Abstract Number: PB2039
Meeting: ISTH 2020 Congress
Background: Current guidelines recommend targeting an INR of 3.0 (2.5-3.5) in warfarin-treated patients with mechanical aortic valve replacement (AVR) and additional risk factors for thromboembolic events (atrial fibrillation [AF], prior thromboembolism, left ventricular dysfunction, hypercoagulable conditions). A target INR of 2.5 (2.0-3.0) is recommended for mechanical AVR patients without thromboembolic risk factors. However, available literature supporting the higher intensity INR goal in patients with thromboembolic risk factors is lacking.
Aims: Evaluate the efficacy and safety of standard (2.5) versus higher (3.0) intensity anticoagulation in this patient population.
Methods: The six-center Michigan Anticoagulation Quality Improvement Initiative database was used to identify warfarin-treated patients with mechanical aortic valve and at least one additional risk factor. Patients enrolled into the database between November 2009 and March 2019 and followed through May 2019 were included in the analysis. Patients were classified into two groups based on INR goal: standard intensity (INR goal 2.5) versus high intensity (INR goal 3.0). Patients with non-bileaflet AVR or mitral valve replacement were excluded. Regression analysis was used to control for differences in baseline characteristics. The primary outcome was a composite of thromboembolic events, bleeding, or all-cause death.
Results: 373 patients with a mechanical AVR were screened of which 175 in the standard intensity group and 39 in the high intensity group met inclusion. Standard intensity patients were generally older and more likely to be on aspirin. AF was the most common additional risk factor for inclusion, and patients had a mean HAS-BLED score of 2.9 and 2.4 in the standard and high intensity groups, respectively. The primary composite outcome occurred less frequently in the standard intensity group (p=0.002).
Conclusions: Standard intensity anticoagulation resulted in a bleeding reduction while maintaining efficacy compared to higher intensity anticoagulation. These results challenge current guideline recommendations for management of mechanical AVR in patients with additional risk factors.
|Outcomes (# per 100 pt-yr)||Standard Intensity N=175||High Intensity N=39||p-value||Event rate ratio (95% CI)|
|Primary Outcome||17.1||23.4||0.002||0.73 (0.60-0.89)|
|Ischemic/Embolic Stroke||1.0||1.1||1||0.91 (0.35-2.36)|
|ISTH Major Bleed||3.9||6.4||0.02||0.61 (0.40-0.92)|
|ISTH Clinically-Relevant Non-Major Bleed||8.3||8.5||0.94||0.98 (0.72-1.34)|
|Hospitalization (Any)||21.5||21.3||0.96||1.0 (0.83-1.23)|
|RBC transfusion||3.9||7.4||0.001||0.53 (0.35-0.79)|
|Vitamin K administration||3.4||7.4||<0.001||0.46 (0.30-0.70)|
[Outcomes in Standard vs High Intensity INR Target Ranges]
To cite this abstract in AMA style:Hanigan S, Kong X, Haymart B, Kaatz S, Krol G, Shah V, Kozlowski J, Froehlich JB, Barnes GD. Standard Versus Higher Intensity Anticoagulation for Patients with Mechanical Aortic Valve Replacement and Additional Risk Factors for Thromboembolism: A Multi-center Registry Analysis [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/standard-versus-higher-intensity-anticoagulation-for-patients-with-mechanical-aortic-valve-replacement-and-additional-risk-factors-for-thromboembolism-a-multi-center-registry-analysis/. Accessed November 30, 2021.
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