Electrical/pharmacological cardioversion improves structural remodeling of left atrium. We hypothesize that persistent atrial fibrillation (AF) patients with more significant left atrial size reduction after cardioversion have lower AF recurrence rates following radiofrequency ablation. The aim is to evaluate the relationship between changes in left atrial size 3 to 6 months after cardioversion and the recurrence rate of atrial fibrillation following radiofrequency ablation.

Background: Atrial fibrillation (AF) is estimated to affect over 33 million people worldwide and 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, which is defined as sustained AF for > 7 days. 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 persistent 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. In AF patients who did not experience AF recurrence after catheter ablation, the reduction in left atrial size was more significant. In the past, a 15% reduction in left atrial volume has been defined as left atrial reverse remodeling and is associated with the maintenance of sinus rhythm after AF ablation. It remains unclear whether the reduction in left atrial size after the restoration of sinus rhythm through electrical or pharmacological cardioversion in patients with persistent AF can predict AF recurrence following radiofrequency ablation.

Objectives: To evaluate the relationship between changes in left atrial size 3-6 months after electrical or pharmacological cardioversion in patients with persistent AF and AF recurrence within one year following radiofrequency ablation.

Methods: This study will be an observational trial of patients with persistent AF. Candidates will be identified among inpatients or outpatients if they have had at least two echocardiograms, one before and one 3-6 months after pharmacological or electrical cardioversion. Heart rhythm will be assessed through medical records and telephone surveys.

Inclusion Criteria:

1. Patients with estabolished diagnosis of Persistent Atrial Fibrillation during past 6 mnths.
2. LAD brfore entering the two cohorts is more than 40mm, and less than 50mm.
3. Pharmacological or electrical cardioversion has be performed successfully.
4. At least two echocardiograms were performed before and 3-6 months after cardioversion., and confirm the status of LAD (Reversal, unchange, enlargment).
5. Patients have given informed consent.

Exclusion Criteria:

1. Prior radiofrequency ablation treatment for atrial fibrillation
2. Prior cardiac surgical procedures
3. Individuals with cognitive impairments who are unable to give informed consent

Persistent atrial fibrillation patients with enlarged left atrium.