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The WATCHMAN Left Atrial Appendage Closure Device for Atrial Fibrillation
Published on: February 28, 2012
Patient-specific decision-making for warfarin therapy in nonvalvular atrial fibrillation: how will screening with
Mark H Eckman1, Lawrence K S Wong, Yannie O Y Soo
1Division of General Internal Medicine and the Center for Clinical Effectiveness, University of Cincinnati Medical Center, Cincinnati, Ohio 45267-0535, USA. mark.eckman@uc.edu
Insights
Genetic testing and MRI screening do not currently support withholding warfarin for atrial fibrillation patients. Current risk markers are insufficient to alter anticoagulation strategies for most individuals.
Area of Science:
- Cardiology
- Neurology
- Pharmacogenomics
Background:
- Intracerebral hemorrhage (ICH) is a major complication of warfarin anticoagulation, particularly in atrial fibrillation patients.
- Both ICH and warfarin-related ICH have potential genetic predispositions.
- Advanced MRI techniques can identify individuals at elevated ICH risk.
Purpose of the Study:
- To evaluate if genetic profiling and neuroimaging screening can improve warfarin safety for atrial fibrillation.
- To determine if these strategies can identify patients for whom warfarin should be withheld.
Main Methods:
- A Markov state transition decision model was employed.
- Effectiveness was measured using quality-adjusted life-years.
- Data were sourced from literature searches and institutional data, with a base case of a 69-year-old male with nonvalvular atrial fibrillation.
Main Results:
- Anticoagulation is preferred for average-risk patients even with genetic risk factors, unless ICH risk exceeds 23.8.
- Genetic profiling is beneficial for low thromboembolism risk patients if ICH risk is >4.1.
- Screening with genotyping and MRI did not improve outcomes unless MRI predictive power was high and thromboembolism risk was low to moderate.
Conclusions:
- Current genetic markers for bleeding risk are insufficient to justify routine genetic testing for average-risk patients.
- Existing data do not support using MRI or genotyping to withhold warfarin in atrial fibrillation patients.
Background And Purpose:
Intracerebral hemorrhage (ICH) accounts for a majority of long-term morbidity and mortality associated with bleeding while on warfarin. Both ICH and warfarin-related ICH appear to have a genetic component. Furthermore, advanced neuroimaging using MRI can now identify individuals at increased risk of ICH. We explore whether screening strategies that include genetic profiling and neuroimaging might improve the safety of chronic anticoagulation for atrial fibrillation by identifying individuals from whom warfarin should be withheld.
Methods:
We used a Markov state transition decision model. Effectiveness was measured in quality-adjusted life-years. Data sources included the English language literature using MEDLINE searches and bibliographies from selected articles along with empirical data from our institutions. The base case was a 69-year-old man with newly diagnosed nonvalvular atrial fibrillation.
Results:
For patients at average risk for thromboembolic events and known to possess a hypothetical genetic profile increasing risk for warfarin ICH, anticoagulation remains the preferred strategy until the relative hazard of ICH exceeds 23.8. Genetic profiling would be favored for patients at low risk of thromboembolism (1.5% per year) if the hypothetical gene variant(s) conferred a relative risk of ICH >4.1. Screening strategies in which patients underwent genotyping and MRI before anticoagulation did not improve aggregate patient outcomes unless the predictive power of MRI exceeded current best guess estimates and patients were at low to moderate risk of thromboembolism.
Conclusions:
Currently identified genetic markers of bleeding risk do not confer a risk of ICH sufficiently high to warrant routine genetic testing for patients at average risk of thromboembolism. Even if patients undergo screening with MRI as well as genotyping, currently available data on the role of MRI on risk of ICH and warfarin ICH do not support use of these tests for withholding anticoagulation in patients with atrial fibrillation.
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