Should warfarin be routinely prescribed for the first three months after a bioprosthetic valve replacement?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether warfarin should be routinely prescribed for the first three months after a bioprosthetic valve replacement either for the aortic or mitral position. Altogether 620 papers were identified using the below-mentioned search. In addition, all major international guidelines were included. Fifteen papers presented the best evidence to answer the clinical question. The author, journal, date and country of publication, patient group, relevant outcomes and weaknesses were tabulated. We conclude that all guidelines, the available evidence and current practice support the use of warfarin at an INR of 2-3 for 3 months for bioprosthetic mitral valve replacement (MVR). However, it must be acknowledged that this recommendation is based on only a small number of non-randomized cohort studies and on expert consensus. For patients without high risk factors undergoing a bioprosthetic aortic valve replacement (AVR), the European Society of Cardiology (ESC), the American College of Chest Physicians (ACCP) and the Scottish Intercollegiate Guidelines Network (SIGN) all recommend warfarin for 3 months after surgery. However, the American Heart Association (AHA/ACC) guidelines and the British Society for Haematology (BSH) regard aspirin alone as adequate therapy. In addition, two large surveys show that the majority of surgeons worldwide now use only antiplatelet therapy. The evidence from clinical studies to support the use of warfarin post-bioprosthetic AVR is very weak and out-dated, and therefore, we feel that it is certainly safe to use antiplatelet therapy alone post-bioprosthetic AVR.