Mostbauer H, Nishkumay O, Rokyta O, Vavryniuk V. Warfarin resistance: possibilities to solve this problem. A case report.
J Int Med Res 2022;
50:3000605221103959. [PMID:
35748017 PMCID:
PMC9235305 DOI:
10.1177/03000605221103959]
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Abstract
Effective prevention of thromboembolism is essential for patients with mechanical
prosthetic heart valves. For this group of patients, vitamin K antagonists (VKAs) remain
the drug group of choice despite the widespread use of new anticoagulants in other
diseases. As a consequence, warfarin resistance remains a serious challenge for
physicians. The current report describes a 65-year-old male patient that had a mechanical
prosthetic aortic valve implanted due to severe aortic insufficiency after infective
endocarditis. Despite consistent increases in his warfarin dose, the level of
international normalized ratio (INR) remained very low. The patient was considered to have
warfarin resistance. Warfarin was successfully replaced by another VKA, acenocoumarol,
which resulted in a stable INR observed over 1 year of follow-up. Achieving the target INR
in patients with mechanical prosthetic heart valves using VKAs is the main goal of
thromboprophylaxis. Although the genetic changes that cause warfarin resistance are
understood, the options to overcome these pharmacogenetic issues remain limited. Based on
the success with this current patient, physicians with similar patients with warfarin
resistance might wish to consider replacing warfarin with acenocoumarol.
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