Warfarin is one of the most frequently prescribed oral anticoagulant. Many researches have shown that the genotypes have been strongly associated with warfarin maintenance doses. Especially, it has been accepted in academia that cytochrome P450 2C9 (CYP2C9) and vitamin K epoxide reductase complex 1 subunit (VKORC1) could affect the warfarin maintenance doses. There are also many other genotypes that were reported to be related to warfarin doses, but the results have been in controversial so far. The studies found that the dose formula which contained the genetic factors and clinical information could accurately predict the maintenance dose of warfarin, however, its usefulness is suspected due to the inconsistent results of clinical trials. Large-sample and multi-center studies are necessary to verify the specific effects of gene and non-gene factors to warfarin dose; at the same time, testing constructed models or building new models help to improve the explained percentages of individual differences.
ObjectivesTo compare different formula calculated dosages with the actual doses of warfarin from patients in Beijing Hospital so as to investigate suitable warfarin dosing models for Chinese patients.MethodsOne hundred and three Chinese patients with long-term prescription of warfarin were randomly selected from Beijing Hospital from July 2012 to May 2013. The CYP2C9 and VKROC1 genotypes and basic statistical information were collected. SPSS 18.0 software was used to compare the differences between different formula calculated dosages and the actual dosages of warfarin.ResultsFive genotypes were found in 103 patients, including: CYP2C9 AA genotype + VKORC1 AA genotype (n=72, 69.9%), CYP2C9 AA genotype + VKORC1 AG genotype (n=17, 16.5%), CYP2C9 AC genotype + VKORC1 AA genotype (n=10, 9.7%), CYP2C9 AC genotype + VKORC1 AG genotype (n=3, 2.9%) and CYP2C9 AA genotype + VKORC1 GG genotype (n=1, 1%). Compared with the actual dosages of warfarin, the degree of coincidence was highest for dosages calculated by Jeffrey’s formula.Conclusions Using Jeffrey’s formula to calculate warfarin dosages may be more suitable for Chinese patients with using long-term warfarin. Due to limited sample size, prospective and large sample size studies are required to verify the above conclusion.
ObjectiveTo investigate the influence of high activity of CYP2C9 (Cytochrome P450 proteins 2C9)and VKORC (Vitamin K epoxide reductase C)on warfarin anticoagulation of patients after heart valve replacement (HVR). MethodsFrom February 2010 to May 2013, 40 patients with high activity of CYP2C9 and VKORC underwent HVR in the Department of Cardiac Surgery, the First Affiliated Hospital of Zhengzhou University. There were 18 male and 22 female patients with their age of 40-51 (45.18±2.93)years. There were18 patients receiving mitral valve replacement (MVR), 14 patients receiving MVR and tricuspid valvuloplasty (TVP), and 8 patients receiving double valve replacement (DVR). Depen-ding on whether they received preoperative genetic polymorphism detection of CYP2C9 and VKORC1, all the patients were divided into 2 groups with 20 patients in each group. Patients in group A didn't receive preoperative genetic polymorphism detection of CYP2C9 and VKORC1, while patients in group B received preoperative genetic polymorphism detection of CYP2C9 and VKORC1. Postoperatively, periodic examination of international normalized ratio (INR)was performed to adjust warfarin dosage. Time to reach expected INR value and morbidity were collected. All the patients were followed up for 3-12 months after discharge. Monthly telephone follow-up was performed to record INR values, morbidity and general recovery. ResultsPostoperatively, in group A, 2 patients had cerebral infarction, 2 patients had popliteal artery throm-bosis, 1 patient had pulmonary embolism, and 1 patient had thrombosis in the annulus. Expected INR was achieved 15-20 days after warfarin treatment among the other 14 patients without thromboembolism. Three months after surgery, CYP2C9 and VKORC1 gene polymorphism was examined to find 17 patients with positive CYP2C9*1/*1 (*2CC/*3AA)and positive VKORC1-1639 GA, and 3 patients with positive CYP2C9*1/*1 (*2CC/*3AA)and positive VKORC1-1639 GG. In Group B, patients received aspirin (100 mg/d)and low molecular heparin (0.4 ml/d)in addition to warfarin since the second posto-perative day. Expected INR was achieved 5-9 days after warfarin treatment, and then aspirin and low molecular heparin were discontinued. During the 6 months follow-up period, no obvious thromboembolism was found, and only 1 patient had epistaxis who was cured with nasal tamponade. ConclusionPreoperative detection of genetic polymorphisms of CYP2C9 and VKORC1 can provide important guidance for warfarin anticoagulation after HVR.
