Optimal Intensity of Warfarin Therapy in Patients With Mechanical Aortic Valves

OBJECTIVE:: To review the current guidelines and published literature in order to identify the evidence-based international normalized ratio (INR) goal in patients with a mechanical aortic valve. DATA SOURCES:: Medline/PubMed, Cochrane and Google Scholar database searches for relevant articles from 1946 through March 2017 were executed using the key words "mechanical aortic valve" and "antithrombotic therapy or anticoagulation therapy or warfarin." STUDY SELECTION AND DATA EXTRACTION:: All English-language observational and interventional studies assessing INR goals in patients with a mechanical aortic valve were evaluated. RESULTS:: After low thrombogenic valves became standard in the practice, the INR goal decreased to 2 to 3 in low-risk recipients with most of bileaflet mechanical aortic valves. There is a paucity of data to justify the INR goal of 2 to 3 in high-risk patients. Until further higher evidence is available, it is reasonable to target an INR range of 2.5 to 3.5 in patients with risk factors for thromboembolism with low thrombogenic valves, except for On-X valve. The INR goal in high-risk On-X aortic valve recipients can be managed at 1.5 to 2.5 with low-dose aspirin 3 months after valve implantation. CONCLUSION:: The INR goals of 2 to 3 for low risk and 2.5 to 3.5 for high risk should be considered for bileaflet mechanical aortic valve recipients. Additionally, a lower INR goal of 2 to 3 for the first 3 months after valve replacement followed by an INR goal of 1.5 to 2.5 in both low- and high-risk aortic On-X valve recipients may be considered.