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.