American Heart Association/American College of Cardiology Foundation guide to warfarin therapy

Anticoagulation control among patients on vitamin K antagonists in nine countries in Sub-Saharan Africa

Vitamin K antagonists (VKA) is the primary anticoagulant in most settings of Sub-Saharan Africa. Understanding the quality of anticoagulation services in the continent is vital in optimising the intended benefits. This study assessed the quality of anticoagulation and associated factors among VKA-treated patients in nine SSA countries. We conducted a retrospective cohort study of randomly selected patients on anticoagulation from 20 clinics in Botswana, the Democratic Republic of Congo, Ethiopia, Gambia, Ghana, Mozambique, Nigeria, Tanzania, and South Africa. Eligible participants were those on VKAs for at least three months and with at least four international normalised ratios (INR) results in 2019-2021. We report the proportion of INR values in the therapeutic range, time-in-therapeutic range (TTR) using the Rosendaal method, and the proportion of patients with TTR ≥ 65% (optimal anticoagulation). The mean age was 51.1(16.1) years, and 64.2% were women. The most common indications for VKA included venous thromboembolism (29.6%), prosthetic valves (26.7%) and atrial fibrillation/flutter (30.1%). We analysed 6743 INR tests from 1011 participants, and of these, 48.5% were sub-therapeutic, 34.1% therapeutic, and 17.4% were supratherapeutic relative to disease-specific reference ranges. TTR was calculated for 660 patients using 4927 INR measurements. The median (interquartile range [IQR]) TTR was 35.8(15.9,57.2) %. Optimal anticoagulation control was evident in 19.2% of participants, varying from 2.7% in Tanzania to 23.1% in Ethiopia. The proportion of patients with TTR ≥ 65% was 15,4% for prosthetic heart valves, 21.1% for venous thromboembolism and 23.7% for atrial fibrillation or flutter. Countries with universal health coverage had higher odds of optimal anticoagulation control (adjusted odds ratio (aOR) 1.79, 95% confidence interval [CI], 1.15- 2.81, p = 0.01). Patients on VKAs for different therapeutic indications in SSA had suboptimal TTR. Universal health coverage increased the odds of achieving TTR by 79%. The evidence calls for more intensive warfarin management strategies in SSA, including providing VKA services without out-of-pocket payments.

SAMe-TT2R2 Score to Predict Time in Therapeutic Range of Vitamin K Antagonists in Asian and Non-Asian patients: A Systematic Review and Meta-analysis

BACKGROUND

Sex, age, medical history, treatment, tobacco use, and race (SAMe-TT2R2) score helps detect patients at risk of suboptimal anticoagulation control. A score above two suggests poor control; however, non-Caucasian status being assigned two points might hinder the recognition of poor control in patients of other races.

OBJECTIVE

To evaluate the SAMe-TT2R2 score's ability to predict poor anticoagulation control [defined as time in therapeutic range (TTR) < 60-70%] in Asian and non-Asian populations on vitamin K antagonists (VKAs).

METHODS

We searched PubMed, Cochrane Library, Scopus, SpringerLink, and Web of Science using the keyword "SAMe-TT2R2." Articles published before April 2022 were screened. We gathered mean TTR and diagnostic accuracy data for different SAMe-TT2R2 thresholds and conducted meta-analyses using random-effects models.

RESULTS

A total of 30 studies were included (N = 36,690). The overall mean TTR differences were - 4.88 and - 6.41 for the cutoffs of ≥ 3 and ≥ 4, respectively. For non-Asian patients, the mean TTR differences were - 3.86, - 5.12, and - 8.09 for the cutoffs ≥ 2, ≥ 3, and ≥ 4, respectively. For Asian patients, the mean TTR differences were - 3.99 and - 4.07 for the cut-offs ≥ 3 and ≥ 4, respectively. The highest positive likelihood ratio (LR+) for the Asian subgroup was 1.17 [95% confidence interval (CI): 1.06-1.28; I2 = 0%, p heterogeneity = 0.500] at cutoff ≥ 4 and for the non-Asian subgroup, at cut-off ≥ 3, the LR+ was 1.24 (95% CI 1.14-1.34; I2 = 0% p heterogeneity = 0.455). The lowest LR- was found at a lower cutoff for both races (at cutoff ≥ 3 and ≥ 2 for Asian and non-Asian subgroups, respectively). The pooled results of other accuracy parameters were modest at all cutoffs, except for the sensitivity at cutoff ≥ 3 in the Asian subgroup (83.05%).

CONCLUSION

Our study results suggest that a higher SAMe-TT2R2 score resulted in a greater reduction of TTR among Asian and all races. The accuracy parameters showed the highest sensitivity for poor TTR at the SAMe-TT2R2 cutoff of ≥ 3 for Asian patients. However, the ability to identify patients likely to have poor TTR was limited. Further research is needed to enhance the risk assessment for poor anticoagulation control with VKAs.

REGISTRATION

The protocol of this systematic review was registered in the International Prospective Register of Scientific Reviews: PROSPERO, registration number CRD42021291865.

Unlocking the Molecular Behavior of Natural Amine-Targeted Carbon Quantum Dots for the Synthesis of Diverse Pharmacophore Scaffolds via an Unusual Nanoaminocatalytic Route

Despite the fact that carbon quantum dots (CQDs) have significant catalytic potential, only emblematic applications that rely on simple acid-base or hydrogen-bonding activation pathways have been reported. In this study, natural amine-targeted CQDs (NAT-CQDs) have been successfully fabricated using a sustainable technique that harnesses a renewable green source. Based on a holistic sustainable assessment, the present approach for the synthesis of NAT-CQDs surpasses previously reported methods in terms of estimated circular and good-manufacturing-practice metrics. A set of spectroscopic and analytical techniques, including FTIR, XPS, conductometric assay, pH titration, 19FNMR, and 13CNMR confirms the presence of the assessable amino-rich groups (0.0083N) at the surface of NAT-CQDs. The occurrence of surface amine groups unlocked the molecular behavior of as-prepared NAT-CQDs and makes them an unprecedented nanoaminocatalytic platform for the synthesis of diverse pharmacophore scaffolds (>40 examples) via a one-pot Knoevenagel/(aza) Michael addition reaction in water at room temperature. The assessable amine group can covalently activate carbonyl groups through nucleophilic iminium activation modes in water and facilitate the ability to build valuable and therapeutic scaffolds on a gram scale. By transferring significant molecular primacy at the frontier of nanoscale materials, NAT-CQDs can thus bridge the gap between the nanoscale and molecular domains. This protocol can also be applied for the preparation of therapeutic anticoagulant drugs, warfarin, and coumachlor. All the reactions exhibited a high atom economy, low E-factor, low process mass intensity (PMI), high reaction mass efficiency (RME), high carbon efficiency (CE), and high catalyst reusability with overall high sustainable values. NAT-CQDs show high recyclability, and the spectral data of reused catalysts indicate that the NAT-CQDs maintained their surface chemistry and electronic properties, suggesting their stability under the tested conditions. This study presents a remarkable instance of NAT-CQDs showcasing covalent catalysis. Expanding on the aforementioned design concept, the utilization of NAT-CQDs' "potential" as distinct colloidal organocatalysts in aqueous environments at the molecular level introduces valuable prospects for aminocatalytic pathways.

Assessing the knowledge of medical undergraduates on oral anticoagulation therapy

Objective

Oral anticoagulant drugs, such as warfarin, are widely used for preventing and treating vascular and thromboembolic disease in patients with chronic atrial fibrillation, venous thrombosis, and coronary heart disease. As oral anticoagulant therapy has such a narrow therapeutic range, complications in administering these drugs can prove to have a detrimental effect on patients such as life-threatening bleeding might occur. It is therefore necessary to have an adequate knowledge about its actions and its interactions with other dietary factors or any other medication involved. This study was therefore formulated in order to evaluate the knowledge as well as to impart proper awareness to the medical undergraduate students about oral anticoagulation therapy such as to prevent any untoward situation that may arise from the process.

Methods

A cross-sectional descriptive study was used to assess the knowledge on oral anticoagulant therapy among the medical undergraduates of a tertiary care hospital. A pre-validated structured questionnaire consisting of 28 questions was adopted, and a separate questionnaire was used for each student. Timing of answering the questionnaire was set at 30 minutes. Scores were evaluated such as a correct answer was given a score of one and wrong answer awarded as zero. Adequate knowledge sore was set above 70% and inadequate knowledge at less than 40%.

