The main objective of this study is to realize an observational "real life" study conducted in French geriatric settings, to assess safety and efficacy in ≥ 80 year-old patients with nonvalvular Atrial fibrillation (AF) newly treated with Apixaban.

Moreover, in this geriatric population the adequacy of Apixaban dosage and events (bleeding and stroke) will be assessed.

It is a muliticentric, observational, prospective study.

This study will be conducted in about 40 geriatric settings in France.

The planned duration of the inclusion period is 27 months in each center.

The follow-up period starts from inclusion up to one year after inclusion with phone contact or unscheduled visit at 3, 6, 9 and 12 months.

During this follow-up, participants physicians will record patients' data during visit directly from the patients or their physicians or their families and by phone.

The following data will be colllected:

• At M0 : Socio-demographics, clinical and biological data; embolic risk and emorrhagic risk scores,cognitive function, number of falls, blood pressure, nutritional assessment, athonomy, comorbidities, data on anticoagulant therapy, treatment discontinuation and clinical evaluation.
• At M3, M6, M9 and M12: • Number of falls, all treatment schedule, record of major bleeding events, record of any other bleeding events, record of other serious events, record of other non-major events, treatment discontinuation, and social and medical environment.
• Only M6 and M12: Renal function (both Cockcroft-Gault, chronic Kidney Disease, epidemiology Collaboration "CKD EPI" and the four variable modification of Diet in renal Disease equation "MDRD")

Inclusion Criteria:

• Male or female patients aged 80 years and older.
• Patients with non-valvular atrial fibrillation (documented on electrocardiography or other medical evidence like medical chart, hospital discharge note, physician's letter within 3 years before enrollment).
• Followed in geriatric settings (office consultation, acute care, rehabilitation settings and nursing homes).
• Newly treated (less than 6 months) with Apixaban (5mg twice daily (or 2.5 mg twice daily for patients with 2 of the following criteria : age > 80 years, creatinine > 133 μmol/l, weight < 60 kg)

Exclusion Criteria:

• Patient refusing to participate.
• Participation to a clinical trial.
• Contraindication to use of Apixaban as described in the Summary of Product Characteristics .

Patients newly treated with Apixaban for non-valvular atrial fibrillation (no mechanical heart valves, no known moderate or severe mitral stenosis)