It is the purpose of the study to show the benefit of the endocardial catheter ablation by pulmonary vein isolation in patients with persistent or longstanding persistent atrial fibrillation, low LVEF and requiring ICD or CRT-D therapy compared to the best medical treatment with antiarrhythmic drugs.

Atrial fibrillation is the most common sustained cardiac arrhythmia affecting 5% of people older than 65 years. It is associated with a 5 times increase of the risk of stroke in patients who are not receiving anticoagulant therapy and a doubling of the rate of death in all patients.

Congestive heart failure (CHF) and atrial fibrillation (AF) often co-exist, where one condition is promoting the development of the other and worsens its condition.

It is the purpose of the study to show the benefit of the endocardial catheter ablation by pulmonary vein isolation in patients with persistent (for a minimum of 1 week to a maximum of 1 year duration) or longstanding persistent (for a minimum of 1 year to a maximum of 4 years) atrial fibrillation, low LVEF (<=35%) and requiring ICD or CRT-D therapy compared to the best medical treatment with antiarrhythmic drugs.

Patients meeting the inclusion and exclusion criteria will be randomized in a 1:1 fashion in an unblinded, parallel arm treatment format to either drug therapy (directed at rate or rhythm control) or catheter ablation.

All therapies will be established and optimized in a 3 month treatment initiation phase (Blanking Period) starting with randomization. For all morbidity and mortality end-points, intention-to-treat analysis will begin at randomization. Efficacy with respect to AF treatment will be established for long-term follow up beginning after 3-month initiation phase.

Improvement of LVEF within 12 month is the primary endpoint of this study. The transthoracic echocardiographic (TTE) assessment at enrollment, discharge and 12 months follow-up follows a standardized protocol. The assessments are analyzed, calculated and expressed by an independent Core Lab.

Inclusion Criteria:

• Having signed and dated Patient Informed Consent
• Having an indication for ICD or CRT-D therapy as indicated by current valid guidelines or having been implanted with an ICD or CRT-D
• Symptomatic atrial fibrillation (persistent AF (for a minimum of 1 week to a maximum of 1 year) or longstanding persistent AF (for a minimum of 1 year to a maximum of 4 years)) irrespective of the duration of paroxysmal AF
• Ejection fraction ≤ 35% as assessed by transthoracic echocardiography
• Left atrial diameter of less than 60 mm in parasternal diameter during transthoracic echocardiographic study
• ECG documentation of atrial fibrillation (ECG, Holter, event recorders, etc) related to symptomatic episodes
• Having typical symptoms of heart failure NYHA II - III
• Patients > 30 days under optimal medical treatment for heart failure and CRT therapy in case of a pre-implanted CRT-D device
• Age 18 - 75 years
• Willing to participate in randomized trial
• Willing and able to participate in 12 months follow-up period

Exclusion Criteria:

• Longstanding persistent (> 4 years history) or paroxysmal atrial fibrillation
• Having a previously implanted pacemaker
• Having underlying valvular heart disease unless the disease has been corrected
• Patients with acute myocardial infarction
• Patients who have had previous pulmonary vein isolation procedures
• Patients with atrial fibrillation secondary to a reversible cause
• Known presence of intracardiac or other thrombi
• Pregnant females or those of child bearing potential who have not had a negative pregnancy test within 48 hours before treatment
• Patients with other medical condition (i.e., cancer, alcoholism, drug abuse) that may cause the patient to be non-compliant with the protocol, confound the data interpretation or is associated with limited life-expectancy (i.e., less than one year)
• History of bleeding diathesis or suspected pro-coagulant state
• Contraindication to anticoagulation therapy