Apixaban Safety and Therapy Adherence in Patients With Atrial Fibrillation

The aim of this observational study is to evaluate safety and therapeutic adherence during anticoagulant prophylaxis with apixaban in patients with nonvalvular atrial fibrillation. The main questions it aims to answer are: * What is the incidence of major bleeding and clinically relevant non-major bleeding during anticoagulant prophylaxis with apixaban in patients with nonvalvular atrial fibrillation? * What is therapy adherence during anticoagulant prophylaxis with apixaban in patients with nonvalvular atrial fibrillation? * What is frequency and types of other adverse reactions, excluding bleeding, during anticoagulant prophylaxis with apixaban in patients with nonvalvular atrial fibrillation? Participants will be followed for six months through four measurements. The first and fourth measurements will be performed in person, while the remaining measurements can also be recorded by telephone, if the patient's condition allows. Any bleeding or serious adverse reactions to the medication being administered will be recorded immediately, through unscheduled measurements. Adverse reactions will be recorded at each measurement. Adherence to the medication being administered will be evaluated using the BARS scale.