The current guidelines in the United States are as follows: Long-term oral anticoagulant therapy is recommended for patients with rheumatic mitral stenosis, mechanical artificial heart valve, and nonvalvular atrial fibrillation with CHA2DS2-VASc scores of ≥ 2 in men and ≥ 3 in women (class of recommendation I) and may be considered for patients with nonvalvular atrial fibrillation and CHA2DS2-VASc scores of ≥ 1 in men and ≥ 2 in women (class of recommendation IIb).