Drug-Drug Interactions in the Treatment of Cancer-Associated Venous Thromboembolism with Direct Oral Anticoagulants.

Venous thromboembolism (VTE) is a frequent complication of cancer, and management of cancer-associated thrombosis (CAT) is challenging due to increased risks of bleeding and recurrent VTE. Recent trials have shown an acceptable efficacy and safety of direct oral anticoagulants (DOACs) in the treatment of CAT compared to low-molecular weight heparin. Although DOACs provide an effective and convenient treatment option in CAT, the need to assess the risk of drug-drug interactions (DDI) with antineoplastic therapies poses a barrier to their use in clinical practice. With the aim of supporting the assessment of CAT patients for treatment with DOAC, this review provides a comprehensive overview of the compatibility of antineoplastic therapies with the individual DOACs (apixaban, dabigatran, edoxaban, and rivaroxaban). Using several data sources, we characterized 100 widely used antineoplastic agents with regard to their effect on p-glycoprotein and cytochrome P450, both important in the transport and elimination of DOACs. This enabled us to evaluate 400 "DOAC-antineoplastic agent"-pairs regarding their likelihood to interact (unlikely, potential, or likely), ultimately leading to clinical recommendations on the appropriateness of concomitant use for each pair. A potential or likely DDI was identified for 12% of the evaluated pairs. For nearly all antineoplastic agents, at least one DOAC was considered compatible.

Design and synthesis of dabigatran etexilate derivatives with inhibiting thrombin activity for hepatocellular carcinoma treatment.

Hepatocellular carcinoma (HCC) is one of the most fatal solid malignancies worldwide. Evidence suggests that thrombin stimulates tumor progression via fibrin formation and platelet activation. Meanwhile, we also found a correlation between thrombin and HCC through bioinformatics analysis. Dabigatran is a selective, direct thrombin inhibitor that reversibly binds to thrombin. Dabigatran was used as the lead agent in this study, and 19 dabigatran derivatives were designed and synthesized based on docking mode. The thrombin-inhibitory activity of the derivative AX-2 was slightly better than that of dabigatran. BX-2, a prodrug of AX-2, showed a fairly strong inhibitory effect on thrombin-induced platelet aggregation, and effectively antagonized proliferation of HCC tumor cells induced by thrombin at the cellular level. Furthermore, BX-2 reduced tumor volume, weight, lung metastasis, and secondary tumor occurrence in nude mouse models. BX-2 combined with sorafenib increased sorafenib efficacy. This study lays the foundation for discovering new anti-HCC mechanism based on thrombin. BX-2 can be used as an anti-HCC drug lead for further research.

Optimal management of cardiac surgery patients using direct oral anticoagulants: recommendations for clinical practice.

OBJECTIVES: Literature is scarce on the management of patients using direct oral anticoagulants (DOACs) undergoing elective, urgent and emergency surgery. Therefore, we summarize the current evidence and provide literature-based recommendations for the management of patients on DOACs in the perioperative phase. METHODS: A general literature review was conducted on the pharmacology of DOACs and for recommendations on the management of cardiac surgical patients on DOACs. Additionally, we performed a systematic review for studies on the use of direct DOAC reversal agents in the emergency cardiac surgical setting. RESULTS: When surgery is elective, the DOAC cessation strategy is relatively straightforward and should be adapted to the renal function. The same approach applies to urgent cases, but additional DOAC activity drug level monitoring tests may be useful. In emergency cases, idarucizumab can be safely administered to patients on dabigatran in any of the perioperative phases. However, andexanet alfa, which is not registered for perioperative use, should not be administered in the preoperative phase to reverse the effect of factor Xa inhibitors, as it may induce temporary heparin resistance. Finally, the administration of (activated) prothrombin complex concentrate may be considered in all patients on DOACs, and such concentrates are generally readily available. CONCLUSIONS: DOACs offer several advantages over vitamin K antagonists, but care must be taken in patients undergoing cardiac surgery. Although elective and urgent cases can be managed relatively straightforwardly, the management of emergency cases requires particular attention.

DOAC plasma concentration upon hospital admission in a cohort of trauma patients. An observational real-life study.

