Development and validation of a mobile application based on a machine learning model to aid in predicting dosage of vitamin K antagonists among Indian patients post mechanical heart valve replacement

Patients who undergo heart valve replacements with mechanical valves need to take Vitamin K Antagonists (VKA) drugs (Warfarin, Nicoumalone) which has got a very narrow therapeutic range and needs very close monitoring using PT-INR. Accessibility to physicians to titrate drugs doses is a major problem in low-middle income countries (LMIC) like India. Our work was aimed at predicting the maintenance dosage of these drugs, using the de-identified medical data collected from patients attending an INR Clinic in South India. We used artificial intelligence (AI) - machine learning to develop the algorithm. A Support Vector Machine (SVM) regression model was built to predict the maintenance dosage of warfarin, who have stable INR values between 2.0 and 4.0. We developed a simple user friendly android mobile application for patients to use the algorithm to predict the doses. The algorithm generated drug doses in 1100 patients were compared to cardiologist prescribed doses and found to have an excellent correlation.

Mechanical heart valve thrombosis during pregnancy under non / 中南大学学报(医学版)

Anticoagulation drugs should be used for patients with mechanical heart valve (MHV) in case of potential risk of thrombosis. Pregnant women with MHV have to change therapies due to teratogenic effect of some anti-coagulation drugs. European Society of Cardiology clinical guidelines for the management of cardiovascular diseases during pregnancy gives specific suggestions for anticoagulation therapy.We have treated 2 patients with mechanical heart valve thrombosis (MVT) during pregnancy: One received low molecular weight heparin (LMWH) throughout the pregnancy and developed MVT at the third trimester of pregnancy; one developed MVT at the first trimester when replacing vitamin K antagonists (VKA) with LMWH. These patients raised secondary reflection on the balance between clinical guideline and personalized medicine. During LMWH therapy, we should dynamically monitor patients' anti-activated factor X (anti-Xa) level to evaluate coagulation function during pregnancy. When a pregnant woman with MHV develops symptoms of acute heart failure, stuck mechanical valve should be paid attention to and surgery should be promptly performed if necessary.

Comparison on efficacy and safety of different bridging anticoagulation therapies in patients undergoing mechanical heart valve replacement surgery / 中华心血管病杂志

Objective@#To evaluate the efficacy and safety of different bridging anticoagulant therapies in patients undergoing mechanical heart valve replacement (MHVR) surgery.@*Methods@#Consecutive patients undergoing MHVR surgery from January 2018 to December 2018 in First Hospital of Lanzhou University were prospectively enrolled in this study. Patients were divided into unfractionated heparin (UFH) group and low molecular weight heparin (LMWH) group according to the postoperative bridging anticoagulation methods. Preoperative clinical data and postoperative related time and cost parameters, including drainage time, duration of stay in intensive care unit (ICU), postoperative time (interval from end of operation to discharge) and INR stabilization time (interval from start of bridge anticoagulation to INR value reaching the standard for 2 consecutive days) of all enrolled patients were collected, and all patients were followed up for 4 weeks and thromboembolic or bleeding events were analyzed. Multivariate logistic regression was used to determine the independent prognostic factors of thromboembolic or bleeding events after MHVR receiving various bridging anticoagulant therapies.@*Results@#A total of 217 patients were included in the study, including 120 patients in the UFH group and 97 patients in the LMWH group. Stroke occurred in two patients in the UFH group, while no stroke event occurred in the LMWH group. The incidence of bleeding events was significantly higher (9.28%(9/97) vs. 1.67%(2/120), P=0.02), while the drainage time, duration of stay in ICU, postoperative time, INR stabilization time were all significantly shorter in LMWH group than in UFH group (all P<0.05). Multivariate logistic regression analysis showed that bridging anticoagulation therapies (OR=0.18, 95%CI 0.04-0.86, P=0.03), fibrinogen level (OR=1.99, 95%CI 1.16-3.41, P=0.01) and creatinine level (OR=1.05, 95%CI 1.01-1.08, P=0.04) were independent prognostic factors for bleeding events.@*Conclusion@#LMWH use is associated with increased risk of bleeding events, but can significantly reduce the drainage time, duration of stay in ICU, postoperative time, INR stabilization time in patients post MHVR surgery.