Results

The response rate was found out to be 67.33% with gender distribution observed to be 71% females and 29% males. From the answers evaluated, overall average score of 67.3 ± 15.9 was obtained indicating that most of the respondents have adequate knowledge about the different mechanism, drug-drug interactions, drug-food interactions, and side effects of anticoagulant therapy, and 100% of the students are well aware about the complications and procedures involved to dissipate information about warfarin therapy.

Conclusions

Adequate exposure of students to clinical cases will further help them to focus on the importance of anticoagulation and strengthening their knowledge regarding anticoagulant drug therapy. This will influence the process of physician-patient communication for improving anticoagulation outcome.

Venous Thromboembolism Prophylaxis in Major Orthopedic Surgeries and Factor XIa Inhibitors

Venous thromboembolism (VTE), comprising pulmonary embolism (PE) and deep vein thrombosis (DVT), poses a significant risk during and after hospitalization, particularly for surgical patients. Among various patient groups, those undergoing major orthopedic surgeries are considered to have a higher susceptibility to PE and DVT. Major lower-extremity orthopedic procedures carry a higher risk of symptomatic VTE compared to most other surgeries, with an estimated incidence of ~4%. The greatest risk period occurs within the first 7-14 days following surgery. Major bleeding is also more prevalent in these surgeries compared to others, with rates estimated between 2% and 4%. For patients undergoing major lower-extremity orthopedic surgery who have a low bleeding risk, it is recommended to use pharmacological thromboprophylaxis with or without mechanical devices. The choice of the initial agent depends on the specific surgery and patient comorbidities. First-line options include low-molecular-weight heparins (LMWHs), direct oral anticoagulants, and aspirin. Second-line options consist of unfractionated heparin (UFH), fondaparinux, and warfarin. For most patients undergoing knee or hip arthroplasty, the initial agents recommended for the early perioperative period are LMWHs (enoxaparin or dalteparin) or direct oral anticoagulants (rivaroxaban or apixaban). In the case of hip fracture surgery, LMWH is recommended as the preferred agent for the entire duration of prophylaxis. However, emerging factor XI(a) inhibitors, as revealed by a recent meta-analysis, have shown a substantial decrease in the occurrence of VTE and bleeding events among patients undergoing major orthopedic surgery. This discovery poses a challenge to the existing paradigm of anticoagulant therapy in this specific patient population and indicates that factor XI(a) inhibitors hold great promise as a potential strategy to be taken into serious consideration.

A regional anticoagulation program improves safety and outcomes for both children and adults

BACKGROUND

Evidence-based anticoagulation programs usually serve a local, adult patient population. Here we report outcomes for a regional combined pediatric-adult program.

AIMS

The aims of this study were: (1) Compare the pre- vs. post-implementation quality of therapy (% time in therapeutic range (%TTR) and compliance). (2) Assess anticoagulant-relevant outcomes (bleeding and thrombotic complications).

METHODS

Data were collected for the years 2014-2019. Rosendaal linear interpolation was used to calculate %TTR. Bleeding complications were categorized using ISTH-SSC standard nomenclature and new thrombotic events were reviewed.

RESULTS

The patients were divided into a long-term warfarin group (N = 308), 80.2% of whom had cardiac-related therapeutic indications (median age 24y), and a second group (N = 114) comprised of short-term and non-warfarin long-term anticoagulation (median age 16y). Median %TTR for those on long-term warfarin was 78.9%. The incidence of major and clinically relevant non-major bleeding events was 1.65 and 2.43 /100 person-years of warfarin use, respectively. Thromboembolism (TE) incidence was 0.78/100 patient-years of warfarin use. Neither bleeding nor thrombosis was associated with %TTR (p = 0.48). Anticoagulant indication was the only variable associated with bleeding risk (p = 0.005). The second group had no on-therapy TE events but 7.9% experienced bleeding. Complete data were available for a randomly sampled pre-program warfarin group (N = 26). Median %TTR improved from 17.5 to 87% pre- vs. post-implementation. Similarly, compliance (defined as ≥ 1 INR/month) improved by 34.3%.

CONCLUSIONS

In conclusion, this program significantly improved and sustained %TTR and compliance. The lack of association between bleeding and thrombosis events and %TTR may be related to the high median %TTR (> 70%) achieved by this approach.

Contemporary Antiplatelet and Anticoagulant Therapies for Secondary Stroke Prevention: A Narrative Review of Current Literature and Guidelines

PURPOSE OF REVIEW

Stroke is a leading cause of death and disability worldwide. The annual incidence of new or recurrent stroke is approximately 795,000 cases per year in the United States, of which 87% are ischemic in nature. In addition to the management of modifiable high-risk factors to reduce the risk of recurrent stroke, antithrombotic agents (antiplatelets and anticoagulants) play an important role in secondary stroke prevention. This review will discuss the published literature on the use of antiplatelets and anticoagulants in secondary prevention of acute ischemic stroke and transient ischemic attack (TIA), including their pharmacology, efficacy, and adverse effects. We will also highlight the role of dual antiplatelet therapy (DAPT) in secondary stroke prevention, along with supporting literature.

RECENT FINDINGS

Single antiplatelet therapy (SAPT) with aspirin or clopidogrel reduces the risk of recurrent ischemic stroke in patients with non-cardioembolic ischemic stroke or TIA. However, as shown in recent trials, short-term DAPT with aspirin and clopidogrel or ticagrelor for 21-30 days is more effective than SAPT in patients with minor acute non-cardioembolic stroke or high-risk TIA. Although short-term DAPT is highly effective in preventing recurrent stroke, a more prolonged course can increase bleeding risks without additional benefit. DAPT for 90 days, followed by aspirin monotherapy for patients with large vessel intracranial atherosclerotic disease, is suitable for secondary stroke prevention. However, patients need to be monitored for both minor (e.g., bruising) and major (e.g., intracranial) bleeding complications. Conversely, oral warfarin and newer direct oral anticoagulant (DOACs) such as dabigatran, rivaroxaban, apixaban, and edoxaban are the agents of choice for secondary stroke prevention in patients with non-valvular cardioembolic strokes. DOACs may be preferred over warfarin due to decreased bleeding risks, including ICH, lack of need for international normalized ratio monitoring, no dietary restrictions, and limited drug-drug interactions. The choice between different antiplatelets and anticoagulants for prevention of ischemic stroke depends on the underlying stroke mechanism, cytochrome P450 2C19 polymorphisms, bleeding risk profile, compliance, drug tolerance, and drug resistance. Physicians must carefully weigh each patient's relative benefits and bleeding risks before initiating an antiplatelet/anticoagulant treatment regimen. Further studies are warranted to study the optimal duration of DAPT in symptomatic intracranial atherosclerosis since the benefit is most pronounced in the short term while the bleeding risk remains high during the extended duration of therapy.

Perioperative Management of Oral Antithrombotics in Dentistry and Oral Surgery: Part 2

Part 1 of "Perioperative Management of Oral Antithrombotics in Dentistry and Oral Surgery" covered the physiological process of hemostasis and the pharmacology of both traditional and novel oral antiplatelets and anticoagulants. Part 2 of this review discusses various factors that are considered when developing a perioperative management plan for patients on oral antithrombotic therapy in consultation with dental professionals and managing physicians. Additionally included are how thrombotic and thromboembolic risks are assessed as well as how patient- and procedure-specific bleeding risks are evaluated. Special attention is given to the bleeding risks associated with procedures encountered when providing sedation and general anesthesia within the office-based dental environment.

Optimizing warfarin dosing using deep reinforcement learning

Warfarin is a widely used anticoagulant, and has a narrow therapeutic range. Dosing of warfarin should be individualized, since slight overdosing or underdosing can have catastrophic or even fatal consequences. Despite much research on warfarin dosing, current dosing protocols do not live up to expectations, especially for patients sensitive to warfarin. We propose a deep reinforcement learning-based dosing model for warfarin. To overcome the issue of relatively small sample sizes in dosing trials, we use a Pharmacokinetic/ Pharmacodynamic (PK/PD) model of warfarin to simulate dose-responses of virtual patients. Applying the proposed algorithm on virtual test patients shows that this model outperforms a set of clinically accepted dosing protocols by a wide margin. We tested the robustness of our dosing protocol on a second PK/PD model and showed that its performance is comparable to the set of baseline protocols.

