Efficacy of Early Rhythm Control Therapy in Patients With Subclinical Atrial Fibrillation (SubclincalAF)

February 27, 2026 updated by: Ju Youn Kim, Samsung Medical Center

The goal of this study to find out the efficacy of early rhythm therapy in patients with subclinical atrial fibrillation detected by Cardiac Electronic Implantable Devices.

Early rhythm therapy includes antiarrhythmic drug, cardioversion, and catheter ablation. The general control group receives general management without the above atrial fibrillation rhythm control treatment.

Researchers will compare early rhythm control groups to general control groups to see if early rhythm therapy works to reduce the atrial fibrillation burden by 50% or more, or decrease the incidence of clinical AF documentation.

Participants will:

  • Randomly allocated to two groups at a 1:1 ratio.
  • Receive the treatment according to their assigned group.
  • Visit the clinic once every three months for checkups and tests.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

There have been reports that early rhythm control therapy reduces various heart events in patients with atrial fibrillation. The definition of "early" atrial fibrillation defined in this study was defined as a patient within one year of diagnosis. This means clinical atrial fibrillation diagnosed by 12-lead electrocardiogram.

Atrial high rate episode (AHRE) may be found through various Cardiac Electronic Implantable Devices (CIED), which is defined as subclinical atrial fibrillation. There have been many studies on the risk of such subclinical atrial fibrillation causing cerebral infarction, and meta-analysis results show that there is a high risk of thromboembolism if there is an episode of 30 seconds or the sum of duration is more than 24 hours. However, there is no research on the rhythm control therapy for patients with subclinical atrial fibrillation, and this study might be considered as an important factor in determining the truly early atrial fibrillation treatment guideline. Therefore, this study aims to find out the efficacy of early rhythm therapy in patients with subclinical atrial fibrillation detected by Cardiac Electronic Implantable Devices.

This study is a randomized, multicenter, prospective, interventional study to observe the efficacy of early rhythm control treatment compared to general control treatment in patients with subclinical atrial fibrillation. According to the electronic random assignment program, it is divided into two groups (early rhythm control group, general control group) and allocated at a 1:1 ratio. This study is open-label study. Early rhythm control groups get rhythm control treatment for atrial fibrillation based on guidelines. This includes antiarrhythmic drug, cardioversion, and catheter ablation. The general control group receives general management (observation, heart rate control treatment if necessary) without the above atrial fibrillation rhythm control treatment. In both groups, appropriate anticoagulant treatment is given if there is an indication of cerebral infarction prevention associated with atrial fibrillation.

Study Type

Interventional

Enrollment (Estimated)

520

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

  • Name: Ju Youn Kim, Clinical assistant professor, MD, Ph.D
  • Phone Number: 82-2-3410-3419
  • Email: kzzoo921@gmail.com

Study Locations

  • South Korea
    • Seoul
      • Seoul, Seoul, South Korea, 06351
        • Recruiting
        • Samsung Medical Center
        • Contact:
          • Kim Ju Youn, Clinical assistant professor, Ph.D
          • Phone Number: 82+ 2-3410-3419
          • Email: kzzoo921@gmail.com

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Among patients with Cardiac implantable electronic device (CIED), subjects with atrial high rate episodes found Cardiac implantable electronic devices: implantable loop recorder, pacemaker, implantable cardioverter defibrillator(ICD), cardiac resynchronized therapy(CRT)
  • Patients aged 19 or older who have agreed to the study (if voluntary consent is deemed difficult, consent from legal representatives is obtained together)
  • If the accumulated period of the atrial high rate episode during the three-month observation period is more than 21 hours
  • Patients whose atrial fibrillation has not been confirmed by electrocardiogram or holter monitoring within the past year from the time atrial high rate episode was detected

However, enrollment is possible even if it includes one of the following two cases ⓐ Patients diagnosed and recorded as atrial fibrillation on medical records but not confirmed by electrocardiogram or holter monitoring

ⓑ If there is a record of atrial fibrillation, but Paroxysmal AF less than 30 seconds

Exclusion Criteria:

  • Patients deemed inappropriate to participate in the study by the investigator
  • Patients diagnosed with atrial fibrillation with 12-lead electrocardiogram or holter within the past year prior to participation in the study
  • Patients taking Class Ic, III of antiarrhythmic drugs prior to study participation
  • Patients who have had rhythm control treatments such as Radiofequency catheter ablation (RFCA), Total thoracoscopic ablation (TTA), Maze procedure (MAZEop), and antiarrhythmic treatment due to atrial fibrillation (except for CTI ablation with AFL)
  • Patients whose life expectancy is less than one year (e.g., patients who can't even have a heart transplant, patients who receive DNR, Patients in hospice wards who refuse life-sustaining treatment, terminal cancer patients who cannot receive radiation or chemotherapy, etc.)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: early rhythm control group

Early rhythm control group receives atrial fibrillation rhythm control treatment based on guidelines. This includes antiarrhythmic treatment, cardioversion, and catheter ablation.