ObjectiveTo systematically review therapy-related complications incidences of warfarin with different anticoagulation intensity in Chinese after mechanical heart valve replacement, and to explore the suitable anticoagulation intensity of warfarin. MethodsWe electronically searched The Cochrane Library (Issue 2, 2013), EMbase, PubMed, CNKI, CBM, WanFang Data and VIP for studies about therapy-related complications rates of warfarin with different anticoagulation intensity in Chinese after mechanical heart valve replacement from inception to March 2013. Two reviewers independently screened literature according to inclusion and exclusion criteria, extracted data, and assessed methodological quality of included studies. Then meta-analysis was performed using RevMan 5.2. ResultsA total of 7 studies involving 3 787 cases were finally included, 2 985 cases in Group A (targeted INR≤2.3) and 802 cases in Group B (targeted INR > 2.3). The results of meta-analysis showed that, compared with Group B, the total therapy-related complications incidence of warfarin with different anticoagulation intensity significantly decreased in Group A (OR=0.35, 95%CI 0.28 to 0.44, P < 0.000 01). The incidence of hemorrhage in Group A (OR=0.15, 95%CI 0.08 to 0.27, P < 0.000 01) was lower than that in Group B. However, the incidence of embolism in Group A was higher than that in Group B (OR=2.77, 95%CI 1.54 to 4.98, P=0.000 7). ConclusionApplying low-intensity anticoagulation for Chinese patients after mechanical heart valve replacement could reduce the overall incidences of anticoagulation-related complications and hemorrhage, but it could also significantly increase the incidence of thrombosis.
ObjectiveTo explore the anticoagulant strategy of adjusting the dose of warfarin at different stages after mechanical valve replacement of mitral valve.MethodsClinical data of a total of 302 patients, including 76 males and 226 females, with an average age of 50.1±10.1 years, who underwent mechanical mitral valve replacement in the Chinese adult cardiac surgery database from 2013 to 2017 were retrospectively analyzed. According to the dose adjustment strategy of taking warfarin, the patients were divided into a D group (adjusting warfarin dose in days) and a W group (adjusting warfarin dose in weeks) to evaluate the anti-coagulation effect of warfarin.ResultsThe total follow-up time was 423277 d (1159.7 years). There was no significant difference in the overall anticoagulant strength, and the warfarin dose adjusted in days was better in the early postoperative period (P<0.05), especially in patients over 60 years. It was better to adjust warfarin dose in weeks in the middle and long periods (P<0.05), especially in patients ≤40 years. In terms of the stability of anticoagulation, it was better to adjust the dosage of warfarin in weeks (P<0.05). It was better to adjust the dosage of warfarin in weeks for early, middle- and long-term anticoagulant therapy after operation (P<0.05), especially in the females aged >40 and ≤50 years.ConclusionWithin the target range of international normalized ratio (1.5-2.5), the anticoagulant strategy of adjusting warfarin dose in days after mechanical valve replacement of mitral valve can achieve a better anticoagulant strength, and adjusting the dosage of warfarin in weeks is better in the middle- and long-term after operation. In general, the anticoagulant effect is more stable in the short term when warfarin dose is adjusted on a weekly basis.
Objective To investigate the influence of CYP2C9 3，VKORC1-1639 G＞A and CYP4F2 rs2108622 genetic polymorphisms on warfarin dosages of patients after heart valve replacement. Methods A total of 133 patients undergoing heart valve replacement in the Department of Cardiovascular Surgery of Fujian Provincial Hospital from November 2011 to August 2012 were included in this study. Polymerase chain reaction（PCR）gene sequencing was performed to detect CYP2C9 3，VKORC1-1639 G＞A and CYP4F2 rs2108622 genetic polymorphism of these 133 patients. Patients were grouped according to their genotypes，and average warfarin dosages were compared between different genotype groups. Results The frequencies of CYP2C9 3 AA，AC and CC were 127 patients，6 patients and 0 patient respectively，and average daily warfarin dosages were 3.75 mg and 2.13 mg respectively which were statistically different between differentCYP2C9 3 genotypes （P＜0.05）. The frequencies of VKORC1-1639 G＞A GG，GA and AA were 3 patients，32 patientsand 98 patients respectively，and average daily warfarin dosages were 6.00 mg，4.50 mg and 3.00 mg respectively which were statistically different between different VKORC1-1639 G＞A genotypes （P＜0.05）. The frequencies of CYP4F2 rs 2108622 CC，CT and TT were 67 patients，59 patients and 7 patients respectively，and average daily warfarin dosages were 3.00 mg，3.75 mg and 4.50 mg respectively which were statistically different between different CYP4F2 rs2108622 genotypes（P＜0.05）. Conclusion CYP2C9 3，VKORC1-1639 G＞A and CYP4F2 rs2108622 genetic polymorphisms are associated with individual difference of warfarin dosages of patients after heart valve replacement.