Opposite Response to Vitamin K Antagonists: A Report of Two Cases and Systematic Review of Literature

Vitamin K antagonists (VKAs) are used in the prophylaxis and treatment of thromboembolic disorders. Despite a high efficacy, their narrow therapeutic window and high response variability hamper their management. Several patients experience fluctuations in dose−response and are at increased risk of over- or under-anticoagulation. Therefore, it is essential to monitor the prothrombin time/international normalized ratio to determine the so-called stable dose and to adjust the dosage accordingly. Three polymorphisms, CYP2C9∗2, CYP2C9∗3 and VKORC1-1639G>A, are associated with increased sensitivity to VKAs. Other polymorphisms are associated with a request for a higher dose and VKA resistance. We described the clinical cases of two patients who were referred to the Clinical Pharmacology and Pharmacogenetics Unit of the University Hospital of Salerno for pharmacological counseling. One of them showed hypersensitivity and the other one was resistant to VKAs. A systematic review was performed to identify randomized clinical trials investigating the impact of pharmacogenetic testing on increased sensitivity and resistance to VKAs. Although international guidelines are available and information on the genotype-guided dosing approach has been included in VKA drug labels, VKA pharmacogenetic testing is not commonly required. The clinical cases and the results of the systematically reviewed RCTs demonstrate that the pharmacogenetic-based VKA dosing model represents a valuable resource for reducing VKA-associated adverse events.

Direct oral anticoagulants in patients with chronic thromboembolic pulmonary hypertension and the presence of recent thrombus during pulmonary endarterectomy

Patients with chronic thromboembolic pulmonary hypertension (CTEPH) require lifelong anticoagulant therapy. The safety and efficacy of direct oral anticoagulant (DOAC) in the chronic and transitional management of CTEPH has not been investigated. We performed a retrospective analysis of 405 consecutive pulmonary endarterectomy (PEA) cases at the University of California, San Diego, from July 2015 through July 2017. PEA specimen was reviewed for the presence of acute or subacute thrombotic material distinct from the expected chronic disease removed at the time of PEA by two investigators blinded to the patient information. Of 405 PEA cases, 166 patients (41.0%) were anticoagulated with one of three available DOACs; 239 (59.0%) presented on either oral vitamin‐K antagonist or chronic injectable therapy. There were no significant differences in baseline characteristics between DOAC and non‐DOAC groups. Evidence of recent thrombus was observed in 22 (13.3%) in the DOAC group versus 16 (6.7%) within the non‐DOAC group. The odds ratio of DOACs usage and evidence of recent thrombus was 2.34 (95% confidence interval: 1.1–5.0, p = 0.03) after adjusting for age, gender, race, body mass index, and history of antiphospholipid antibody syndrome. CTEPH patients referred for PEA while on DOAC therapy were twice as likely to have associated acute or subacute thrombi present at the time of surgery compared with those on more traditional, non‐DOAC anticoagulant therapies. This raises questions of the safety and efficacy of DOACs in the chronic management of CTEPH.

Impact of the COVID-19 pandemic on England's national prescriptions of oral vitamin K antagonist (VKA) and direct-acting oral anticoagulants (DOACs): an interrupted time series analysis (January 2019-February 2021)

BACKGROUND

Direct-acting oral anticoagulants (DOACs) were developed as an alternative to warfarin to treat and prevent thromboembolism, including stroke prevention in non-valvular atrial fibrillation patients. The COVID-19 pandemic could increase the risk of stroke and/or the risk of bleeding in patients due to nonadherence or sub/supra-optimal dosing.

OBJECTIVE

To investigate DOAC prescription trends in England's community settings during the complete first wave of COVID-19 pandemic.

METHODS

Descriptive and interrupted time series (ITS) analyses were conducted to examine the prescription patterns of DOACs (dabigatran, rivaroxaban, apixaban and edoxaban) and warfarin for primary care patients in the English Prescribing Dataset from January 2019 to February 2021, with March 2020 as the cut-off point.

RESULTS

A 19% increase in mean DOAC's accompanied with 20% warfarin prescriptions decline was observed. ITS modelling showed an increase in DOAC prescription volume in March 2020 (+7 million items, p = 0.008). The pre-existing upward trend in DOAC prescriptions slowed during the period (-427,000 items, p = 0.007). Apixaban was the most frequently used DOAC and had the largest step-change in March 2020 (+5 million items, p = 0.010). The mean monthly combined cost of DOACs and warfarin was higher during the period. DOAC prescription trends were consistent across England's regions. Conclusion: The overall oral anticoagulants use in this period was lower than expected, indicating a medical needs gap, possibly due to adherence issues. The potential clinical and logistical consequences warrant further study to identify contributing factors and mitigate avoidable risks.

Vitamin K-dependent anticoagulant use and level of anticoagulation control in sub-Saharan Africa: protocol for a retrospective cohort study

BACKGROUND

Given that vitamin K-dependent anticoagulants (VKAs) will continue to be the primary anticoagulant in Africa for a long time, understanding the quality of anticoagulation services in the continent is vital for optimising the intended benefits. Notably, a few small studies have assessed the quality of anticoagulation in sub-Saharan Africa (SSA) countries. This study will describe the current VKA use and anticoagulation control among patients in selected SSA countries.

METHODS AND ANALYSIS

We plan to review the 2019 anticoagulation data of a cohort of 800 random patients from 19 selected clinics in Botswana, the Democratic Republic of Congo, Ethiopia, Gambia, Ghana, Mozambique, Nigeria, Tanzania and South Africa. We expect at least one participating site to enrol 100 participants in each country. Eligible participants will be those on VKAs for at least 3 months and with at least four international normalised ratio (INR) results. We will document the indications, type and duration of VKA use, sociodemographic factors, coexisting medical conditions, concurrent use of drugs that interact with warfarin and alcohol and tobacco products. The level of anticoagulation control will be determined by calculating the time-in-therapeutic range (TTR) using the Rosendaal and the Percent of INR in TTR methods. A TTR of less than 65% will define a suboptimal anticoagulation control.

ETHICS AND DISSEMINATION

This study was approved by the Ministry of Health and Wellness Ethics Committee (HPDME13/8/1) in Botswana and local research ethics committees or institutional review boards of all participating sites. As the study collects data from existing records, sites applied for waivers of consent. We will disseminate research findings through peer-reviewed scientific publications.

Pharmacogenomics Informs Cardiovascular Pharmacotherapy

Precision medicine exemplifies the emergence of personalized treatment options which may benefit specific patient populations based upon their genetic makeup. Application of pharmacogenomics requires an understanding of how genetic variations impact pharmacokinetic and pharmacodynamic properties. This particular approach in pharmacotherapy is helpful because it can assist in and improve clinical decisions. Application of pharmacogenomics to cardiovascular pharmacotherapy provides for the ability of the medical provider to gain critical knowledge on a patient's response to various treatment options and risk of side effects.

Genomewide association analysis of warfarin dose requirements in Middle Eastern and North African populations

To date, there has been no genomewide association study (GWAS) from the Middle East and North African (MENA) region to identify genetic variants associated with warfarin dose variability using this approach. In this study, we aimed to conduct the first GWAS of warfarin dose requirements in patients from the MENA region. A total of 132 Qatari (discovery) and 50 Egyptians (replication) were genotyped using Illumina Multi‐Ethnic Global BeadChip Array. A GWAS was performed on log‐transformed weekly warfarin dose in the studied population, adjusting for clinical characteristics and ancestry. The genomewide signals from the discovery cohort were tested in the Egyptian cohort. A GWAS meta‐analysis, including the Qatari and Egyptian cohorts, was also performed and the output from this analysis was used in a gene‐based analysis. The discovery analysis in Qatari identified five genomewide single‐nucleotide polymorphisms (SNPs) in chromosome 16. These signals were replicated in the Egyptian cohort. Combining the two data through a GWAS meta‐analysis strengthened the association in chromosome 16 with VKORC1 rs9934438 being the lead genomewide signal (β = −0.17, 6 × 10⁻¹⁵). Other SNPs were identified in chromosome 10 at a p value less than 1 × 10⁻⁵. The genetic variants within VKORC1 rs9934438 and CYP2C9 rs4086116 explained 39% and 27% of the variability in the weekly warfarin dose requirement in the Qatari and Egyptians, respectively. This is the first GWAS of warfarin dose variability in the MENA region. It confirms the importance of VKORC1 and CYP2C9 variants in warfarin dose variability among patients from the MENA region.

