Stepwise Strategy for Treatment of Atrialfibrillation Substrate Study

Background: Atrial fibrillation (AF) is associated with significant co-morbidities such as embolic stroke, heart failure, dementia. Consequently, AF poses a significant burden to the healthcare system, in both direct and indirect costs. The management of AF is complex, especially for patients with persistent AF. It is preferable to terminate the AF and restore normal sinus rhythm for relief of symptoms associated with AF or improvement of cardiac structure and function. The maintenance of AF, especially persist AF is associated with fibrosis of left atria. Furthermore, AF itself promotes fibrosis, which in turn leads to increased conduction heterogeneity within the atrial substrate resulting in further progression of AF. In animal models, alterations in myocytes after sustained AF resemble those of myocardial hibernation. Ultimately, these structural changes would lead to Calcium overload and metabolic stress, similar changes have been observed in humans. In humans, atrial dilatation and degenerative changes have been observed. Interstitial fibrosis is the prime cause of structural remodeling in left atrium. Whether reversal of sinus rhythm can reverse fibrosis partly? The introduction of Late Gadolinium enhancement magnetic resonance imaging (LGE-MRI) sequence now allows for non-invasive and dynamic assessment of the location and extent of atrial fibrosis.

The investigators propose to evaluate whether sacubitril/valsartan can reduce atrial fibrillation recurrence rates, improve cardiac structure and function, and analyze the factors influencing the maintenance rate of sinus rhythm after atrial fibrillation ablation.

Objectives:

Primary: In patients with persistent atrial fibrillation and left atrial enlargement, the first part: after drug or electrical cardioversion, on the basis of using amiodarone to maintain sinus rhythm, they were divided into the group prescribed sacubitril/valsartan and the control group, and evaluated whether sacubitril/valsartan could reduce the recurrence rate of atrial fibrillation, improve cardiac structure and function, and improve atrial fibrosis by comparing the maintenance rate of sinus rhythm after cardioversion, ultrasound assessment of atrial structure and function, cardiac MRI evaluation of cardiac structure, function and fibrosis.

The second part: Combined with the patient's wishes, researchers perform annular pulmonary vein isolation 3 to 6 months after cardioversion, evaluate the patient's sinus rhythm maintenance rate and cardiac structure and function at 3 months, 6 months, 1 year and 2 years after ablation. Then we will evaluate whether the improvement of atrial structure and function before surgery can predict the success rate of surgery, and evaluate whether sacubitril/valsartan further improves the success rate of surgery compared with the control group. If the number of patients in the subgroup is sufficient, subgroup analysis can be performed in a specific patient subgroup。

Secondary:

We will assess the effects on patients with the following outcomes, including: analysis of other factors influencing left atrial remodeling. The influencing factors will be analyze of sinus rhythm maintenance rate after other electrical cardioversion.If the number of patients in the subgroup is sufficient, subgroup analysis can be performed in a specific subgroup of patients

Inclusion criteria

Aged 18-80 years, with persistent atrial fibrillation complicated by left atrial enlargement (left atrial anteroposterior diameter 40-50mm); Having the willingness to undergo atrial fibrillation cardioversion and planned to receive amiodarone for pharmacological cardioversion; Having signed a written informed consent form for participation in the study; Not concurrently participating in any other interventional studies.

Exclusion criteria

Females who are pregnant, lactating, or planning to have children within the next 2 years; Patients whose arrhythmia fails to convert to sinus rhythm with medication and who refuse electrical cardioversion; Patients whose arrhythmia cannot be converted to sinus rhythm with either medication or electrical cardioversion; Glomerular filtration rate (eGFR) < 30 ml/min/1.73m² (calculated by the CKD-EPI formula); Patients with biliary cirrhosis or cholestasis; Hyperthyroidism; A history of bradycardia (heart rate < 50 beats/min) or atrioventricular block of second degree or higher; Sick sinus syndrome; Known allergy to iodine, amiodarone, or any of its excipients; Concomitant use of other drugs that prolong the QT interval, or a history of torsades de pointes; Contraindications to atrial fibrillation cardioversion, such as cardiac thrombosis or contraindications to anticoagulation;

A history or current presence of the following diseases or conditions:

• Moderate to severe rheumatic heart disease, valvular heart disease; a history of atrial-related surgery, including valve replacement, radiofrequency ablation for atrial fibrillation/atrial tachycardia/atrial flutter, atrial septal defect occlusion, or complex congenital heart disease surgery;
• A history of myocardial infarction, unstable angina, syncope, or cerebrovascular accident within 3 months;
• NYHA Class III-IV congestive heart failure or EF < 40%;
• Patients judged by the investigator to have poor compliance, inability to complete the study as required, or an expected lifespan of less than 1 year.