionnaire (AFEQT) quality of life The AFEQT is a 20-item, self-administered instrument that quantifies symptoms, daily activities, treatment concern, and treatment satisfaction. Scores are transformed to a range from 0-100, in which higher scores reflect better health status.
Measured: Randomization to 30 days
SF-36 quality of life
Change in 36-Item Short Form Health Survey (SF-36) quality of life. The SF-36 questionnaire consists of eight scales yielding two summary measures: physical and mental health. The mental health measure is composed of vitality (4 items), social functioning (2 items), role-emotional (3 items), and mental health (5 items). Scores are transformed to a range of 0-100, in which higher scores reflect better health status.
Measured: Randomization to 30 days
Bleeding
Bleeding events as defined by the Bleeding Academic Research Consortium
Measured: Randomization to 30 days
Admission to hospital for acute kidney injury
Definition of acute kidney injury according to the Kidney Disease Improving Global Outcomes:
- Increase in SCr by ≥ 0.3 mg/dl (≥ 26.5 µmol/l) within 48 hours; or
- Increase in SCr to ≥ 1.5 times baseline, which is known or presumed to have occurred within the prior 7 days; or
- Urine volume <0.5 ml/kg/h for 6 hours
Measured: Randomization to 30 days
Length of stay in the emergency department
Length of stay in emergency department in minutes, from time of arrival to time of discharge or admission
Measured: From time of arrival until time of discharge or admission (approximately 3 hours)
Normal sinus rhythm
Being in normal sinus rhythm at the 30 day follow up. Heart rhythm will be determined by electrocardiography.
Measured: Randomization to 30 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Jun 2025
- Study start15 Jun 2025
- Primary completion15 Jun 2028 (estimated)
- Study completion15 Jun 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Atrial Fibrillation (AF)Studies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Diagnosis
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Investigator
- Enrolment
- 190 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Ottawa Heart Institute Research Corporation
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Benjamin Chow, MD PhD FRCPC FACC FESC FA, Principal investigator, Ottawa Heart Institute Research CorporationMehrdad Golian, MD MSC FRCPC, Principal investigator, Ottawa Heart Institute Research Corporation
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07002450
- Sponsor's protocol ID
- 20240752-01T
- Acronym
- LA CLOTTED
- Status last verified
- Jun 2026
- First submitted
- 8 May 2025
- Last updated
- 9 Jun 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: The study data, protocol, SAP, ICF, and CSR will be made available at study completion/publication.
Study at a glance
From the registry record, last updated by the sponsor on 9 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Left Atrial Imaging Prior to Cardioversion: Leveraging Computed Tomography to Rule Out Thrombus in The Emergency Department (LA CLOTTED)
- ClinicalTrials.gov ID
- NCT07002450
- Acronym / sponsor ID
- LA CLOTTED / 20240752-01T
- Conditions
- Atrial Fibrillation (AF), Atrial Flutter
- Keywords
- Cardiac computed tomography angiography, Cardioversion, Atrial flutter, Atrial fibrillation
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 190 participants (estimated)
- Lead sponsor
- Ottawa Heart Institute Research CorporationUniversity, hospital or other
- Study start
- 15 Jun 2025 (actual)
- Primary completion
- 15 Jun 2028 (estimated)
- Study completion
- 15 Jun 2028 (estimated)
- First posted
- 3 Jun 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
Atrial fibrillation and atrial flutter (AF) are the most common cardiac arrhythmias worldwide resulting in frequent visits to the emergency department (ED). Some patients can undergo chemical or electrical cardioversion to restore their heart back to a sinus rhythm. However, if a patient is not on blood thinners and the duration of AF is prolonged then blood clots may form in the heart increasing the risk of stroke after cardioversion. Therefore, some patients must undergo heart imaging to rule out any blood clots before cardioversion is considered safe. Transesophageal echocardiography (TEE) is commonly used to rule out blood clots, but it is not readily available in all EDs often resulting in hospital admission to facilitate this test or deferring cardioversion until 3 weeks of blood thinners have been completed.
Cardiac computed tomography angiography (CCT) is a more readily available alternative to TEE that can be done rapidly in the ED. CCT has excellent sensitivity and specificity compared to TEE for identifying cardiac thrombus. If there is no thrombus detected on the CCT then patients could be immediately cardioverted to sinus rhythm thus avoiding an unnecessary hospital admission and reducing the symptom burden associated with remaining in AF.
This study is a multicenter randomized trial that will evaluate the effectiveness of using CCT facilitated cardioversion in the ED compared to current standard of care management.
Study design
- Primary purpose
- Diagnosis
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (investigator)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Standard of Care | Active comparator | Other: Standard of care managementPatients in the control arm will be treated according to current standard of care as determined by the primary treating emergency department physician and may vary by institution and physician. Treatment in the standard of care group may include a rate control strategy with or without a planned cardioversion after 3 weeks of anticoagulation, deferring management for outpatient evaluation, request for TEE-facilitated cardioversion in the ED, or specialist consultation for further management or admission to hospital. |
| CCT-facilitated cardioversion arm | Experimental | Diagnostic Test: Cardiac computed tomography angiographyPatients in this arm will undergo cardiac computed tomography angiography (CCT) to evaluate for a left atrial/left atrial appendage (LA) thrombus. If the CCT shows no LA thrombus then the emergency department physician will be able to perform electrical and/or chemical cardioversion at their discretion. If the CCT shows a LA thrombus then cardioversion will be contraindicated and further management will be at the discretion of the treating physician. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- 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
Key exclusion criteria (2 listed)
- 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)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Cardiac computed tomography angiographyPatients 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. | Diagnostic test | CCT-facilitated cardioversion arm |
| Standard of care managementPatients 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. | Other | Standard of Care |
Primary outcome
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
12 secondary outcomes
Composite objective outcomes
Time frame: Randomization to 30 days
All-cause death
Time frame: Randomization to 30 days
Cardiovascular death
Time frame: Randomization to 30 days
Stroke, transient ischemic attack, or systemic embolism
Time frame: Randomization to 30 days
Hospital admission for a cardiac or AF related reason
Time frame: Randomization to 30 days
Repeat presentation to the emergency department
Time frame: Randomization to 30 days
AFEQT quality of life
Time frame: Randomization to 30 days
SF-36 quality of life
Time frame: Randomization to 30 days
Bleeding
Time frame: Randomization to 30 days
Admission to hospital for acute kidney injury
Time frame: Randomization to 30 days
Length of stay in the emergency department
Time frame: From time of arrival until time of discharge or admission (approximately 3 hours)
Normal sinus rhythm
Time frame: Randomization to 30 days
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 9 Jun 2026.
- Individual participant dataSharing planned: Yes. The study data, protocol, SAP, ICF, and CSR will be made available at study completion/publication.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Benjamin Chow, MD PhD FRCPC FACC FESC FA principal investigator
Ottawa Heart Institute Research Corporation
Mehrdad Golian, MD MSC FRCPC principal investigator
Ottawa Heart Institute Research Corporation
3 sites in 2 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Cardiac computed tomography angiography in people with Atrial Fibrillation (AF) and Atrial Flutter, run by Ottawa Heart Institute Research Corporation at 3 sites in 2 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 9 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 3 sites in Canada, United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Farrah Ahmed (613-696-7000 ext. 12697, fahmed@ottawaheart.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Primary composite outcome (time frame: Randomization to 30 days). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 9 Jun 2026.