ObjectiveTo investigate the effect of CYP2C9 and APOE on the dose of stable warfarin and model prediction in Hainan population.MethodsFrom August 2016 to July 2018, 368 patients who required heart valve replacement and agreed to take warfarin anticoagulation at the second department of cardiothoracic surgery in our hospital were enrolled, including 152 males aged 48.5–70.5 (60.03±10.18) years and 216 females aged 43.5–65.6 (54.24±11.35) years. CYP2C9 and APOE were amplified by polymerase chain reaction. The gene fragment was sequenced by the Single Nucleotide Polymorphisms (SNP) site. The patients' age, sex, weight, history of smoking and drinking, and the dose of stable warfarin were recorded. Regression analysis of these clinical data was made to construct a dose prediction model.ResultsAmong 368 patients, CYP2C9 genotype test results showed 301 patients (81.8%) with *1*1 genotype, and 67 patients (18.2%) with *1*3 type. For different CYP2C9 genotype patients, the difference was statistically significant in the dose of stable warfarin (P<0.05). The results of APOE genotype showed 93 patients (25.3%) with E2 genotype, 221 patients (60.1%) with E3 genotype, and 54 patients (14.7%) with E4 genotype; the dose of stable warfarin in patients with different APOE genotypes was statistically significant (P<0.05). Multiple regression analysis showed that patients' age, body weight, and CYP2C9 and APOE genotypes were correlated with the dose of stable warfarin. The correlation coefficient R2 was 0.572, and the prediction model was statistically significant (P<0.05).ConclusionCYP2C9 and APOE gene polymorphisms exist in Hainan population. There is significant difference in the dose of stable warfarin among different genotypes of patients. The model to predict stable warfarin can partly explain the difference of warfarin among different patients.
Objective To systematically review the effect of discontinuous warfarin on the risk of postoperative bleeding complications after tooth extractions. Methods PubMed, EMbase, The Cochrane Library (Issue 9, 2016), CNKI, VIP, WanFang Data, China Food and Drug Administration and the ADR supervision system of FDA were electronically searched to collect randomized controlled trials (RCTs) and cohort studies about the effect of discontinuous warfarin on risk of postoperative bleeding complications after tooth extractions in patients until September 30th, 2016. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies. Then, meta-analysis was performed using RevMan 5.3 software. Results A total of 8 studies were included, involving 3 RCTs and 5 cohort studies. The results of meta-analysis showed that: there was no significant difference between the discontinuous or reduced warfarin group and the continuous warfarin group (RCTs: RR=0.86, 95%CI 0.49 to 1.51,P=0.60; cohort studies: RR=0.67, 95%CI 0.45 to 1.01,P=0.06). Conclusions Current evidence indicates that there is no statistically significant correlation between whether discontinuous warfarin and the risk of postoperative bleeding complications after tooth extractions. Due to the limited quantity and quality of included studies, the above conclusions are needed to be further verified by more high quality studies.
Warfarin is one of the most frequently prescribed oral anticoagulant. Many researches have shown that the cytochrome P450 2C9 (CYP2C9) and vitamin K epoxide reductase complex 1 (VKORC1) genotypes have been strongly associated with warfarin maintenance doses. Warfarin maintenance doses can be accurately predicted by use of dosing algorithms including genetic and clinical information. Although several clinical trials demonstrated mixed results, calling into question the utility of this approach. The present data do not support genetic testing to guide warfarin maintenance doses, but in the setting where genotype data are available, use of this approach is reasonable. Ongoing trials are expected to provide more data, and more work is needed to define dosing algorithms that include appropriate variables in minority populations. All these work will further improve the clinical application of genotype-guided warfarin maintenance doses.
Objective To evaluate the long-term anticoagulation outcomes of target international normalized ratio (INR) 1.60 to 2.20 and weekly dosage adjustment of warfarin in patients after mechanical heart valve replacement. Methods Outpatients after mechanical heart valve replacement at least 6 months were registered continually from July 2011 to July 2016 in department of cardiothoracic surgery at Zigong No.4 People's Hospital and West China Hospital. There were 1 690 females (70.62%) and 703 males (29.38%) with a median age of 47 years, ranging from 14 to 80 years. All patients were followed up for 6-61 months. Target INR was 1.60 to 2.20 and warfarin dosage were adjusted weekly. Unexpected bleeding, thrombogenesis and thromboembolism, time in therapeutic range (TTR) and fraction of TTR (FTTR) were recorded and calculated to evaluate the outcome of anticoagulation management. Results A total of 2 393 patients with 26 521 INR values were included for data analysis. INR values varied from 0.90-8.39 (1.82±0.45) and required weekly doses of warfarin were 1.75-61.25 (21.72±7.39) mg. TTR of target INR and acceptable INR was 59.38% (1 449 514.0 days/2 441 060.0 days) and 73.57% (1 795 971.0 days/2 441 060.0 days), respectively. FTTR of target INR and acceptable INR were 50.71% (13 450 times/26 521 times), 65.25% (17 305 times/26 521 times). During the follow-up , anticoagulation-related complications included: cerebral infarction in 21 patients (complete recovery in 18 patients, physical activity disorder in 3 patients), cerebral hemorrhage in 4 patients (death in 1 patient, complete recovery in 3 patients), severe gastrointestinal bleeding in 3 patients (completely recovered) and uterine bleeding in 1 patient (surgical removal of the uterus). Conclusion Target INR 1.60–2.20 and warfarin weekly dosage adjustment for patients after mechanical heart valve replacement is reasonable and safe.