Antiarrhythmic drugs include flecainide, propafenone, pilsicainide, sotalol, amiodarone, dronedarone and so on, and the doctor chooses the drug in consideration of structural heart disease, coronary artery disease, abnormal left ventricular hypertrophy, and heart failure.(Refer to the Korean Heart rhythm Society atrial Fibrillation Treatment Guidelines) Catheter ablation is a procedure that uses high-frequency energy to block the site of tachycardia in the heart. Cardioversion is a procedure that converts the electrical activity of the heart to sinus rhythm by directly giving electric shock on the surface of the heart. Catheter ablation or cardioversion is a treatment method performed only when clinical atrial fibrillation is confirmed.
Drug: early rhythm control group
flecainide, propafenone, pilsicainide, sotalol, amiodarone, dronedarone and so on
Procedure: cardioversion, catheter ablation
only when clinical atrial fibrillation (if atrial fibrillation continued for more than 30 seconds on a 12-lead electrocardiogram or holter monitoring) is confirmed
Active Comparator: general control group
The general control group receives general management without the above atrial fibrillation rhythm control treatment.(Observation without additional medication, or heart rate control treatment if necessary) Heart rate control drugs such as beta-blockers, calcium channel blockers (Non-dihydropyridine CCB), and digoxin are used for heart rate control according to the doctor's prescription.
Other: general control
General management without atrial fibrillation rhythm control treatment.(Observation without additional medication, or heart rate control treatment if necessary) Heart rate control drugs such as beta-blockers, calcium channel blockers (Non-dihydropyridine CCB), and digoxin are used for heart rate control according to the doctor's prescription.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Less than 50% reduction in atrial fibrillation(AF) burden or clinical AF documentation Incidence Rate (AF recurrence rate)
Time Frame: From enrollment to 1 year

Recurrence is defined as

  • either a less than 50% reduction in AF burden or the detection/occurrence of clinical AF AF control (efficacy) is defined as

  • reduction in AF burden of 50% or more

    10% difference in the recurrence rate between the two groups using a comparison of proportions.

Kaplan-Meier survival analysis will be performed, and the Log-rank test will be used to compare the groups.

A Cox proportional-hazards model will be performed, including the experimental group and the randomization stratification factor. The hazard ratio and its 95% confidence interval between the two groups will be presented.

Statistical significance will be determined by a P-value of < 0.05.
From enrollment to 1 year
side effects related to medication or other treatments
Time Frame: From enrollment to 1 year
From enrollment to 1 year

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Atrial fibrillation effect on quality-of-life questionnaire score
Time Frame: From enrollment to 1 year
Atrial fibrillation effect on quality-of-life questionnaire scale 0 to 100 Score ranges from a minimum of 0 to a maximum of 100. A higher score indicates a worse outcome.
From enrollment to 1 year
cardiovascular death, cerebral infarction, hospitalization due to heart failure aggravation
Time Frame: From enrollment to 1 year

Individual events and composite events will be presented using frequencies and percentages.

Cox proportional-hazards model will be performed, including the treatment group and the randomization stratification factor. The Log-rank test will be used to compare the incidence rates and hazard ratios between the experimental and active comparator groups.
From enrollment to 1 year
NTproBNP(pg/ml)
Time Frame: From enrollment to 1year
Measured in pg/mL
From enrollment to 1year
Korean Montreal Cognitive Assessment (K-MoCA)
Time Frame: From enrollment to 1 year
Korean Montreal Cognitive Assessment (K-MoCA) score 0 to 30. Score ranges from a minimum of 0 to a maximum of 30, where higher scores indicate better cognitive performance.
From enrollment to 1 year
Left ventricular ejection fraction(LVEF)
Time Frame: From enrollment to 1 year
LVEF in percentage as measured by echocardiography
From enrollment to 1 year
Diastolic function assessment
Time Frame: From enrollment to 1year
Calculate the E/e' ratio using the early diastolic filling velocity (E) and the early diastolic mitral annular velocity (e'), both measured in m/s.
From enrollment to 1year

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Samsung Medical Center

Collaborators

Asan Medical Center
Korea University Anam Hospital
Korea University Guro Hospital
The Catholic University of Korea
Keimyung University Dongsan Medical Center
Wonju Severance Christian Hospital
Inje University Ilsan Paik Hospital
Sinchon Severance Hospital, Yonsei University College of Medicine

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 2, 2024

Primary Completion (Estimated)

December 15, 2027

Study Completion (Estimated)

December 31, 2029

Study Registration Dates

First Submitted

November 23, 2025

First Submitted That Met QC Criteria

February 27, 2026

First Posted (Actual)

March 3, 2026

Study Record Updates

Last Update Posted (Actual)

March 3, 2026

Last Update Submitted That Met QC Criteria

February 27, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • SMC2023-07-195
  • KCT0009027 (Other Identifier: Korea National Institute of Health)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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