Eighty years of oral anticoagulation: Learning from history

In the year 2021 we celebrate the 80th anniversary of the first clinical use of vitamin K antagonists (VKAs), the mainstay of prevention and long-term treatment of thromboembolic disease. The discovery and development of oral anticoagulants is one of the most important chapters in the history of medicine, a goal pursued by physicians trying to combat the clinical manifestations of thrombosis since ancient times. Until the last decade, VKAs were the only oral anticoagulants available and used in clinical practice. Today, their clinical use has progressively shrunk, as the non-vitamin K antagonist oral anticoagulants (NOACs) are increasingly replacing VKAs in various conditions after the successful completion of several large randomized controlled trials. Currently, new research is tackling upstream components of the intrinsic pathway - particularly factor XI and factor XII - for the development of new, even safer anticoagulants promising to reduce bleeding without compromising efficacy. This review highlights the evolution of oral anticoagulant therapy tracing the key stages of a long and fascinating history that has unfolded from the first part of the twentieth century until today, indeed an intriguing journey where serendipity is intertwined with the tenacious work of many researchers.

Long‐term antithrombotic therapy for patients with atrial fibrillation and stable coronary artery disease

This is a protocol for a Cochrane Review (intervention). The objectives are as follows:

To assess the efficacy and safety of different long‐term antithrombotic regimens for people with AF and stable CAD.

Assessment of the attitude, awareness and practice of periprocedural warfarin management among health care professional in Qatar. A cross sectional survey

It is estimated that 10-15% of oral anticoagulant (OAC) patients, would need to hold their OAC for scheduled surgery. Especially for warfarin, this process is complex and requires multi-layer risk assessment and decisions across different specialties. Clinical guidelines deliver broad recommendations in the area of warfarin management before surgery which can lead to different trends and practices among practitioners. To evaluate the current attitude, awareness, and practice among health care providers (HCPs) on warfarin periprocedural management. A multiple-choice questionnaire was developed, containing questions on demographics and professional information and was completed by187 HCPs involved in warfarin periprocedural management. The awareness median (IQR) score was moderate [64.28% (21.43)]. The level of awareness was associated with the practitioner's specialty and degree of education (P = 0.009, 0.011 respectively). Practice leans to overestimate the need for warfarin discontinuation as well as the need for bridging. Participants expressed interest in using genetic tests to guide periprocedural warfarin management [median (IQR) score (out of 10) = 7 (5)]. In conclusion, the survey presented a wide variation in the clinical practice of warfarin periprocedural management. This study highlights that HCPs in Qatar have moderate awareness. We suggest tailoring an educational campaign or courses towards the identified gaps.

Patient-related factors associated with oral anticoagulation control: a population-based cohort study

OBJECTIVES

Time in therapeutic range (TTR) of ≥70% is a commonly used indicator of optimal anticoagulation control. This study aimed to determine the patterns and predictors of anticoagulation control in a population-based cohort of new users of warfarin.

METHODS

This was a retrospective cohort study. All adults (age ≥18 years) who had been newly initiated on warfarin therapy between January 2006 and March 2011were selected from administrative health databases. TTR was calculated using the Rosendaal method. Multivariable logistic regression models were used to identify patient-related factors associated with optimal TTR. Predictors of patients spending >30% of time above and below the therapeutic international normalised ratio (INR) range were also examined.

KEY FINDINGS

A total of 6032 patients were included in this study. The mean TTR was 54.1 ± 18.8%, and 82.3% of patients had subthreshold TTR (<70%). Compared with New Zealand Europeans, Māori and Pacific people had decreased odds of achieving optimal TTR and increased odds of spending >30% of time below the therapeutic INR range. Patients aged 65-74 years and 75 years or older had increased odds of achieving optimal TTR but decreased odds of spending >30% of time below the therapeutic INR range than those <65 years. Compared with those living in the least socioeconomically deprived areas, those living in the most deprived areas had decreased odds of achieving optimal TTR.

CONCLUSIONS

Anticoagulation control with warfarin is suboptimal in routine care in New Zealand. Age, ethnicity and deprivation index were significant predictors of TTR. It is important to ensure equitable access to appropriate, high-quality care for those living in deprived areas and those from ethnic minority groups.

Warfarin maintenance dose prediction for Chinese after heart valve replacement by a feedforward neural network with equal stratified sampling

Patients requiring low-dose warfarin are more likely to suffer bleeding due to overdose. The goal of this work is to improve the feedforward neural network model's precision in predicting the low maintenance dose for Chinese in the aspect of training data construction. We built the model from a resampled dataset created by equal stratified sampling (maintaining the same sample number in three dose-groups with a total of 3639) and performed internal and external validations. Comparing to the model trained from the raw dataset of 19,060 eligible cases, we improved the low-dose group's ideal prediction percentage from 0.7 to 9.6% and maintained the overall performance (76.4% vs. 75.6%) in external validation. We further built neural network models on single-dose subsets to invest whether the subsets samples were sufficient and whether the selected factors were appropriate. The training set sizes were 1340 and 1478 for the low and high dose subsets; the corresponding ideal prediction percentages were 70.2% and 75.1%. The training set size for the intermediate dose varied and was 1553, 6214, and 12,429; the corresponding ideal prediction percentages were 95.6, 95.1%, and 95.3%. Our conclusion is that equal stratified sampling can be a considerable alternative approach in training data construction to build drug dosing models in the clinic.

Bridging vs Non-Bridging with Warfarin Peri-Procedural Management: Cost and Cost-Effectiveness Analyses

The warfarin peri-procedural management in Qatar is predominantly based on bridging (63%), compared to non-bridging. This study sought to perform a first-time cost analysis of current warfarin peri-procedural management practices, including a cost-effectiveness analysis (CEA) of predominant bridging vs predominant non-bridging practices. From the hospital perspective, a one-year decision-analytic model followed the cost and success consequences of the peri-procedural warfarin in a hypothetical cohort of 10,000 atrial fibrillation patients. Success was defined as survival with no adverse events. Outcome measures were the cost and success consequences of the 63% bridging (vs not-bridging) practice in the study setting, ie, Hamad Medical Corporation, Qatar, and the incremental cost-effectiveness ratio (ICER, cost/success) of the warfarin therapy when predominantly bridging based vs when predominantly non-bridging based. The model was based on Monte Carlo simulation, and sensitivity analyses were performed to confirm the robustness of the study conclusions. As per 63% bridging practices, the mean overall cost of peri-procedural warfarin management per patient was USD 3,260 (QAR 11,900), associated with an overall success rate of 0.752. Based on the CEA, predominant bridging was dominant (lower cost, higher effect) over the predominant non-bridging practice in 62.2% of simulated cases, with a cost-saving of up to USD 2,001 (QAR 7,303) at an average of USD 272 (QAR 993) and was cost-effective in 36.9% of cases. Being between cost-saving and cost-effective, compared to predominant non-bridging practices, the predominant use of bridging with warfarin seems to be a favorable strategy in atrial fibrillation patients.

2-Nitroallyl carbonate-based green bifunctional reagents for catalytic asymmetric annulation reactions

2-Nitroallylic carbonates, a new class of "green" 1,3-bielectrophilic reagents for organic synthesis and catalysis, have been prepared. The bifunctional tertiary amine-catalyzed asymmetric [3 + 3] annulations of cyclic enols with these reagents occur much faster than corresponding reactions with 2-nitroallylic esters and produce no acidic by-products poisoning the catalyst. Furthermore, 2-nitroallylic carbonates enable highly enantioselective one-pot synthesis of a variety of fused dihydropyrane derivatives from available precursors bearing pharmacophoric fragments.

Rivaroxaban versus low-molecular weight heparin plus warfarin prevents portal vein system thrombosis after splenectomy and pericardial devascularization: A randomized clinical trial

This study aimed to evaluate the safety and efficacy of rivaroxaban in preventing portal vein system thrombosis (PVST) in patients with liver cirrhosis after splenectomy and pericardial devascularization. 70 cirrhotic patients undergoing splenectomy and pericardial devascularization were randomly assigned to rivaroxaban treatment (n=35) or low-molecular weight heparin (LMWH) plus warfarin treatment (n=35) for 30 days in this randomized controlled trial. The primary endpoint is the PVST formation. Ultrasound doctors and radiologists were blinded to the randomization results. Both groups received routine outpatient inspection every month and were followed for one year. 17 patients (48.6 %) in rivaroxaban group developed PVST, compared with 27 patients (77.1 %) in LMWH plus warfarin group (P=0.025). The incidence of PVST during the first year postoperation was significantly lower in rivaroxaban group than in LMWH plus warfarin group (F=7.901, P=0.006). The intra-group comparisons versus baseline showed the liver function improved from POD 21 to POM 1, and coagulation function improved from POM 2, in rivaroxaban group. In contrast, the liver function improved from POM 1 to POM 2, and coagulation function improved from POM 4, in LMWH plus warfarin group. The prophylactic use of rivaroxaban significantly decreases the incidence of PVST after splenectomy and pericardial devascularization in cirrhotic patients compared to LMWH plus warfarin treatment. Besides, rivaroxaban treatment was safe and effective and associated with better liver and coagulation functions improvement than LMWH plus warfarin treatment.