PURPOSE: Due to a better safety profile, direct oral anticoagulants (DOACs) are increasingly prescribed for prevention of thromboembolic events. However, little is known about DOAC plasma concentrations in trauma patients upon hospital admission. Thus, we investigated the frequency and extent of DOAC possible over- and underdosing in trauma patients upon hospital admission. METHODS: In this single-center retrospective study, DOAC plasma concentrations of adult trauma patients were analyzed with specific calibrated anti-IIa (dabigatran) and anti-Xa (apixaban, edoxaban and rivaroxaban) tests within 4 h after hospital admission. RESULTS: A total of 210 trauma patients, admitted between 2019 and 2022, were included in the analyses. Low DOAC levels < 30 ng/mL were detected in 13.3% of the patients. In 7.1% of the patients, DOAC plasma levels ranged between 300-399 ng/mL and further 7.1% exhibited plasma concentrations > 400 ng/mL. The highest incidence of high to very high DOAC plasma concentration was observed for patients on rivaroxaban and dabigatran. A moderate correlation was observed between dabigatran plasma concentration and estimated glomerular filtration rate (rho = - 0.5338, p = 0.0003). For rivaroxaban no clear association between plasma concentration and liver or renal function could be detected. Patients on statins had significantly higher DOAC concentration in comparison with those not taking statins (153 (76-274) vs 108 (51-217) ng/mL, p = 0.046). CONCLUSION: The current study revealed that patients on dabigatran and rivaroxaban were prone to higher DOAC plasma levels upon hospital admission in comparison with apixaban and edoxaban. DOAC plasma level measurement in trauma patients might be warranted due to unpredictively low or high plasma concentrations. However, the clinical impact of altered plasma levels on both, bleeding and thromboembolic events, remains to be determined by future studies.

Electrochemical Disposable Biosensor to Monitor Dabigatran in Point-of-Care Anticoagulation Therapy.

Dabigatran etexilate, an oral prodrug, is often used to treat complications linked to thrombosis. Dabigatran (DAB, active form) does not need to be monitored. However, there are several conditions, such as reduced renal function, traumatic bleeding, emergency surgery, the need for thrombolytic therapy in acute stroke, or the requirement to use other forms of anticoagulation, where knowing the concentration of DAB in the blood is indispensable. Unfortunately, there are no convenient DAB-specific point-of-care tests available. To solve this problem, two disposable sensors were constructed and optimised in this work to detect the anticoagulant drug DAB using novel co-facing disposable electrodes, which allows a calibration-free quantitation of the electroactive mediator concentration. A trypsin-based sensor was evaluated. This sensor performed well in a 10 mM Tris buffer (pH 8.8) solution. However, trypsin was inhibited by alpha-1 antitrypsin when a plasma sample was introduced into the sensor. This problem was overcome by plasma filtration. This sensor showed a detection limit of 50.7 ng mL-1 DAB in plasma and a quantification range of 177-500 ng mL-1. A thrombin-based sensor was also constructed. This sensor performed well in ten-fold diluted plasma, overcoming the filtration problem observed with the trypsin-based sensor. This sensor showed a detection limit of 9.6 ng mL-1 DAB in plasma and a quantification range of 11.5-140 ng mL-1. Its extensive pH stability range, the possibility of working at physiological pH, low volume, low cost, and fast turnaround response (less than 20 s) make the calibration-free thrombin-based sensor a suitable point-of-care test to measure DAB concentration in the blood.

The effects of coagulation factors and their inhibitors on proliferation and migration in colorectal cancer.

BACKGROUND/AIM: Clotting factors promote cancer development. We investigated if coagulation proteins promote proliferation and migration in colorectal cancer (CRC) cell lines and whether their direct inhibitors can attenuate these effects. MATERIALS AND METHODS: DLD-1 and SW620 cells were treated with tissue factor (0, 50, 100 and 500 pg/mL ± 10 µg/mL 10H10 [anti-tissue factor antibody]), thrombin (0.0, 0.1, 1.0 and 10.0 U/mL ± 0.5 µM dabigatran [thrombin inhibitor]) and Factor Xa, FXa (0.0, 0.1, 1.0 and 10.0 U/mL ± 100 ng/mL rivaroxaban [FXa inhibitor]) and their effects on proliferation and migration were quantified using the PrestoBlue® and transwell migration assays, respectively. RESULTS: Thrombin increased proliferation from 48 h treatment compared to its control (48 h 6.57 ± 1.36 u vs. 2.42 ± 0.13 u, p = 0.001, 72 h 9.50 ± 1.54 u vs. 4.50 ± 0.47 u, p = 0.004 and 96 h 10.77 ± 1.72 u vs. 5.57 ± 0.25 u, p = 0.008). This increase in proliferation was attenuated by dabigatran at 72 h (2.23 ± 0.16 u vs. 3.26 ± 0.43 u, p = 0.04). Tissue factor (0 pg/mL 20.7 ± 1.6 cells/view vs. 50 pg/mL 32.4 ± 1.9 cells/view, p = 0.0002), FXa (0.0 U/mL 8.9 ± 1.1 cells/view vs. 10.0 U/mL 17.7 ± 1.7 cells/view, p < 0.0001) and thrombin (0.0 U/mL 8.9 ± 1.3 cells/view vs. 10.0 U/mL 20.2 ± 2.0 cells/view, p < 0.0001) all increased migration compared to their controls. However, their direct inhibitors did not attenuate these increases. CONCLUSION: Thrombin, FXa and TF all increase migration in CRC in vitro. Thrombin induced increase in proliferation is abrogated by dabigatran. Dabigatran may have potential as an anti-cancer therapy in CRC.

