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Richard Whitlock, MD, PhD; Matthew Danter, MD
Author and Funding Information

From the Division of Cardiac Surgery, McMaster University.

Correspondence to: Richard Whitlock, MD, PhD, Division of Cardiac Surgery, McMaster University, 1280 Main St W, Hamilton, ON, L8S 4LB, Canada; e-mail: richard.whitlock@phri.ca


Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2013;143(5):1514. doi:10.1378/chest.13-0557
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To the Editor:

We thank Drs Fu and colleagues for their letter regarding the applicability of the American College of Chest Physicians guidelines on antithrombotic and thrombolytic therapy for valvular disease to Chinese patients. To clarify, the guidelines on mechanical valves recommend the following1:

  • 1. In patients with a mechanical aortic valve, we recommend VKA (vitamin K antagonist) therapy with a target of 2.5 (range, 2.0-3.0) over higher targets (Grade 1B).

  • 2. In patients with a mechanical mitral valve, we suggest VKA therapy with a target of 3.0 (range, 2.5-3.5) over lower international normalized ratio (INR) targets (Grade 2C).

  • 3. In patients with mechanical heart valves in both the aortic and the mitral positions, we suggest target INR 3.0 (range, 2.5-3.5) over target INR 2.5 (range, 2.0-3.0) (Grade 2C).

However, the gist of the letter from West China Hospital is valid. INR targets in Chinese patients, and indeed in all patients, need higher-quality evidence than what currently exists. Differing INR targets based on thromboembolic risk is unique to heart valve therapy; for example, the INR target for a patient with atrial fibrillation and a CHA2DS2VASc stroke risk score of 8 is the same as that of a patient with a CHA2DS2VASc score of 3, despite higher thromboembolic risk.2 The evidence supporting such differing targets for heart valves is of moderate quality at best according to the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) framework,3 and begs for further studies. One such study, Lowering the Intensity of Oral Anticoagulant Therapy in Patients With Bileaflet Mechanical Aortic Valve Replacement (LOWERING-IT), also supports the approach of lower INR targets in low-risk mechanical aortic valves but needs validation in a larger trial.4 The ninth edition of the American College of Chest Physician guidelines presents an objective assessment of the available literature up to October 2009 that is based on the GRADE framework and the resultant recommendations. We look forward to reading publications from the West China Hospital based on its national database and will incorporate any new knowledge into future guidelines.

References

Whitlock RP, Sun JC, Fremes SE, Rubens FD, Teoh KH. Antithrombotic and thrombolytic therapy for valvular disease: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(2)(suppl):e576S-e600S. [CrossRef] [PubMed]
 
You JJ, Singer DE, Howard PA, et al. Antithrombotic therapy for atrial fibrillation: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(2)(suppl):e531S-e575S. [CrossRef] [PubMed]
 
Guyatt GH, Oxman AD, Vist GE, et al; GRADE Working Group. GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. BMJ. 2008;336(7650):924-926. [CrossRef] [PubMed]
 
Torella M, Torella D, Chiodini P, et al. LOWERing the INtensity of oral anticoaGulant Therapy in patients with bileaflet mechanical aortic valve replacement: results from the “LOWERING-IT” trial. Am Heart J. 2010;160(1):171-178. [CrossRef] [PubMed]
 

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References

Whitlock RP, Sun JC, Fremes SE, Rubens FD, Teoh KH. Antithrombotic and thrombolytic therapy for valvular disease: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(2)(suppl):e576S-e600S. [CrossRef] [PubMed]
 
You JJ, Singer DE, Howard PA, et al. Antithrombotic therapy for atrial fibrillation: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(2)(suppl):e531S-e575S. [CrossRef] [PubMed]
 
Guyatt GH, Oxman AD, Vist GE, et al; GRADE Working Group. GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. BMJ. 2008;336(7650):924-926. [CrossRef] [PubMed]
 
Torella M, Torella D, Chiodini P, et al. LOWERing the INtensity of oral anticoaGulant Therapy in patients with bileaflet mechanical aortic valve replacement: results from the “LOWERING-IT” trial. Am Heart J. 2010;160(1):171-178. [CrossRef] [PubMed]
 
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