Impact of PCSK9, WDR12, CDKN2A, and CXCL12 Polymorphisms in Jordanian Cardiovascular Patients on Warfarin Responsiveness and Sensitivity

Background

The main objective of this study is sought to determine the impacts of PCSK9, WDR12, CDKN2A, and CXCL12 polymorphisms on warfarin sensitivity and responsiveness in Jordanian cardiovascular patients during the initiation and stabilization phases of therapy.

Methods

This study took place at the anticoagulation clinic at Queen Alia Heart Institute (QAHI) in Jordan. DNA samples were collected from 212 cardiovascular patients and 213 healthy controls. Genomic SNPs genotyping was conducted using the MassARRAY System at the Australian Genome Research Facility.

Results

This study assessed 10 polymorphisms (rs11206510 within the PCSK9 gene, rs6725887 and rs7582720 within the WDR12 gene, rs4977574, rs10757278, and rs1333049 within the CDKN2A gene, rs2862116, rs7906426, rs1746048, and rs268322 within the CXCL12 gene) in 212 Jordanian cardiovascular patients. Carriers of CDKN2A rs1333049, rs10757278, and PCSK9 rs11206510 polymorphisms had an increased risk of resistance during the initiation phase of warfarin therapy compared to those who do not carry it, or those who are carrying one polymorphism only (P < 0.05), while carriers of CXCL12 rs7906426 polymorphism had similar increased risk but during the stabilization phase of warfarin therapy (P < 0.05).

Conclusion

Carriers of CXCL12 rs2862116 polymorphism had an increased risk to be warfarin extensive responders compared to those with no or only one polymorphism (P = 0.01). However, the presence of PCSK9 rs11206510 polymorphism affects the warfarin maintenance doses (P ˃ 0.0001).

Effects of Herba Erigerontis injection on pharmacodynamics and pharmacokinetics of warfarin in rats in vivo

Herba Erigerontis injection (HEI) is an aqueous solution derived from whole plants of Erigeron breviscapus, which may be co-administered with warfarin to treat cardiovascular and cerebrovascular disorders. This research was conducted to make sure whether HEI would affect anticoagulation of warfarin to guarantee reasonable medication. The pharmacodynamic study was designed to measure prothrombin time (PT) and activated partial thromboplastin time (APTT) values, and international normalized ratio (INR) values were calculated. For pharmacokinetic study, ultra performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS) technology was applied to measure plasma concentrations of warfarin enantiomers. The influence of HEI on plasma protein binding rate of warfarin was assessed by ultrafiltration. Pharmacodynamic study demonstrated that both HEI alone and co-administered with warfarin could increase PT and INR values significantly (P < .01), whereas the APTT values were unaffected (P > .05). Pharmacokinetic study manifested that C_max , AUC and t_1/2 prolonged significantly (P < .01) for R/S-warfarin in presence of HEI. Low (3.6 mL/kg), medium (7.2 mL/kg) and high (10.8 mL/kg) doses of HEI could decrease plasma protein binding rate of warfarin significantly (P < .01). The results mean that HEI can potentiate the anticoagulant response of warfarin through both pharmacodynamics and pharmacokinetics.

Comparison of cardiovascular response between patients on warfarin and hypertensive patients not on warfarin during dental extraction

OBJECTIVE

To evaluate cardiovascular response in patients on warfarin and hypertensive patients not on warfarin during dental extraction.

MATERIALS AND METHODS

This retrospective study included 53 patients who had undergone dental extraction while on warfarin (mean age 78.8 ± 6.3 years, 26 men) and 66 with hypertension who had undergone dental extraction but were not on warfarin (mean age 77.4 ± 6.8 years, 22 men). Vital signs were monitored in both groups during extraction.

RESULTS

The highest systolic blood pressure (SBP) values (mean 150.1 ± 21.1 mmHg) were observed in patients on warfarin before (9.0%) and after (10.3%) administration of local anesthesia (LA), during extraction (39.7%), and during (33.3%) and after (7.7%) suturing (n = 78; p < 0.01), and in hypertensive patients not receiving warfarin (160.6 ± 24.8 mmHg) before (19.2%) and after (27.3%) administration of LA, during extraction (29.3%), and during (18.2%) and after (6.1%) suturing (n = 99; p < 0.01). The highest SBP was linearly correlated with SBP before administration of LA in patients on warfarin (highest SBP = 0.9415 × SBP before LA + 23.243, R² = 0.75481) and in hypertensive patients not on warfarin (highest SBP = 1.0027 × SBP before LA + 15.789, R² = 0.60341).

CONCLUSIONS

The highest SBP was not distributed evenly between patients on warfarin and hypertensive patients not on warfarin during dental extraction and was strongly associated with SBP before LA regardless of anticoagulant status.

CLINICAL RELEVANCE

Thorough management of SBP is required in patients on warfarin to avoid thromboembolism and major hemorrhagic complications. Knowing the SBP value before dental treatment would help predict the risk of cardiovascular complications.

Pickles and warfarin interaction: a case-based review

A 36-year-old woman with a history of lupus and antiphospholipid syndrome controlled by warfarin presented to the hospital with left periorbital ecchymosis. She was found to have an INR of 9 despite maintaining her normal warfarin dose of 12.5 mg/15 mg alternating qd. The only identifiable precipitating factor was that the patient recently stopped eating dill pickles. Limiting dietary vitamin K while on warfarin therapy was once considered best practice. However, studies have demonstrated that maintaining a consistent intake of vitamin K is more important than the quantity. Still, many patients on warfarin remain unaware of which foods contain large amounts of vitamin K and are, therefore, susceptible to bleeding sequelae. Practitioners should be educated to inform patients to consume a steady amount of vitamin K in their diet, identify which foods contain vitamin K, and include pickles on that list.

Inhibitory effects of sesamin on CYP2C9-dependent 7-hydroxylation of S-warfarin

A recent report demonstrated that sesamin strongly and non-competitively inhibits S-warfarin 7-hydroxylation activity in human liver microsomes with a K_i value of 0.2 μM. This finding suggests that sesamin predominantly binds to CYP2C9 at another site for which it has a higher affinity than its affinity for the active site, thereby inhibiting the activity of CYP2C9 non-competitively. In this study, we found that sesamin competitively inhibited the 7-hydroxylation activity of S-warfarin in human liver microsomes with a K_i value of 15.7 μM. In addition, the recombinant CYP2C9-dependent 7-hydroxylation activity of S-warfarin was competitively inhibited by sesamin with a Ki value of 13.1 μM. These results are consistent with the fact that sesamin is a good substrate of CYP2C9, and its activity follows Michaelis-Menten kinetics. As the plasma concentration of sesamin after its administration is usually lower than 0.01 μM, the inhibition of S-warfarin metabolism by sesamin does not appear to be severe.

Vitamin K versus warfarin interruption alone in patients without bleeding and an international normalized ratio > 10

BACKGROUND

Reversal of an international normalized ratio (INR) > 10 with vitamin K is recommended in patients experiencing bleeding; however, information on outcomes with reversal using vitamin K in non-bleeding patients is lacking.

OBJECTIVE

To compare clinical and safety outcomes between non-bleeding patients receiving warfarin with an INR > 10 who did and did not receive a prescription for vitamin K.

PATIENTS/METHODS

This was a retrospective cohort study conducted in an integrated health-care delivery system. Adult patients receiving warfarin therapy who experienced an INR > 10 without bleeding between 01/01/2006 and 06/30/2018 were included. Patients were assessed for an outpatient dispensing or in-office administration of vitamin K on the day of or the day after an INR > 10 and then clinically relevant bleeding, thromboembolism, all-cause mortality, and time to INR < 4 within the next 30 days.