When and How to Use Reversal Agents for Direct Oral Anticoagulants?

PURPOSE OF REVIEW: Our objective is to describe currently available reversal agents for direct oral anticoagulants (DOACs), their target population, the available clinical practice recommendations and future directions. RECENT FINDINGS: Specific (idarucizumab for dabigatran and andexanet alfa for direct factor Xa inhibitors) and non-specific (prothrombin complex concentrates) reversal agents are effective in neutralizing the anticoagulant effect of DOACs. New investigational antidotes such as ciraparantag and VMX-C001 offer an alternative to andexanet alfa in reversing the anticoagulant activity of direct oral factor Xa inhibitors, but more clinical data are needed before they could be licensed for use. Specific reversal agents are recommended for use in clinical situations within their licensed indications (i.e.: reversal of DOACs in patients with severe uncontrolled or life-threatening bleeding or in need of emergency surgery or other invasive procedures), while non-specific reversal agents may be used when specific antidotes are not available or indicated.

Periprocedural Management of Patients With Atrial Fibrillation Receiving a Direct Oral Anticoagulant Undergoing a Digestive Endoscopy.

INTRODUCTION: The periprocedural management of patients with atrial fibrillation (AF) using a direct oral anticoagulant (DOAC) undergoing elective gastrointestinal (GI) endoscopic procedure remains uncertain. We investigated the safety of a standardized periprocedural DOAC management strategy. METHODS: The Periprocedural Anticoagulation Use for Surgery Evaluation cohort study enrolled adult patients receiving a DOAC (apixaban, rivaroxaban, or dabigatran) for AF scheduled for an elective procedure or surgery. This analysis addresses patients undergoing digestive endoscopy. Standardized periprocedural management consisted of DOAC interruption 1 day preendoscopy with resumption 1 day after procedure at low-moderate risk of bleeding or 2 days in case of a high bleeding risk. Thirty-day outcomes included GI bleeding, thromboembolic events, and mortality. RESULTS: Of 556 patients on a DOAC (mean [SD] age of 72.5 [8.6] years; 37.4% female; mean CHADS 2 score 1.7 [1.0]), 8.6% were also on American Society of Anesthesiology (ASA) and 0.7% on clopidogrel. Most of the patients underwent colonoscopies (63.3%) or gastroscopies (14.0%), with 18.9% having both on the same procedural day. The mean total duration of DOAC interruption was 3.9 ± 1.6 days. Four patients experienced an arterial thromboembolic event (0.7%, 0.3%-1.8%) within 24.2 ± 5.9 days of DOAC interruption. GI bleeding events occurred in 2.5% (1.4%-4.2%) within 11.1 ± 8.1 days (range: 0.6; 25.5 days) of endoscopy, with major GI bleeding in 0.9% (0.4%-2.1%). Three patients died (0.5%; 0.2%-1.6%) 15.6-22.3 days after the endoscopy. DISCUSSION: After a contemporary standardized periprocedural management strategy, patients with AF undergoing DOAC therapy interruption for elective digestive endoscopy experienced low rates of arterial thromboembolism and major bleeding.

Dabigatran etexilate is efficacious in consumptive coagulopathy and pain associated with venous malformations.