Comparison on efficacy and safety of different bridging anticoagulation therapies in patients undergoing mechanical heart valve replacement surgery / 中华心血管病杂志

Objective: To evaluate the efficacy and safety of different bridging anticoagulant therapies in patients undergoing mechanical heart valve replacement (MHVR) surgery. Methods: Consecutive patients undergoing MHVR surgery from January 2018 to December 2018 in First Hospital of Lanzhou University were prospectively enrolled in this study. Patients were divided into unfractionated heparin (UFH) group and low molecular weight heparin (LMWH) group according to the postoperative bridging anticoagulation methods. Preoperative clinical data and postoperative related time and cost parameters, including drainage time, duration of stay in intensive care unit (ICU), postoperative time (interval from end of operation to discharge) and INR stabilization time (interval from start of bridge anticoagulation to INR value reaching the standard for 2 consecutive days) of all enrolled patients were collected, and all patients were followed up for 4 weeks and thromboembolic or bleeding events were analyzed. Multivariate logistic regression was used to determine the independent prognostic factors of thromboembolic or bleeding events after MHVR receiving various bridging anticoagulant therapies. Results: A total of 217 patients were included in the study, including 120 patients in the UFH group and 97 patients in the LMWH group. Stroke occurred in two patients in the UFH group, while no stroke event occurred in the LMWH group. The incidence of bleeding events was significantly higher (9.28%(9/97) vs. 1.67%(2/120), P=0.02), while the drainage time, duration of stay in ICU, postoperative time, INR stabilization time were all significantly shorter in LMWH group than in UFH group (all P<0.05). Multivariate logistic regression analysis showed that bridging anticoagulation therapies (OR=0.18, 95%CI 0.04-0.86, P=0.03), fibrinogen level (OR=1.99, 95%CI 1.16-3.41, P=0.01) and creatinine level (OR=1.05, 95%CI 1.01-1.08, P=0.04) were independent prognostic factors for bleeding events. Conclusion: LMWH use is associated with increased risk of bleeding events, but can significantly reduce the drainage time, duration of stay in ICU, postoperative time, INR stabilization time in patients post MHVR surgery.

The study of peer education among discharged patients after mechanical heart valve replacement / 中国实用护理杂志

Objective To explore the effect of peer education among discharged patients after mechanical heart valve replacement. Methods A total of 84 patients undergoing mechanical heart valve replacement in hospital from August to December 2016 were enrolled and randomly divided into two groups, 42 cases in each group. All of the patients received routine discharge guidance and outpatient follow-up after discharge from hospital, based on the same medical treatment, the experimental group were given peer education, and the intervention was provided from one month to six month after discharge, afterwards, anticoagulant knowledge, anticoagulant therapy compliance and complication rates were compared between the two groups discharged the same day, 1 months, 3 months, and 6 months after discharge. Results There was no significant difference in each of the evaluation index between the two groups discharged the same day (P>0.05). The anticoagulant knowledge and anticoagulant therapy compliance of the experimental group were higher than those of the control group at 1, 3, 6 months after the intervention (χ2=6.102, 7.378, 12.210, P<0.05 or 0.01), and the incidence of complications was lower than that of the control group at 6 months after the intervention (χ2=3.859, 5.765, 8.278, P<0.05 or 0.01). At 6 months after intervention, the incidence of complications in the experimental group was lower than that in the control group (χ2=5.486, P<0.05). Conclusion Peer education among discharged patients after mechanical heart valve replacement can improve their anticoagulant knowledge and anticoagulant therapy compliance, and reduce the incidence of complications caused by inappropriate anticoagulation.

