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Table 51.3

Target (and Range) International Normalized Ratio (INR) for Mechanical Prostheses

Prosthesis thrombogenicityNo patient risk factors*>1 risk factor*
Low2.5 (2.0–3.0)3.0 (2.5–3.5)
Medium3.0 (2.5–3.5)3.5 (3.0–4.0)
High3.5 (3.0–4.04.0 (3.5–4.5)
Prosthesis thrombogenicity:
  • Low: Carbomedics, Medtronic Hall, St Jude Medical, On-X**
  • Medium: other bileaflet valves
  • High: Lillehei-Kaster, Omniscience, Starr-Edwards, Bjork-Shiley and other tilting-disc valves

* Patient-related risk factors: mitral or tricuspid valve replacement; previous thromboembolism; atrial fibrillation; mitral stenosis of any degree; left ventricular ejection fraction <35%.

** The OnX aortic valve has recently received a licence for an INR target 1.8 and range 1.5–2.0.