Chart 1.

Recommendations for prevention of thromboembolic phenomena in nonvalvular atrial fibrillation

Recommendations	Class	Level of evidence
The CHA2DS2-VASc should be used in all patients	I	B
Patients at low risk, with a CHA2DS2-VASc of zero, have no indication of antithrombotic therapy	I	B
In patients with CHA2DS2-VASc of 1, the antithrombotic therapy may be indicated, taking into consideration the risk of bleeding and patients preferences	IIa	C
Patients with CHA2DS2-VASc ≥ 2 have an indication for antithrombotic therapy	I	A