ObjectiveTo evaluate the quality of warfarin anticoagulant therapy in patients with stable stage after mechanical valve replacement surgery, to observe the effect of compound salvia miltiorrhiza tablet on the anticoagulant effect of warfarin in patients after mechanical valve replacement, and to understand the impact of genetic polymorphisms of VKORC1, CYP2C9 and CYP4F2 on warfarin resistance in patients with mechanical valve replacement in the stable period.MethodsFrom July 2011 to February 2014, 1 831 patients who had ≥ 6 months after mechanical valve replacement surgery were enrolled at the outpatient follow-up. The basic clinical data were recorded. Anticoagulant therapy uses a target international normalized ratio（INR, 1.60–2.20) and a weekly warfarin dose adjustment strategy. Forty-six patients who needed compound salvia miltiorrhiza tablet were screened and the INR values. Before and after taking tablets were recorded and compared. The patients were divided into three groups according to the percentile of warfarin dosage including a warfarin sensitive patients group, a control patients group, and a warfarin resistance patients group. And 101 of them were selected. TIANGEN blood DNA Kit blood genomic DNA extraction kit was used to extract samples and polymerase chain restriction fragment length polymorphism (PCR-RELP) was used to determine the genotypes of patients. The detected gene loci included CYP4F2: rs2108622C>T locus; VKORC1:1639G>A locus; VKORC1:1173C>T locus; CYP2C9*2: rs1799853C>T locus; CYP2C9*3:1061A>C locus.ResultsThe time in therapeutic range (TTR) and fraction of time in therapeutic range (FTTR) in the target INR range of the patients included in the study period was 27.2% and 49.4%, respectively, and the TTR and FTTR in the acceptable INR range was 34.25% and 63.36%, respectively. Before and after the addition of compound salvia miltiorrhiza tablets, the INR value was 1.55±0.03 and 1.69±0.30, respectively, and the difference was statistically different (P<0.05). A total of 101 patients with genetic testing, in which the C/T composition of the VKORC1: 1173C>T locus increased in the warfarin sensitivity, contrast and warfarin resistance patients, while the ratio of allelic loci of C/T in CYP2C9*3: 1061A>C loci decreased in turn. There was no difference in the CYP4F2 gene, VKORC1639 gene, and CYP2C9*2 locus. The IWPC model predicts that warfarin dose is only consistent with the actual warfarin dose in warfarin sensitive patients.ConclusionRelatively low TTR and FTTR are acceptable in patients with stable stage after mechanical valve replacement. It is beneficial to the patients with compound salvia miltiorrhiza tablets in terms of some appropriate patients. VKORC1: 1173C>T site and CYP2C9*3: 1061A>C site mutation is the main pharmacological gene factor of warfarin dose sensitivity and warfarin resistance in stable period after mechanical valve replacement. The IWPC dose prediction model is only consistent with the actual dose of warfarin sensitive patients.