Atrial high-rate episodes (AHREs) detected by cardiac implantable electronic devices (CIEDs) are associated with an increased risk of progression to clinical atrial fibrillation (AF), stroke, heart failure, and mortality. However, optimal management strategies for patients with AHREs lasting between 6 minutes and 24 hours remain uncertain. Current guidelines recommend risk factor modification, but the role of early rhythm-control therapy in preventing AHRE progression has not been well established.

This prospective, randomized, open-label study aims to evaluate whether a rhythm-control strategy combined with optimal risk factor management can reduce progression to sustained AHREs (≥24 hours) or clinical AF compared with optimal risk factor management alone in patients with device-detected AHREs. Eligible participants with CIED-detected AHREs lasting 6 minutes to 24 hours and without prior clinical AF will be randomly assigned to either a rhythm-control group or a usual-care group. The primary endpoint is progression to AHRE duration ≥24 hours or documented clinical AF. Secondary endpoints include stroke, systemic embolism, heart failure hospitalization, cardiovascular death, and all-cause mortality.

Atrial high-rate episodes (AHREs) detected by cardiac implantable electronic devices (CIEDs) are increasingly recognized as an early stage of atrial fibrillation (AF) and are associated with an elevated risk of AF progression, stroke, heart failure, and mortality. However, the optimal management of patients with device-detected AHREs remains uncertain, particularly for individuals with episodes lasting between 6 minutes and 24 hours. Current management strategies generally focus on risk factor modification and clinical surveillance, while evidence supporting early rhythm-control intervention in this population is limited.

Observational studies have demonstrated that progression from shorter-duration AHREs to sustained AHREs (≥24 hours) is associated with substantially worse clinical outcomes and may represent an important stage in the evolution of atrial cardiomyopathy. Preventing progression of AHREs may therefore provide an opportunity to alter the natural history of AF and reduce future cardiovascular complications.

This prospective, randomized, open-label, controlled trial is designed to evaluate whether an early rhythm-control strategy can reduce progression of device-detected AHREs compared with usual care. Eligible participants are adults with CIED-detected AHREs lasting between 6 minutes and 24 hours and without a prior diagnosis of clinical atrial fibrillation. Participants will be randomly assigned in a 1:1 ratio to either a rhythm-control strategy or usual care.

The rhythm-control strategy may include antiarrhythmic drug therapy, catheter ablation, or other guideline-directed rhythm-control interventions at the discretion of the treating physician. Both groups will receive comprehensive management of cardiovascular risk factors according to contemporary clinical practice guidelines.

The primary endpoint is a composite of progression to sustained AHREs (≥24 hours) or development of clinically documented atrial fibrillation during follow-up. Secondary endpoints include changes in AHRE burden, ischemic stroke, systemic embolism, heart failure hospitalization, cardiovascular death, all-cause mortality, and treatment-related adverse events.

Participants will undergo regular device interrogation and clinical follow-up throughout the study period. The study aims to determine whether early rhythm-control intervention can delay AF progression and improve long-term cardiovascular outcomes in patients with device-detected AHREs.

Inclusion Criteria Age ≥18 years. Presence of a cardiac implantable electronic device (CIED), including permanent pacemaker, implantable cardioverter-defibrillator (ICD), or cardiac resynchronization therapy (CRT) device.

Device-detected atrial high-rate episodes (AHREs) lasting ≥6 minutes and <24 hours.

Ability to provide written informed consent. Willingness and ability to comply with study procedures and follow-up visits. Exclusion Criteria Prior diagnosis of clinical atrial fibrillation, atrial flutter, or atrial tachycardia requiring treatment.

Device-detected AHRE ≥24 hours before enrollment. Current treatment with class I or class III antiarrhythmic drugs for atrial arrhythmias.

Previous catheter ablation for atrial fibrillation or atrial flutter. Planned catheter ablation within the next 3 months. Contraindication to rhythm-control therapy as determined by the treating physician.

Life expectancy less than 1 year. Severe comorbid illness that may interfere with study participation or follow-up.

Pregnancy or breastfeeding. Participation in another interventional clinical trial that may affect study outcomes.

De-identified individual participant data that underlie the results reported in publications, including demographic characteristics, baseline clinical variables, device interrogation data, and outcome measures, will be made available upon reasonable request to the corresponding investigator after publication of the primary study results.

Beginning 6 months after publication of the primary results and ending 5 years after publication.

Data will be available to qualified researchers whose proposed use of the data has been approved by the study investigators. Requests should be directed to the corresponding investigator. A data use agreement may be required.