Table 2.

Thrombotic assessment

	Thrombotic risk
	High	Moderate	Low
Mechanical heart valve	Any mechanical mitral valve Older mechanical valve model aortic valve (caged ball/tilting disc) Recently placed mechanical valve (<3 months) Recent stroke or TIA (within 6 months)	Bi-leaflet aortic valve and one of the following: AF, previous stroke/TIA, hypertension, diabetes, heart failure, age >75 years.	Bi-leaflet aortic valve without AF and no other risk factors for stroke
Atrial fibrillation	With mechanical heart valve With rheumatic fever With recent stroke or TIA (<3 months) CHADS score 5 or 6	CHADS score of 3 or 4	CHADS score 0–2 (no previous TIA/Stroke)
Venous thromboembolism	VTE with previous 3 months With severe thrombophilia (Protein C, S or Antithrombin III deficiency, Homozygous factor V Leiden mutation)	VTE 3–12 months ago Recurrent VTE With non-severe thrombophilia (Heterozygous factor V Leiden mutation)	Single VTE >12 months ago and no other risk factors

AF = atrial fibrillation; CHADS = congestive cardiac failure, hypertension, age of 75 years or older, diabetes or previous stroke or TIA; TIA = transient ischaemic attack; VTE = venous thromboembolism.

Adapted with permission from Douketis et al.³³