Left Atrial Imaging Prior to Cardioversion: Leveraging Computed Tomography to Rule Out Thrombus in The Emergency Department (LA CLOTTED)

NCT ID: NCT07002450

Last Updated: 2025-06-03

Basic Information

• Recruitment Status: NOT_YET_RECRUITING
• Clinical Phase: NA
• Total Enrollment: 190 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2025-06-15
• Study Completion Date: 2028-06-15

Brief 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 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.

Conditions

Atrial Fibrillation (AF); Atrial Flutter

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: DIAGNOSTIC
• Blinding Strategy: SINGLE

Study Groups

Standard of Care

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.

Group Type: ACTIVE_COMPARATOR

Standard of care management

Intervention Type: OTHER

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.

CCT-facilitated cardioversion arm

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.

Group Type: EXPERIMENTAL

Cardiac computed tomography angiography

Intervention Type: DIAGNOSTIC_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.

Interventions

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.

Intervention Type: DIAGNOSTIC_TEST

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.

Intervention Type: OTHER

Eligibility Criteria

Inclusion Criteria

1. Age ≥18 years old; and

2. Primary symptomatic AF without a reversible underlying cause (e.g. sepsis, pneumonia, pulmonary embolism, hyperthyroidism)

3. LA imaging required before cardioversion according to local clinical practice guidelines

Exclusion Criteria

1. 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

2. 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)

• Minimum Eligible Age: 18 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Ottawa Heart Institute Research Corporation

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Benjamin Chow, MD PhD FRCPC FACC FESC FA

Role: PRINCIPAL_INVESTIGATOR

Ottawa Heart Institute Research Corporation

Mehrdad Golian, MD MSC FRCPC

Role: PRINCIPAL_INVESTIGATOR

Ottawa Heart Institute Research Corporation

Locations

The Ottawa Hospital Civic Campus

Ottawa, Ontario, Canada

Countries

Canada

Central Contacts

Farrah Ahmed

Role: CONTACT

fahmed@ottawaheart.ca

613-696-7000 ext. 12697

Yeung Yam

Role: CONTACT

yyam@ottawaheart.ca

613-696-7000 ext. 19703

Facility Contacts

Ian Stiell, MD

Role: primary

istiell@ohri.ca

613-798-5555 ext. 18683

Other Identifiers

20240752-01T

Identifier Type: -

Identifier Source: org_study_id