RESULTS

A total of 809 patients was included with 332 and 477 who were and were not dispensed vitamin K, respectively. Overall, mean patient age was 71.7 years, 60.1% were female and the mean INR was 10.4 at presentation. There were no differences between groups in 30-day rates of bleeding or thromboembolism (both P > .05). Patients dispensed vitamin K had a higher likelihood of mortality (15.1% versus 10.1%, P = .032, adjusted odds ratio = 1.63, 95% confidence interval 1.03 to 2.57). Overall, time to an INR < 4 was similar between groups.

CONCLUSION

Vitamin K administration was not associated with improved clinical outcomes in asymptomatic patients with an INR > 10.

[Pharmacist-led anticoagulation monitoring can significantly improve the effectiveness and safety of warfarin for patients during hospitalization]

OBJECTIVE

To investigate the role of pharmacist-led anticoagulation monitoring service for warfarin anticoagulation therapy in patients during hospitalization.

METHODS

We retrospectively analyzed the data of 421 patients receiving warfarin anticoagulation therapy during hospitalization between April, 2016 and December, 2017. Of these patients, 316 received daily pharmacist-led anticoagulation monitoring service including checking the patients' International Normalized Ratio (INR) and other pertinent laboratory test results and reviewing medication changes and the patients' clinical status (monitoring group); the other 105 patients receiving warfarin anticoagulation therapy without pharmaceutical care served as the control group. The data including compliance rate of anticoagulant indicators, incidence and rate of prompt management of INR alert, thrombosis and bleeding events during hospitalization were analyzed among these patients.

RESULTS

Compared with the control patients, the patients in the monitoring group showed a significantly higher percentage time within target INR range [(73.20±9.46)% vs (46.32±17.11)%, P &lt; 0.001] and a higher qualified rate of INR before discharge (98.42% vs 60.95%, P &lt; 0.001) as well as a higher proper INR-monitoring frequency (97.15% vs 66.67%, P &lt; 0.001). The patients in the monitoring group showed a significantly lower incidence of INR alert than the control patients (8.23% vs 20.00%, P &lt; 0.001) with also a much higher rate of prompt management (96.15% vs 33.33%). The two groups had similar incidences of clinical events except that the control group reported a higher incidence of minor bleeding episodes (9.52% vs 2.53%, P=0.005).

CONCLUSIONS

Pharmacist-led anticoagulation monitoring service can significantly improve the effectiveness and safety of warfarin anticoagulation therapy for patients during hospitalization.

Femoral Nerve Palsy Secondary to Iliopsoas Spontaneous Haematoma in a Patient Under Warfarin Treatment

Femoral nerve palsy secondary to iliopsoas non-traumatic haematoma is a scarce complication with a treatment approach that remains controversial between conservative and surgical intervention. We present a case of a 64-year-old male patient under warfarin medication, who developed severe left hip and anterior thigh pain and femoral nerve palsy with no history of trauma. Laboratory studies revealed a prolonged international normalized ratio level of 4.5, and imaging studies revealed a large haematoma surrounding the left iliopsoas muscle (35 cm x 9 cm x 6 cm). The patient was treated conservatively with discontinuation of his anticoagulation remedy and vitamin K administration and recovered almost fully after eight months, following a rehabilitation programme. Patients who are on anticoagulants should raise a high index of suspicion. Conservative management can provide a good outcome; it requires, however, a long period of rehabilitation.

Impact of CYP2C9, VKORC1, ApoE and ABCB1 polymorphisms on stable warfarin dose requirements in elderly Chinese patients

Aim: To analyze the impact of nongenetic factors and gene polymorphisms on warfarin dose requirements in elderly Shanghai Han Chinese patients. Materials & methods: Genotypes of CYP2C9 (rs1799853 and rs1057910), FPGS (rs7856096), ApoE (rs7412 and rs429358), GGCX (rs699664 and rs12714145), EPHX1 (rs4653436, rs1877724, rs1051740 and rs1131873), NQO1 (rs1800566 and rs10517), ABCB1 (rs1045642), VKORC1 (rs9923231) and CYP4F2 (rs2108622) in 214 patients with stable warfarin dose were determined and their demographic characteristics were recorded. Results: Multiple linear regression analysis revealed that VKORC1 rs9923231, CYP2C9*3 rs1057910, ApoE rs7412, age, BMI and concomitant amiodarone could explain 37.0% of the individual variations of daily stable warfarin dose. Conclusion: VKORC1 rs9923231, CYP2C9*3 rs1057910, ApoE rs7412, age, BMI and concomitant amiodarone play an important role in stable dose variation of warfarin in elderly Shanghai Han Chinese patients, whereas ABCB1 rs1045642 is not a significant genetic factor.

An observational study of international normalized ratio control according to NICE criteria in patients with non-valvular atrial fibrillation: the SAIL Warfarin Out of Range Descriptors Study (SWORDS)

AIMS 

In patients with non-valvular atrial fibrillation prescribed warfarin, the UK National Institute of Health and Care Excellence (NICE) defines poor anticoagulation as a time in therapeutic range (TTR) of <65%, any two international normalized ratios (INRs) within a 6-month period of ≤1.5 ('low'), two INRs ≥5 within 6 months, or any INR ≥8 ('high'). Our objectives were to (i) quantify the number of patients with poor INR control and (ii) describe the demographic and clinical characteristics associated with poor INR control.

METHOD AND RESULTS

Linked anonymized health record data for Wales, UK (2006-2017) was used to evaluate patients prescribed warfarin who had at least 6 months of INR data. 32 380 patients were included. In total, 13 913 (43.0%) patients had at least one of the NICE markers of poor INR control. Importantly, in the 24 123 (74.6%) of the cohort with an acceptable TTR (≥65%), 5676 (23.5%) had either low or high INR readings at some point in their history. In a multivariable regression female gender, age (≥75 years), excess alcohol, diabetes heart failure, ischaemic heart disease, and respiratory disease were independently associated with all markers of poor INR control.

CONCLUSION 

Acceptable INR control according to NICE standards is poor. Of those with an acceptable TTR (>65%), one-quarter still had unacceptably low or high INR levels according to NICE criteria. Thus, only using TTR to assess effectiveness with warfarin has the potential to miss a large number of patients with non-therapeutic INRs who are likely to be at increased risk.

The effect of genetic and nongenetic factors on warfarin dose variability in Qatari population

The objective of this study is to estimate the prevalence of VKORC1, CYP2C9, and CYP4F2 genetic variants and their contribution to warfarin dose variability in Qataris. One hundred and fifty warfarin-treated Qatari patients on a stable dose and with a therapeutic INR for at least three consecutive clinic visits were recruited. Saliva samples were collected using Oragene DNA self-collection kit, followed by DNA purification and genotyping via TaqMan Real-Time-PCR assay. The population was stratified into derivation and validation cohorts for the dosing model. The minor allele frequency (MAF) of VKORC1 (-1639G>A) was A (0.47), while the MAF's for the CYP2C9*2 and *3 and CYP4F2*3 were T (0.12), C (0.04) and T (0.43), respectively. Carriers of at least one CYP2C9 decreased function allele (*2 or *3) required lower median (IQR) warfarin doses compared to noncarriers [24.5 (14.5) mg/week vs. 35 (21) mg/week, p < 0.001]. Similarly, carriers of each additional copy of (A) variant in VKORC1 (-1639G>A) led to reduction in warfarin dose requirement compared to noncarriers [21(7.5) vs. 31.5(18.7) vs. 43.7(15), p < 0.0001]. CYP4F2*3 polymorphism on the other hand was not associated with warfarin dose. Multivariate analysis on the derivation cohort (n = 104) showed that a dosing model consisting of hypertension (HTN), heart failure (HF), VKORC1 (-1639G>A), CYP2C9*2 & *3, and smoking could explain 39.2% of warfarin dose variability in Qataris (P < 0.001). In the validation cohort (n = 45), correlation between predicted and actual warfarin doses was moderate (Spearman's rho correlation coefficient = 0.711, p < 0.001). This study concluded that VKORC1 (-1639G>A), CYP2C9*2 & *3 are the most significant predictors of warfarin dose along with HTN, HF and smoking.

Use of simplified HAS-BLED score in patients with atrial fibrillation receiving warfarin

BACKGROUND

Oral anticoagulant drugs are proven to prevent thromboembolism in patients with atrial fibrillation (AF). To date, HAS-BLED score is used to assess bleeding risk. This study was conducted to compare simplified HAS-BLED (sHAS-BLED) with conventional HAS-BLED (cHAS-BLED) scores.

