A Dose-range Finding Study of MAA868 in Patients With Atrial Fibrillation

Inclusion Criteria: * Male and female patients ≥ 18 and \< 85 years old with paroxysmal atrial fibrillation (PAF) or atrial flutter on 12 lead electrocardiography at Screening Or * Patients with a history of PAF or atrial flutter, as documented by (telemetry, 12 lead electrocardiography or ambulatory \[e.g. Holter\] monitor) and not due to a reversible condition (e.g. alcohol binge drinking) can be entered even if they do not have PAF at Screening. There is not time-limit for this. * Patients with a Congestive heart failure, Hypertension, Age ( \> 65 = 1 point, \> 75 = 2 points), Diabetes, previous Stroke/transient ischemic attack (2 points) (CHA2DS2-VASc) risk score (tool as a predictor for estimating the risk of stroke in patients with atrial fibrillation (AF); Lip et al 2010) of 0-1 for men and 1-2 for women and in whom, in the investigator's judgment, the use of an anticoagulant for stroke prevention is not indicated Exclusion Criteria: * History of stroke, transient ischemic attack or systemic embolism * History of major bleeding during treatment with an anticoagulant or antiplatelet therapy. (Patients who have had major bleeding on anticoagulants or antiplatelet therapy more than a year ago can be enrolled only if the bleeding was due to a reversible cause, e.g. gastro-duodenal ulcer that was successfully treated.) * History of traumatic or non-traumatic intracranial, intraspinal or intraocular bleeding * Known bleeding diathesis or any known active bleeding site at screening or baseline * Family history of bleeding disorder * Known active GI lesions predisposing to bleeding events * Myocardial infarction, unstable angina pectoris or coronary artery bypass graft (CABG) surgery within 12 months prior to the Screening period * Known clinically significant valvular heart disease including moderate or severe mitral stenosis (valve area \<1.5 cm2) * Patients with a prosthetic heart valve Other protocol defined Inclusion/Exclusion criteria may apply