Atrial fibrillation (AF) is the most common cardiac arrhythmia with a lifetime risk of developing AF of 1 in 4 people aged over 40. Stroke remains the most feared complication of AF with an increase in risk by 5-fold, and is the leading cause of morbidity and mortality. The left atrial appendage (LAA) is the origin for more than 90% of the emboli in non-valvular AF. The WATCHMAN™ Left Atrial Closure Device (WATCHMAN Device, Boston Scientific) reduces the risk of stroke by closing off the LAA. During hybrid procedures for AF, LAA occlusion with epicardial devices is known to be difficult and not free of risks.It thus will be interesting to study the safety and feasibility of endocardial WATCHMAN Device implantation in a hybrid ablation approach.

Inclusion Criteria:

• Documented paroxysmal or (long-standing) persistent non-valvular atrial fibrillation,
• Eligible at least for short-term OAC therapy,
• No other conditions that would require long-term OAC therapy, suggested by current standard medical practice, and thus is eligible to stop OAC if the LAA is sealed,
• Calculated CHA2DS2-VASc score of 1 or more,
• 18 years of age or older, able and willing to provide written informed consent.

Exclusion Criteria:

• Current New York Heart Association Class IV Congestive Heart Failure,
• Current thrombocytopenia (< 100x10E9/L) or anemia (hemoglobin <6.2 mmol/L),
• Active infection or sepsis,
• Resting heart rate > 110 beats per minute,
• Cerebrovascular accident (CVA) or transient ischemic attack (TIA) within the last 30 days,
• Recent myocardial infarction (within 3 months),
• Transient case of AF (i.e., secondary to recent cardiac surgery (within 3 months)),
• Planned cardioversion 30 days post implant of the WATCHMAN Device,
• Implanted mechanical valve prosthesis,
• History of obliterated LAA,
• History of heart transplantation,
• Symptomatic carotid disease (i.e., carotid stenosis >50% associated with ipsilateral transient or visual ischemic attack evidenced by amaurosis fugax, ipsilateral hemispheric TIAs or ipsilateral stroke within 6 months),
• Necessity to use long-term OAC,
• Contraindication for use of OAC or dual anti-platelet therapy,
• Contraindication for use of aspirin,
• Pregnancy or planned pregnancy during the course of the investigation,
• Life expectancy less than 2 years,
• Participation in any other clinical study involving an investigational drug or device.

Echocardiographic Exclusion Criteria (as assessed via transthoracic echocardiography (TTE) or TEE) for this study are:

• Left ventricular ejection fraction (LVEF) < 30%,
• Intracardiac thrombus as visualized by TEE within 2 days prior to implant,
• High risk patent foramen ovale,
• Current atrial septal defect and/or previous atrial septal repair or closure device,
• Significant mitral valve stenosis (i.e., MV 4. 5 cm2),
• Existing pericardial effusion of >3 mm,
• Complex atheroma with mobile plaque of the descending aorta and/or aortic arch,
• Cardiac tumor.