Low

Moderate

High

Mechanical heart valve

Mechanical bileaflet aortic valve with no additional stroke risk factors

Mechanical bileaflet aortic valve and one of the following risk factors: AF, history of stroke/TIA, hypertension, diabetes mellitus, congestive heart failure, age >75 years

– Mechanical mitral valve; old-type mechanical aortic valve (caged-ball, tilting-disc)

– History of stroke or TIA in prior 6 months

Atrial fibrillation

CHADS2 score 0-2 and no history of stroke or TIA

CHADS2 score 3-4

– CHADS2 score 5-6

– History of stroke or TIA in prior 3 months

– Rheumatic heart disease

VTE

History of 1 VTE event >12 months ago, currently no other risk factors for VTE

– History of VTE in prior 3-12 months or recurrent VTE

– Milder forms of thrombophilia (eg, heterozygotes for prothrombin G20210A gene or factor V Leiden)

– History of VTE in prior 3 months

– Severe thrombophilia (eg, antithrombin, protein C or protein S deficiency, APS, several coexisting conditions)

– Cancer (treatment in prior 6 months or palliative therapy)

CHADS2 score: see table 3.4-2.