Self-management in patients after mechanical heart valve replacement and the influential factors / 中国实用护理杂志

Objective To investigate the current status of self-management in patients after mechanical heart valve replacement(MHVR) and the influential factors. Methods The convenience sampling method was used to obtain the sample in Chongqing Province, and 400 participants after MHVR at a month in 3 top three hospitals were recruited (Department of Cardiothoracic Surgery, the First Hospital of Chongqing Medical University. The Second Clinical Medical College of Third Military Medical University. The Third Clinical Medical College of Third Military Medical University). Self-Management Scale for patients after Mechanical Heart Valve Replacement edited by ourselves were used to collect the data. Results The score of patients were 79-119 (96.81 ± 7.86) points. The influential factors were sex, age, education level and the resident manner. Conclusions The self-management level of patients after MHVR is not so bad, the male, advanced age, live with distant relatives or housemaid, low education level's patients' self-management ability are low, the medical workers should strenghen health education in these patients.

Mediating effect of belief about medicine on correlation between social support and adherence to anticoagulation treatment among patients with mechanical heart valve replacement / 中国实用护理杂志

Objective To explore the relationships among social support , belief about medicine and adherence to anticoagulation treatment,and mediating effect of belief about medicine on the relationship between social support and adherence to anticoagulation treatment among patients with mechanical heart valve replacement. Methods Totally 154 patients were recruited. The social support scale, the modified Chinese Version Morisky Medication Adherence Scale( MMAS-8) and belief about medicine scale were used and the information on patients were collected through clinic and telephone interviews. Results The social support was correlated with belief about medicine (r=0.441, P<0.05). The belief about medicine was correlated with adherence to anticoagulation treatment (r=0.441, P<0.05). The social support was correlated with adherence to anticoagulation treatment (r=0.300, P<0.05) . The mediator effect of the belief about medicine was tested between social support and adherence to anticoagulation treatment. In the result, with the influence of belief about medicine .The social support was not correlated with adherence to anticoagulation treatment ( B=0.020,P>0. 05). Conclusion Belief about medicine plays a completely mediating role in the relation between social support and adherence to anticoagulation treatment.

Research progress on strategies to improve patients′ adherence to anticoagulation with warfarin after mechanical heart- valve replacement / 中国实用护理杂志

It is reviewed in this article that the current situation of patients′ adherence to anticoagulation with warfarin after mechanical heart-valve replacement and the measures to improve the situation. Now the adherence situation of the patients is not satisfying to some extent. There are many things we can do to improve the adherence of patients and get a better anticoagulant effect, such as enhancing the health education according to the different background of patients, strengthening the social and psychological support, carrying out effective follow-up and information communication with the patients, the use of the medicine branch box, importing the foreign managing model of self-test and self-manage, expanding the special outpatient service for anticoagulation instruction. We may get a better adherence of anticoagulation with warfarin and improve the prognosis of patients.

Research progress on strategies to improve patients′ adherence to anticoagulation with warfarin after mechanical heart- valve replacement / 中国实用护理杂志

It is reviewed in this article that the current situation of patients′ adherence to anticoagulation with warfarin after mechanical heart-valve replacement and the measures to improve the situation. Now the adherence situation of the patients is not satisfying to some extent. There are many things we can do to improve the adherence of patients and get a better anticoagulant effect, such as enhancing the health education according to the different background of patients, strengthening the social and psychological support, carrying out effective follow-up and information communication with the patients, the use of the medicine branch box, importing the foreign managing model of self-test and self-manage, expanding the special outpatient service for anticoagulation instruction. We may get a better adherence of anticoagulation with warfarin and improve the prognosis of patients.

Progress of anticoagulant therapy of the patients with mechanical prosthetic valve replacement / 中国胸心血管外科临床杂志

@#The patients with mechanical prosthetic valve replacement need anticoagulant therapy for all their life. The incidence of thromboembolism and anticoagulation-related bleeding events still account for major postoperative complications after mechanical heart valve replacement. Most of the complications happen in the first half year after operation. Therefore, early anticoagulation therapy is very important. Of course, so far most guidelines focus stating their opinions on long-term anticoagulant therapy. However, there is no consensus about anticoagulant therapy in the early period of postoperation. In this review, we summarize early anticoagulant therapy of the patients with mechanical heart valve replacement through consulting domestic and abroad relevant research in recent years and give an overview of the present situations of early anticoagulant therapy.

