Abstract 16798: Patterns of Anticoagulation following Bioprosthetic Valve Implantation: Observations from ANSWER
Background: The American College of Cardiology/American Heart Association (ACC/AHA) guidelines recommend warfarin for 3 months following bioprosthetic valve replacement (BVR), yet strong evidence supporting this recommendation is lacking, making process variation likely.
Methods: The ANSWER Registry enrolled 386 patients receiving EPIC or BIOCOR BVRs from May 2007 to August 2008 at 42 centers. Patterns of discharge anticoagulation and outpatient INR values were collected. Mortality, embolic, and bleeding events were assessed to six months post-BVR.
Results: The median patient age was 74 years (IQR, 67 to 80), 39% were female, and 65% were classified as high thromboembolic risk. Warfarin was prescribed in 38% of all BVR patients and 49% in those with high thromboembolic risk. The median time-to-therapeutic INR was 9 days (IQR, 1 to 18), with 20% never reaching therapeutic levels. Among those achieving a therapeutic INR, 78% and 57% had at least one subtherapeutic or supratheraputic INR during subsequent follow-up to 3 months. In follow-up, patients treated with warfarin had similar rates of embolic events (2.8% vs. 3.1%, p=0.884), but substantially higher bleeding incidence than those not treated with warfarin (12.3% vs. 3.1%, p=0.0012). Among patients who were anticoagulated, those with supratheraputic INRs had a seven-fold higher risk for overt bleeding events (25.9% vs. 3.1%).
Conclusions: Anticoagulation strategies following BVR are highly variable and often do not follow recommendations. Challenges in achieving and maintaining therapeutic warfarin anticoagulation are common and associated with increased bleeding risk. Further work to clarify the optimal post-BVR anticoagulation strategy is needed.
- © 2010 by American Heart Association, Inc.