METHODS

This retrospective study recruited patients with AF receiving warfarin among July 2013 to December 2018 in Central Chest Institute of Thailand. The cHAS-BLED score used the time in therapeutic range less than 70% as labile INR, whereas sHAS-BLED score used SAMe-TT2R2 score of 3 or more as a substitute for labile INR. A paired Student's t test was used to compare sHAS-BLED and cHAS-BLED. The Pearson's correlation was used to assess the correlation of sHAS-BLED to cHAS-BLED scores. The Bland-Altman plot was used to confirm the agreement of individual sHAS-BLED to cHAS-BLED score.

RESULTS

A total of 126 AF patients were enrolled. The average age, SAMe-TT2R2 score, and cHAS-BLED score were 70.52 ± 10.37 years, 3.53 ± 1.03, and 2.03 ± 0.95, respectively. The sHAS-BLED score was not statistically significantly different compared with cHAS-BLED score (P = .08). The sHAS-BLED and cHAS-BLED scores had a very strong correlation with a correlation coefficient of .86 (P < .01). The Bland-Altman plot was performed to confirm the agreement of individual sHAS-BLED to cHAS-BLED scores.

CONCLUSIONS

The sHAS-BLED was not statistically significantly different compared with cHAS-BLED and can be used in clinical practice. However, larger clinical trial will be needed to prove whether sHAS-BLED can predict bleeding risk in the future.

A Retrospective Propensity Score-Matched Early Thromboembolic Event Analysis of Prothrombin Complex Concentrate vs Fresh Frozen Plasma for Warfarin Reversal Prior to Emergency Neurosurgical Procedures

BACKGROUND

Reversal of therapeutic anticoagulation prior to emergency neurosurgical procedures is required in the setting of intracranial hemorrhage. Multifactor prothrombin complex concentrate (PCC) promises rapid efficacy but may increase the probability of thrombotic complications compared to fresh frozen plasma (FFP).

OBJECTIVE

To compare the rate of thrombotic complications in patients treated with PCC or FFP to reverse therapeutic anticoagulation prior to emergency neurosurgical procedures in the setting of intracranial hemorrhage at a level I trauma center.

METHODS

Sixty-three consecutive patients on warfarin therapy presenting with intracranial hemorrhage who received anticoagulation reversal prior to emergency neurosurgical procedures were retrospectively identified between 2007 and 2016. They were divided into 2 cohorts based on reversal agent, either PCC (n = 28) or FFP (n = 35). The thrombotic complications rates within 72 h of reversal were compared using the χ2 test. A multivariate propensity score matching analysis was used to limit the threat to interval validity from selection bias arising from differences in demographics, laboratory values, history, and clinical status.

RESULTS

Thrombotic complications were uncommon in this neurosurgical population, occurring in 1.59% (1/63) of treated patients. There was no significant difference in the thrombotic complication rate between groups, 3.57% (1/28; PCC group) vs 0% (0/35; FFP group). Propensity score matching analysis validated this finding after controlling for any selection bias.

CONCLUSION

In this limited sample, thrombotic complication rates were similar between use of PCC and FFP for anticoagulation reversal in the management of intracranial hemorrhage prior to emergency neurosurgical procedures.

'Enemy within': an interesting cause for anemia during warfarin therapy for atrial fibrillation

The oral anticoagulant warfarin is a vitamin K antagonist and is considered the first line anticoagulant in valvular atrial fibrillation. However prothrombin time should be closely monitored, drug interactions checked and compliance regarding diet ensured when the patient is on warfarin therapy. Anaemia should be looked for, evaluated for the cause and corrected since it is an independent predictor of bleeding and thrombotic episodes during warfarin therapy for atrial fibrillation We present an interesting case of anaemia which developed during warfarin therapy for atrial fibrillation. The patient was on amiodarone and was consuming leafy vegetables resulting in frequent raise in prothrombin time during which time she developed bleeding into the right femoral pseudoaneurysm which had developed following catheterisation for thrombectomy. Surgical correction of pseudoaneurysm was done, comedication was changed and diet compliance ensured which resulted in the subsequent maintenance of prothrombin time in the therapeutic range and steady haemoglobin levels.

Comparison of the Effects of Indobufen and Warfarin in a Rat Model of Adenine-Induced Chronic Kidney Disease

Background

Worldwide, the treatment of patients with chronic kidney disease (CKD) remains a challenge as warfarin treatment can be associated with severe adverse events related to bleeding. Alternative anticoagulants that can be used in CKD remain to be identified. This study aimed to compare the effects of indobufen, a new antiplatelet agent, with warfarin in a rat model of adenine-induced CKD.

Material/Methods

Forty-eight male Wistar rats were treated with intragastric adenine to create the rat model of CKD and were divided into four groups: an untreated control group (N=12), a group treated with dimethyl sulfoxide (DMSO) (N=12), a group treated with indobufen, (N=12) and a group treated with warfarin (N-12). Treatment was given for 4 weeks and 8 weeks. Kidney histology was performed, and the degree of fibrosis was quantified using Masson trichrome staining.

Results

In the rat model of adenine-induced CKD, Masson trichrome staining showed that the degree of kidney fibrosis in the indobufen group (26%) was significantly reduced (p<0.05) when compared the DMSO group (58%) and the warfarin group (49%). Kidney fibrosis was associated with upregulation of 6-keto-PGI2/TXB2 in the rat kidney tissue.

Conclusions

In a rat model of adenine-induced CKD, preliminary findings showed that indobufen was associated with reduced kidney fibrosis when compared with warfarin.

Effects of CYP2C11 gene knockout on the pharmacokinetics and pharmacodynamics of warfarin in rats

1. CYP2C11 is the most abundant isoform of cytochrome P450s (CYPs) in male rats and is considered the main enzyme for warfarin metabolism. 2. To further access the in vivo function of CYP2C11 in warfarin metabolism and efficacy, a CYP2C11-null rat model was used to study warfarin metabolism with both in vitro and in vivo approaches. Prothrombin time (PT) of warfarin was also determined. 3. The maximum rate of metabolism (V_max) and intrinsic clearance (CL_int) of liver microsomes from CYP2C11-null males were reduced by 37 and 64%, respectively, compared to those in Sprague Dawley (S-D) rats. The K_m of liver microsomes from CYP2C11-null males was increased by 73% compared to that of S-D rats. The time to reach the maximum plasma concentration (T_max) of warfarin in CYP2C11-null males was significantly delayed compared to that in S-D males, and the CL rate was also reduced. The PT of CYP2C11-null rats was moderately longer than that of S-D rats. 4. In conclusion, the clearance rate of warfarin was mildly decreased and its anticoagulant effect was moderately increased in male rats following CYP2C11 gene knockout. CYP2C11 played a certain role in the clearance and efficacy of warfarin, while it did not seem to be essential.

Evaluation of the predictive performance of Bayesian dosing for warfarin in Chinese patients

Aim: To evaluate the accuracy and predictive performance of Bayesian dosing for warfarin in Chinese patients. Materials & methods: Six multiple linear regression algorithms (Wei, Lou, Miao, Huang, Gage and IWPC) and a Bayesian method implemented in Warfarin Dose Calculator were compared with each other. Results: Six multiple linear regression warfarin dosing algorithms had similar predictive ability, except Miao and Lou. The mean prediction error of Bayesian priori and posteriori method were 0.01 mg/day (95% CI: -0.18 to 0.19) and 0.17 mg/day (95% CI: -0.05 to 0.29), respectively, and Bayesian posteriori method demonstrated better performance in all dose ranges. Conclusion: The Bayesian method showed a good potential for warfarin maintenance dose prediction in Chinese patients requiring less than 6 mg/day.

Bleeding Complications in Warfarin-Treated Patients Admitted to the Emergency Department

Background

Increased use of warfarin for the treatment and prophylaxis of many diseases has increased the frequency of adverse events. Emergency departments (EDs) are the first places where early interventions for bleeding and other complaints related to warfarin use are performed. This study assessed the characteristics of patients receiving warfarin and the risk factors for bleeding complication among those admitted to the ED.

Methods

Patients admitted to the ED for any reason other than trauma during a 1-year period were retrospectively reviewed. The study population consisted of 96 patients who had received warfarin and had an international normalized ratio (INR) ≥ 3. Patient demographics and medical history were recorded.

Results

The mean age of the patients (female, 52.1%) was 64.9 ± 14.5 years. Fatigue was the most common presenting complaint (61%). At least one major and/or minor bleeding event had occurred in 32 (33.3%) of the patients. Patients with (n = 32) and without (n = 64) bleeding complications did not significantly differ with respect to age, sex, reason for warfarin initiation, duration of warfarin use, concomitant diseases, and concurrent medications. There were also no significant differences in the distribution of patient admissions in terms of season at presentation, INR level, and weekly warfarin dose.