Transvalvular mitral regurgitation following mitral valve replacement a diagnostic dilemma.

After mitral valve replacement with a prosthetic valve, the valve should be competent and there should not be any residual prosthetic valve regurgitation. Transvalvular residual prosthetic valve regurgitation are difficult to diagnose and quantify. we are reporting interesting TEE images as a diagnostic dilemma in a case of transvalvular mitral regurgitation following mitral valve replacement secondary to entrapment of sub-valvular apparatus in a Chitra mechanical heart valve.

Control perioperatorio de la anticoagulación con antagonistas de la vitamina K en cirugía electiva

Los pacientes anticoagulados crónicamente que son sometidos a cirugías electivas requieren la suspensión temporaria de los antagonistas de vitamina K. El objetivo del presente trabajo fue evaluar la incidencia de eventos tromboembólicos y hemorrágicos en pacientes anticoagulados sometidos a un procedimiento invasivo, aplicando un protocolo de manejo de anticoagulación en el perioperatorio. Se realizó un estudio descriptivo, con datos obtenidos de manera prospectiva, donde se incluyeron mayores de 18 años que ingresaron para la realización de una cirugía electiva. Recibieron sustitución con enoxaparina aquellos con fibrilación auricular(FA) de moderado y alto riesgo de evento tromboembólico, pacientes con reemplazo con válvula cardíaca mecánica(VCM) de moderado y alto riesgo de evento tromboembólico y con tromboembolismo venoso(TEV) de alto riesgo de evento tromboembólico. Se evaluaron los eventos embólicos y hemorrágicos en el perioperatorio. Setenta y ocho recibieron sustitución con enoxaparina en el perioperatorio, edad promedio de 69.4 ± 11.9 años. Veintiocho tenían FA (36.4%), 12 TEV (15.6%) y 37 VCM (48.1%). En el postoperatorio hubo un evento embólico (1.6%) y 12 eventos hemorrágicos (15.4%) de los cuales 10 fueron menores (12.8%) y 2mayores (2.6%). La seguridad de la sustitución con enoxaparina aún es cuestionable, y se deberán esperar estudios aleatorizados, comparando diferentes estrategias de sustitución con heparinas versus la suspensión del tratamiento anticoagulante en el período perioperatorio para una conclusión definitiva.

Anti-coagulated patients who undergo elective surgery require temporary interruption of vitamin K antagonists. The aim of this study was to evaluate the incidence of thromboembolic events and bleeding complications in anti-coagulated patients undergoing elective invasive procedures by using an institutional management protocol. This was a descriptive study with prospective follow-up that included patients over 18 year old anti-coagulated with vitamin K antagonists, undergoing elective surgery. Those with atrial fibrillation (AF) at moderate and high risk of thromboembolic events, with mechanical heart valve (MCV) at moderate and high risk of thromboembolic events, and patients' venous thromboembolism (VTE) at high risk of thromboembolic events received bridging therapy with enoxaparin. Embolic and bleeding events in the pre-operative period were recorded. Seventy- eight received bridging, mean age 69.4 ± 11.9 years. Twenty-eight had AF (36.4 %), 12 had VTE (15.6 %) and 37 had MCV (48.1 %). Postoperatively, 1 embolic event (1.6 %) and 12 bleeding events (15.4 %) were documented, of which 10 were minor (12.8 %) and 2 major (2.6 %). The safety of bridging therapy is still under debate, and we should await the result of randomized studies comparing different strategies of bridging vs. interruption of anticoagulant therapy in the pre-operative period prior to reaching a definitive conclusion.

