An observational study in Atrial Fibrillation, Stroke Prevention in Patients With Atrial Fibrillation and Left Atrial Appendage Closure, sponsored by National Medical Research Center for Therapy and Preventive Medicine. Recruiting at 1 site in Russia. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-05-08.
Sponsored by National Medical Research Center for Therapy and Preventive Medicine · Observational
This is a prospective, non-randomized, observational cohort study conducted at the FSBI "NMRC TPM" of the Ministry of Healthcare of the Russian Federation. Left atrial appendage closure (LAAC) has been shown to be non-inferior to oral anticoagulation for preventing cardioembolic events in patients with atrial fibrillation. However, the optimal post-procedural antithrombotic regimen following LAAC remains unclear, with no consensus on evidence-based therapy. Given current trends in cardiology favoring reduced-intensity antithrombotic strategies, this study aims to contribute to the evidence base by evaluating whether LAAC followed by reduced-dose apixaban (2.5 mg BID) for 3 months with subsequent complete withdrawal of antithrombotic therapy is superior to long-term standard-dose DOAC therapy in patients with non-valvular atrial fibrillation.
This is a prospective, non-randomized, observational cohort study enrolling patients with non-valvular atrial fibrillation (NVAF).
Participants will be assigned to one of two groups based on clinical indication. LAAC group: Patients with NVAF undergoing left atrial appendage closure (LAAC) who will receive reduced-dose apixaban (2.5 mg BID) for 3 months, followed by complete withdrawal of antithrombotic therapy. The criterion for anticoagulation discontinuation will be a satisfactory result on transesophageal echocardiography (TEE) or cardiac computed tomography (CT) at 3 months post-implantation, confirming adequate device sealing without significant peri-device leak or device-related thrombosis. Participants will undergo additional TEE or cardiac CT at 6 and 12 months after the procedure and will be followed up by telephone at 18, 24, 30, and 36 months after enrollment.
Control group: Patients with NVAF indicated for long-term oral anticoagulation will receive standard full-dose direct oral anticoagulant (DOAC) therapy. Participants in the control group will be followed up by telephone at 3, 6, 12, 18, 24, 30, and 36 months after enrollment.
Observation period: 36 months. Devices used for LAAC will include the Watchman FLX (Boston Scientific, St. Paul, Minnesota, USA) and the Amplatzer Amulet (Abbott, St. Paul, Minnesota, USA).
Primary endpoint: A composite of major bleeding (BARC type ≥3), all-cause mortality, ischemic stroke, systemic embolism, device-related thrombosis (DRT), and significant peri-device leak over 36 months of follow-up.
Secondary endpoints: Individual components of the primary composite endpoint over 36 months of follow-up.
Propensity score matching will be used to create balanced comparison groups for statistical analysis, adjusting for baseline differences between cohorts.
4,009 studies on the registry are indexed under Atrial Fibrillation; 961 are open to participants now.
This study's planned enrollment of 464 is above the median of 300 across 1,400 observational studies indexed under Atrial Fibrillation.
Browse Atrial Fibrillation studies →National Medical Research Center for Therapy and Preventive Medicine is the lead sponsor of 29 studies on the registry; 11 are open to participants now.
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The study population comprises adults with documented non-valvular atrial fibrillation who require stroke prevention therapy. Two distinct cohorts will be enrolled:
Cohort 1 (LAAC group): Patients with non-valvular atrial fibrillation and elevated thromboembolic risk who have relative or absolute contraindications to long-term oral anticoagulation, history of bleeding complications on anticoagulation, or patient preference for a non-pharmacological stroke prevention strategy. These patients will undergo percutaneous left atrial appendage closure.
Cohort 2 (Control group): Patients with non-valvular atrial fibrillation and elevated thromboembolic risk who are appropriate candidates for and willing to continue long-term standard-dose direct oral anticoagulant therapy.
Both cohorts will be recruited from the same institution during the same time period to minimize selection bias related to temporal trends in clinical practice.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
LVEF (left ventricular ejection fraction)
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Child-Pugh class
A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
NYHA class (heart failure)
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Patients undergoing left atrial appendage closure (LAAC) with Watchman FLX or Amplatzer Amulet devices, followed by reduced-dose apixaban (2.5 mg BID) for 3 months with subsequent complete withdrawal of antithrombotic therapy
Device: Left Atrial Appendage Closure · Drug: Apixaban 2.5 mg BID
Patients receiving long-term standard-dose direct oral anticoagulant (DOAC) therapy per current guidelines
Drug: Standard-dose DOAC
Percutaneous left atrial appendage closure using Watchman FLX (Boston Scientific) or Amplatzer Amulet (Abbott) devices
Also known as: LAAC
Reduced-dose apixaban 2.5 mg BID for 3 months post-LAAC, followed by complete withdrawal of antithrombotic therapy
Standard-dose DOAC therapy (e.g., apixaban 5 mg BID, rivaroxaban 20 mg daily, or other DOAC per physician discretion) continued for the duration of follow-up
Composite of major adverse events
Composite endpoint including: bleeding events (BARC type ≥3), all-cause death, ischemic stroke, systemic embolism, device-related thrombosis (DRT), and peri-device leak (\>3 mm)
Time frame: 36 months from enrollment
Major bleeding events
Incidence of bleeding events classified as BARC type 3 or higher
Time frame: 36 months from enrollment
All-cause mortality
Incidence of death from any cause
Time frame: 36 months from enrollment
Ischemic stroke
Incidence of ischemic cerebrovascular events confirmed by imaging
Time frame: 36 months from enrollment
Systemic embolism
Incidence of systemic embolic events excluding stroke
Time frame: 36 months from enrollment
Device-related thrombosis
Incidence of thrombus formation on the LAAC device detected by imaging (LAAC group only)
Time frame: 36 months from enrollment
Peri-device leak
Incidence of peri-device leak \>3 mm detected by transesophageal echocardiography or cardiac CT (LAAC group only)
Time frame: 36 months from enrollment
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National Medical Research Center for Therapy and Preventive Medicine