Conclusions

While the parameters evaluated in this study did not significantly differ among warfarin-treated patients, they may nonetheless pose a risk of bleeding. Further large-scale and long-term studies that take into account biological variation are required to precisely identify the risk factors for bleeding.

Follow-up and management of valvular heart disease patients with prosthetic valve: a clinical practice guideline for Indian scenario

PURPOSE

Valvular heart disease (VHD) patients after prosthetic valve implantation are at risk of thromboembolic events. Follow-up care of patients with prosthetic valve has a paramount role in reducing the morbidity and mortality. Currently, in India, there is quintessential need to stream line the follow-up care of prosthetic valve patients. This mandates the development of a consensus guideline for the antithrombotic therapy in VHD patients post prosthetic valve implantation.

METHODS

A national level panel was constituted comprising 13 leading cardio care experts in India who thoroughly reviewed the up to date literature, formulated the recommendations, and developed the consensus document. Later on, extensive discussions were held on this draft and the recommendations in 8 regional meetings involving 79 additional experts from the cardio care in India, to arrive at a consensus. The final consensus document is developed relying on the available evidence and/or majority consensus from all the meetings.

RESULTS

The panel recommended vitamin K antagonist (VKA) therapy with individualized target international normalized ratio (INR) in VHD patients after prosthetic valve implantation. The panel opined that management of prosthetic valve complications should be personalized on the basis of type of complications. In addition, the panel recommends to distinguish individuals with various co-morbidities and attend them appropriately.

CONCLUSIONS

Anticoagulant therapy with VKA seems to be an effective option post prosthetic valve implantation in VHD patients. However, the role for non-VKA oral therapy in prosthetic valve patients and the safety and efficacy of novel oral anticoagulants in patients with bioprosthetic valve need to be studied extensively.

Selected Food/Herb-Drug Interactions: Mechanisms and Clinical Relevance

BACKGROUND

Food/Herb-drug interactions have become a major problem in health care. These interactions can lead to loss of therapeutic efficacy or toxic effects of drugs.

AREAS OF UNCERTAINTY

To probe the clinical relevance of such interactions, the impact of food/herb intake on the clinical effects of drug administration has to be evaluated. Failure to identify and efficiently manage food-drug interactions can lead to serious consequences. A comprehensive knowledge of the mechanisms that underpin variability in disposition will help optimize therapy.

DATA SOURCES

Electronic search of literatures from relevant databases were conducted. A total of 58 original scientific reports/review articles were obtained with the search strategy; of which 25 were found eligible to be included in the present review. Required data were extracted from these studies, and their methodologies were assessed.

RESULTS AND CONCLUSIONS

This review updates our knowledge on clinical food-drug interactions with emphasis on mechanism and clinical implications. Results obtained from literature search identified interactions with selected foods/herbs generated from in vivo and in vitro studies. For example, interaction studies in humans revealed a reduction in the bioavailability of mercaptopurine when taken concurrently with substances containing xanthine oxidase (eg, cow milk); a reduction in the bioavailability of quinine with Garcinia kola; increased bioavailability/toxicity of felodipine, nifedipine, saquinavir, sildenafil with grape juice; increased bioavailability of felodipine, cisapride with red wine and diminished bioavailability of fexofenadine with apple. Pharmacokinetic and/or pharmacodynamic mechanisms are implicated in many of these interactions. By evaluating the dietary patterns of patients and use of prescribed medications, health professionals will be well informed of potential interactions and associated adverse effects.

Effects of vitamin K epoxide reductase complex 1 gene polymorphisms on warfarin control in Japanese patients with left ventricular assist devices (LVAD)

PURPOSE

This study aimed to investigate relationships between times in therapeutic range (TTR) or warfarin sensitivity indexes (WSI) and VKORC1-1639G>A and CYP2C9 polymorphisms in patients with left ventricular assist devices (LVAD).

METHODS

Severe heart failure patients who received LVAD from January 1, 2013 to October 31, 2017 were recruited. Relationships between TTR or WSI and VKORC1-1639G>A and CYP2C9 gene polymorphisms were investigated immediately after LVAD implantation (period 1) and immediately prior to hospital discharge (period 2).

RESULTS

Among 54 patients, 31 (72.1%) had VKORC1-1639AA and CYP2C9*1/*1 (AA group) polymorphisms and 12 (27.9%) had VKORC1-1639GA and CYP2C9*1/*1 (GA group) polymorphisms. During period 1, mean prothrombin time-international normalized ratio (PT-INR) values were significantly higher in the AA group than in the GA group (2.21 vs. 2.05, p < 0.0001). Mean WSI values were 1.68-fold greater in the AA group than in the GA group (1.14 vs. 0.68, p < 0.0001). In addition, times below the therapeutic range (TBTR) in the GA group were significantly greater than in the AA group during period 1 (39.8 vs. 28.3%, p = 0.032), and insufficient PT-INR was more frequent in the GA group than in the AA group. However, mean PT-INR values during period 2 did not differ and no significant differences in TTR, TATR, and TBTR values were identified. In subsequent multivariable logistic regression analyses, the VKORC1-1639GA allele was significantly associated with insufficient anticoagulation.

CONCLUSION

Patients with the VKORC1-1639GA and CYP2C9*1/*1 alleles may receive insufficient anticoagulation therapy during the early stages after implantation of LVAD, and VKORC1-1639G>A and CYP2C9 genotyping may contribute to more appropriate anticoagulant therapy after implantation of LVAD.

A New Approach towards Minimizing the Risk of Misdosing Warfarin Initiation Doses

It is a challenge to be able to prescribe the optimal initial dose of warfarin. There have been many studies focused on an efficient strategy to determine the optimal initial dose. Numerous clinical, genetic, and environmental factors affect the warfarin dose response. In practice, it is common that the initial warfarin dose is substantially different from the stable maintenance dose, which may increase the risk of bleeding or thrombosis prior to achieving the stable maintenance dose. In order to minimize the risk of misdosing, despite popular warfarin dose prediction models in the literature which create dose predictions solely based on patients' attributes, we have taken physicians' opinions towards the initial dose into consideration. The initial doses selected by clinicians, along with other standard clinical factors, are used to determine an estimate of the difference between the initial dose and estimated maintenance dose using shrinkage methods. The selected shrinkage method was LASSO (Least Absolute Shrinkage and Selection Operator). The estimated maintenance dose was more accurate than the original initial dose, the dose predicted by a linear model without involving the clinicians initial dose, and the values predicted by the most commonly used model in the literature, the Gage clinical model.

Signal detection for bleeding associated with the use of direct oral anticoagulants

PURPOSE

The potential link between serious or life-threatening bleeding and the use of direct oral anticoagulants (DOACs) was evaluated.

METHODS

Qualitative and quantitative reviews of case reports of bleeding events involving dabigatran, rivaroxaban, apixaban, edoxaban, and warfarin through March 31, 2017, were performed. A disproportionality analysis was conducted for each DOAC using an empirical Bayesian approach based on the relative reporting rate. Subanalyses were performed to assess (1) bleeding events (including mortality and life-threatening events) associated with DOACs among all adverse-event reports and (2) warfarin-related bleeding events. These analyses were conducted based on clinical definitions from the Medical Dictionary for Regulatory Activities.

RESULTS

During the Food and Drug Administration Adverse Event Reporting System (FAERS) review period, 35 adverse-event terms (in any system organ class) with a disproportionality score (EB₀₅) of >7.5 for DOACs were identified; this accounted for 40,109 adverse-event reports. Adverse events with the highest disproportionality scores included atrial thrombosis, increased factor X level, dysfunctional uterine bleeding, high-frequency ablation, pericardial hemorrhage, and internal hemorrhage. Adverse events with the highest EB₀₅ (>5) included internal hemorrhage, hemorrhage, and exsanguination; events with the greatest number of patient experiences included hemorrhage (6,881 events), internal hemorrhage (2,569 events), and hematoma (1,995 events). Warfarin-related events (including death or life-threatening events) were also assessed. A total of 8,729 adverse events were associated with warfarin use. The most common of these included hemorrhage (6,225 events), hematoma (2,199 events), and internal hemorrhage (270 events).

CONCLUSION

The disproportionality analysis of the FAERS database suggests a quantitative signal between DOAC use and life-threatening or serious bleeding.