Safety and Cost-Effectiveness of Bridge Therapies for Invasive Dental Procedures in Patients with Mechanical Heart Valves

PURPOSE: Bridge anticoagulation therapy is mostly utilized in patients with mechanical heart valves (MHV) receiving warfarin therapy during invasive dental procedures because of the risk of excessive bleeding related to highly vascular supporting dental structures. Bridge therapy using low molecular weight heparin may be an attractive option for invasive dental procedures; however, its safety and cost-effectiveness compared with unfractionated heparin (UFH) is uncertain. MATERIALS AND METHODS: This study investigated the safety and cost-effectiveness of enoxaparin in comparison to UFH for bridge therapy in 165 consecutive patients (57+/-11 years, 35% men) with MHV who underwent invasive dental procedures. RESULTS: This study included 75 patients treated with UFH-based bridge therapy (45%) and 90 patients treated with enoxaparin-based bridge therapy (55%). The bleeding risk of dental procedures and the incidence of clinical adverse outcomes were not significantly different between the UFH group and the enoxaparin group. However, total medical costs were significantly lower in the enoxaparin group than in the UFH group (p or =65 years) was significantly associated with an increased risk of total bleeding independent of bridging methods (odds ratio, 2.51; 95% confidence interval, 1.15-5.48; p=0.022). Enoxaparin-based bridge therapy (beta=-0.694, p<0.001) and major bleeding (beta=0.296, p=0.045) were significantly associated with the medical costs within 30 days after dental procedures. CONCLUSION: Considering the benefit of enoxaparin in cost-effectiveness, enoxaparin may be more efficient than UFH for bridge therapy in patients with MHV who required invasive dental procedures.

Associations of POR polymorphisms and warfarin stable maintenance dose in Han Chinese patients / 中国药理学通报

Aim To explore the effect of genetic poly-morphisms of POR on the stable warfarin maintenance doses in Han Chinese patients receiving mechanical heart valve replacement. Methods The association between POR gene polymorphisms and warfarin doses of 185 Han Chinese patients were investigated through ANOVA or t test. SNPs of POR and VKORC1 were de-tected by Sequenom? DNA MassArray genotyping method. CYP2C9*3 was genotyped by polymerase chain reaction-restriction fragment length polymorphism method ( PCR-RFLP ) . Patients ’ clinical characteris-tics, INR value and daily dose were obtained from their medical records. Statistical analysis was performed by SPSS 21. 0 software. Results No mutant carriers of POR rs17148944 , POR rs56256515 and rs72553971 were found in this study. The genotype frequencies of other SNPs were in accordance with Hardy-Weinberg e-quilibrium. In the group of patients with CYP2C9*1*1 , the mutant type carriers ( T carriers ) of POR rs17685 had a significantly higher dose than CC carri-ers(3. 50 ± 1. 07) mg·d-1 vs (3. 14 ± 0. 94) mg· d-1,P =0. 03. Also, in the group of patients with CYP2 C9*1*1 and VKORC1 rs9934438 G allele carri-ers, the mutant type carriers ( T carriers ) of POR rs17685 had a significantly higher dose than CC carri-ers(4. 76 ± 0. 90) mg·d-1 vs (4. 08 ± 1. 03) mg· d-1 ,P=0. 04. No significant difference was found in different genotypes of POR rs2868177 . Conclusion These results illustrate that POR rs17685 T carrier is closely associated with a higher warfarin maintenance dose, suggesting that this SNP is useful for clinical guidance of warfarin.

Pregnancy Outcomes Compared in Women with Mechanical Heart Valve Replacements Anticoagulated with Warfarin and Enoxaparin in Pregnancy

The anticoagulation of choice for mechanical heart valves is the oral anticoagulant warfarin. Warfarin is associated with increased risk of miscarriage, intrauterine fetal deaths and warfarin embryopathy. This longitudical cross-over study of 5 women observed all 5 having livebirths of healthy infants after heparin-managed pregnancies. Their earlier 8 pregnancies had all resulted in perinatal losses or miscarriages when on regimes based on warfarin.

