To determine the values and limitations of ECGI in guiding ablation and risk stratification in patients with persistent atrial fibrillation.

The patient population will include symptomatic persistent AF patients (N=50). The total of fifty patients will be studied to determine:

• The values and limitations of ECGI in identifying atrial fibrillation (AF) triggers, AF initiators and AF perpetuators as targets sites for catheter ablations in patients with persistent AF.
• The mechanisms of residual atrial tachycardia/flutter (Res-AT/AFl) after AF substrate ablations by targeting complex fractionated atrial electrograms (CFAE).
• If there is a relationship between primary CFAE sites and driver sites or other distinct patterns from the ECGI mapping system.
• The rate of AF termination to sinus rhythm after ablation at target sites identified by ECGI

Inclusion Criteria:

• Patients are diagnosed as persistent AF. Persistent AF was defined as continuous AF from 7 days to 12 months and long- lasting AF beyond twelve months.
• Patients who are symptomatic
• Patients who are willing to sign consent and be followed post procedure in an out- patient arrhythmia clinic

Exclusion Criteria:

• Patients under 18 years or over 85 years of age.
• Patients with chronic alcoholism.
• Recent myocardial infarction within one month of the study.
• Significant debilitating diseases or a terminal disease.
• Patients with documented left atrial thrombus.
• Medical or mental conditions precluding a long-term follow-up.

The patient population will include symptomatic persistent AF patients (N=50). The total of fifty patients will be studied.