Abstract 16782: Comparative Effectiveness of Wararin Anticoagulation in Older Patients Undergoing Bioprosthetic Aortic Valve Replacement: Results from the Society of Thoracic Surgeons (STS) Adult Cardiac Surgery National Database
Background: Bioprosthetic aortic valve replacement (BVR) carries an early risk of thromboembolic events; however, the safety and effectiveness of discharge anticoagulant strategies is poorly understood.
Methods: We evaluated 3-month clinical outcomes in 25,656 Medicare-linked aortic BVR cases from 2004–06 at 797 hospitals in the Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database. Discharge anticoagulant strategies (aspirin plus warfarin vs aspirin only) were compared using Inverse Probability Weighted (IPW) methods with stratification by age, sex, and thromboembolic risk factor status (RF+, RF-).
Results: At discharge, aspirin only (48.6%) was the most commonly used anticoagulant strategy, followed by aspirin plus warfarin (23.3%), warfarin only (11.7%), dual antiplatelet therapy (8.5%) and no anticoagulant (6.5%). Warfarin was used more often in RF+ than RF- patients (44.1% vs 25.6%). Compared with aspirin only, aspirin plus warfarin was associated with a similar 3-month unadjusted risk of death (RF+, 4.0% vs 3.9% RF-, 1.8% vs 2.2%), a lower risk of ischemic stroke (RF+, 0.7% vs 1.2% RF-, 0.3% vs 0.8% ), and a higher risk of hemorrhage (RF+, 2.9% vs 1.3%; RF-, 2.7% vs 0.7%). Aspirin plus warfarin was associated with a lower adjusted risk of death among RF- (Risk Ratio [RR] 0.65, 95% CI 0.44 to 0.95) and a trend toward lower death among RF+ (0.86, 0.69 to 1.07). Additionally, aspirin plus warfarin was associated with a lower adjusted risk of ischemic stroke (RF+: 0.59, 0.37 to 0.93; number-needed-to-treat [NNT] 203; RF-: 0.37, 0.14 to 0.96; NNT 217) and a higher risk of hemorrhage (RF+: 2.17, 1.60 to 2.94, number-needed-to-harm [NNH] 66; RF-: 4.13, 2.62 to 6.52, NNH 45), although no difference in intracranial hemorrhage was observed. Effects were independent of patient sex, but most pronounced in the oldest (≥75 years) patients.
Conclusions: Despite being recommended by clinical guidelines, warfarin is used in a minority of post-BVR patients. Among the elderly, the addition of warfarin to aspirin is associated with improved survival and reduced ischemic risk at 3 months post-BVR at the expense of an increased risk of non-intracranial hemorrhage.
- © 2010 by American Heart Association, Inc.