Relationship between the Occurrence of Thromboembolism and INR Measurement Interval in Low Intensity Anticoagulation after Aortic Mechanical Valve Replacement

BACKGROUND: We investigated changes in the International Normalized Ratio (INR) and its measurement interval in patients with thromboembolic events who were treated by low intensity anticoagulation therapy after isolated mechanical aortic valve replacement. MATERIALS AND METHODS: Seventy-seven patients who underwent surgery from June 1990 to September 2006 were enrolled in the study and observed until August 2008. The patients were followed up at 4~8 week intervals and their warfarin (Coumadin)(R) dosage was adjusted aiming for a target range of INR 1.5~2.5. The rate of thromboembolic events was obtained. Changes in the mean INR and INR measurement interval were comparatively analyzed between the normal group (event free group, N=52) who had no anticoagulation-related complications and the thromboembolic group (N=10). Hospital records were reviewed retrospectively. RESULTS: The observation period was 666.75 patient-years. Thromboembolic events occurred in 10 patients. The linearized occurrence rate of thromboembolism was 1.50%/patient-years. Actuarial thromboembolism-free rates were 97.10+/-2.02% at 5 years, 84.30+/-5.22% at 10 years, and 67.44+/-12.14% at 15 years. The percentages of INR within the target range and mean INR were not statistically significantly different for the normal and thromboembolic groups. However, the mean INR during the segmented period just before the events showed a significantly lower level in the thromboembolic group (during a 4 month period: normal group, 1.86+/-0.14 vs. thromboembolic group, 1.50+/-0.28, p<0.001). The mean intervals of INR measurement during the whole observation period showed no significant differences between groups, but in the segmented period just before the events, the interval was significantly longer in thromboembolic group (during a 6 month period: normal group, 49.04+/-9.47 days vs. thromboembolic group, 65.89+/-44.88 days, p<0.01). CONCLUSION: To prevent the occurrence of thromboembolic events in patients who receive isolated aortic valve replacement and low intensity anticoagulation therapy, we suggest that it would be safe to maintain an INR level above 1.8 and to measure the INR at least every 7~8 weeks.

Low-intensity Oral Anticoagulation Versus High-intensity Oral Anticoagulation in Patients with Mechanical Bileaflet Prosthetic Heart Valves / 대한흉부외과학회지

BACKGROUND: All the patients with mechanical valves require warfarin therapy in order to prevent them from developing thromboembolic complications. According to the ACC/AHA practice guidelines, after AVR with bileaflet mechanical prostheses in patients with no risk factors, warfarin is indicated to achieve an INR of 2.0 to 3.0. After MVR with any mechanical valve, warfarin is indicated to achieve an INR of 2.5 to 3.5. But in our clinical experience, bleeding complications (epistaxis, hematuria, uterine bleeding, intracerebral hemorrhage etc.) frequently developed in patients who maintained their INR within this value. So, we retrospectively reviewed the patients with bileaflet mechanical heart valve prosthesis and we determined the optimal anticoagulation value. MATERIAL AND METHOD: From January 1984 to February 2007, 311 patients have been followed up at a national medical center. We classified the AVR patients (n=60) into three groups as follows: an INR from 1.5 to 2.0 in Group I, an INR from 2.0 to 2.5 in Group II and an INR from 2.5 to 3.0 in Group III. We classified the MVR (n=171) and DVR (n=80) patients into four groups as follows: an INR from 1.5 to 2.0 in Group I, an INR from 2.0 to 2.5 in Group II, an INR from 2.5 to 3.0 in Group III and an INR from 3.0 to 3.5 in Group III. We compared the groups for their thromboembolic and bleeding complications by means of the Kaplan Meier method. RESULT: In the AVR patients, 2 thromboembolic complications and 4 bleeding complications occurred and the log rank test failed to identify any statistical significance between the groups for thethromboembolic complication rate, but groups I and II had lower bleeding complication rates than did group III. Thirteen thromboembolic complication and 15 bleeding complication occurred in the MVR and DVR patients, and the log rank test also failed to identify statistical significance between the groups for the thromboembolic complication rate, but groups I and II had lower bleeding complication rates that did groups III and IV. CONCLUSION: The thromboembolic complication rate was not statistically different between groups I and II and groups III and IV, but the bleeding complication rates of groups I and II were lower than those of groups III and IV. So this outcome encouraged us to continue using our low intensive anticoagulation regime, that is, an INR of 1.5 to 2.5.

Importance and the Related Issues of Pharmaceutical Care for Application of Warfarin in Patients with Mechanical Valve Replacement / 中国药房

OBJECTIVE:To reduce the incidence of complications in anticoagulant treatment for patients with mechanical heart valve replacement.METHODS:The factors affecting the anticoagulative efficacy of warfarin were analyzed,and pharmaceutical care was performed for patients to provide them with guidance about the standard use of warfarin in case of the problems likely occurred during the anticoagulant treatment.RESULTS & CONCLUSION:The anticoagulative efficacy of warfarin was influenced by many factors.It is important for pharmacists to carry out active,reasonable and effective pharmaceutical care so as to reduce the incidences of bleeding and thrombus during anticoagulant treatment,avoid drug-induced physical lesions and improve patients' quality of life after surgery.

Clinical Pharmacists' Experience about the Practice of Anticoagulation Management of the Patients Who Had Been Discharged from Hospital after Undergoing Mechanical Heart Valve Replacement / 中国药房

OBJECTIVE:To explore the function and approach of clinical pharmacists' participating in the anticoagulation management of patients who had been discharged from hospital after undergoing mechanical heart valve replacement.METHODS:The experiences of clinical pharmacists obtained through first-hand practice in the anticoagulation management and pharmaceutical care of the patients who had been discharged from hospital after undergoing mechanical heart valve replacement were introduced by illustrating examples.RESULTS & CONCLUSION:Clinical pharmacists' participating in the anticoagulation management of patients who had been discharged from hospital after undergoing mechanical heart valve replacement provide physicians and patients with pharmaceutical information and pharmaceutical care and enhance the effectiveness and safety of anticoagulative therapy accordingly.

Perioperative Anticoagulation in Patients with Mechanical Heart Valves Undergoing Elective Surgery: Results of a Survey Conducted among Korean Physicians

The optimal perioperative anticoagulation management in patients on warfarin therapy is poorly defined due to the lack of randomized trials. Because guidelines are heterogeneous, it was hypothesized that "treatment strategies are not uniform in clinical practice". Between February 2003 and May 2003, a questionnaire with 4 different clinical scenarios was distributed to physicians by e-mail, or direct contact was made by a survey monitor. Two scenarios described the cases of patients with a mechanical heart valve (MHV) in the mitral position, with additional risk factors for a systemic embolism; one undergoing major (scenario 1) and the other minor surgery (scenario 3). Two scenarios described patients with an aortic MHV; one undergoing major (scenario 2) and the other minor (scenario 4) surgery. Different preoperative and postoperative management options were offered. The treatment options for all scenarios were the same. Of the 90 questionnaires distributed, 52 (57.8%) were returned. Hospitalization for full-dose intravenous unfractionated heparin (IV UH) was the most commonly selected strategy in the preoperative phase for scenarios 1 (59%), 2 (42%) and 3 (44%). In scenario 4, 34% chose IV UH. Outpatient, full- dose, subcutaneous UH or low-molecular-weight heparin (LMWH) was the most selected option in the postoperative phase for all scenarios, with the exception of number 4 (52.9% in scenario 1, 34% in scenario 2, 32%, in scenario 3 and 28% in scenario 4). Even among expert clinicians, the management of perioperative anticoagulation is heterogeneous. In particular, the definition of risk categories and the optimal intensity of antithrombotic drugs need to be defined by well-designed prospective studies.