OBJECTIVE: Consumptive coagulopathy treatment and pain management are crucial for patients with venous malformations (VMs). Dabigatran etexilate, a non-vitamin K antagonist oral anticoagulant, has known advantages compared with low-molecular-weight heparin and vitamin K antagonists, including oral administration, a more consistent pharmacokinetics/pharmacodynamics profile, a better safety profile, and no need for coagulation surveillance. In the present study, we tested the efficacy and safety of dabigatran etexilate for consumptive coagulopathy treatment and pain management for patients with VMs. METHODS: To investigate the efficacy and safety of dabigatran etexilate in treating localized intravascular coagulation (LIC) associated with VM, we retrospectively collected data for 19 outpatients with VM and LIC, who had been treated with dabigatran etexilate from September 2019 to June 2021. The patients provided oral informed consent and underwent biologic blood testing, routine examinations, and determination of coagulation function before and after treatment. The dosage of dabigatran etexilate was 110 mg twice daily for adults and 55 mg twice daily for children. RESULTS: All 19 patients had benefited from dabigatran etexilate treatment with coagulation improvement and pain relief. Pain had improved in all 16 evaluable patients. The fibrinogen and D-dimer levels had improved in 18 of 19 patients. The fibrin degradation product level had improved in 10 of 14 patients. None of patients reported lesion regression, appearance changes, or improvement in mobility. No significant differences were found in the D-dimer, fibrinogen, and fibrin degradation product levels between the short-term (<10 days) and long-term (≥10 days) use of the medication. Dabigatran etexilate was well tolerated by all patients. No bleeding event had occurred during follow-up. CONCLUSIONS: The results of our study have confirmed the efficacy and safety of dabigatran etexilate in treating pain and LIC in patients with VMs. Dabigatran etexilate is a suitable choice preoperatively to modify coagulation function and pain in patients with VMs.

Assessment of DOAC in GEriatrics (Adage Study): Rivaroxaban/Apixaban Concentrations and Thrombin Generation Profiles in NVAF Very Elderly Patients.

BACKGROUND: Although a growing number of very elderly patients with atrial fibrillation (AF), multiple conditions, and polypharmacy receive direct oral anticoagulants (DOACs), few studies specifically investigated both apixaban/rivaroxaban pharmacokinetics and pharmacodynamics in such patients. AIMS: To investigate: (1) DOAC concentration-time profiles; (2) thrombin generation (TG); and (3) clinical outcomes 6 months after inclusion in very elderly AF in-patients receiving rivaroxaban or apixaban. METHODS: Adage-NCT02464488 was an academic prospective exploratory multicenter study, enrolling AF in-patients aged ≥80 years, receiving DOAC for at least 4 days. Each patient had one to five blood samples at different time points over 20 days. DOAC concentrations were determined using chromogenic assays. TG was investigated using ST-Genesia (STG-ThromboScreen, STG-DrugScreen). RESULTS: We included 215 patients (women 71.1%, mean age: 87 ± 4 years), 104 rivaroxaban and 111 apixaban, and 79.5% receiving reduced-dose regimen. We observed important inter-individual variabilities (coefficient of variation) whatever the regimen, at C max [49-46%] and C min [75-61%] in 15 mg rivaroxaban and 2.5 mg apixaban patients, respectively. The dose regimen was associated with C max and C min plasma concentrations in apixaban (p = 0.0058 and p = 0.0222, respectively), but not in rivaroxaban samples (multivariate analysis). Moreover, substantial variability of thrombin peak height (STG-ThromboScreen) was noticed at a given plasma concentration for both xabans, suggesting an impact of the underlying coagulation status on TG in elderly in-patients. After 6-month follow-up, major bleeding/thromboembolic event/death rates were 6.7%/1.0%/17.3% in rivaroxaban and 5.4%/3.6%/18.9% in apixaban patients, respectively. CONCLUSION: Our study provides original data in very elderly patients receiving DOAC in a real-life setting, showing great inter-individual variability in plasma concentrations and TG parameters. Further research is needed to understand the potential clinical impact of these findings.

Acute Pulmonary Embolism: A Review.

Importance: Pulmonary embolism (PE) is characterized by occlusion of blood flow in a pulmonary artery, typically due to a thrombus that travels from a vein in a lower limb. The incidence of PE is approximately 60 to 120 per 100 000 people per year. Approximately 60 000 to 100 000 patients die from PE each year in the US. Observations: PE should be considered in patients presenting with acute chest pain, shortness of breath, or syncope. The diagnosis is determined by chest imaging. In patients with a systolic blood pressure of at least 90 mm Hg, the following 3 steps can be used to evaluate a patient with possible PE: assessment of the clinical probability of PE, D-dimer testing if indicated, and chest imaging if indicated. The clinical probability of PE can be assessed using a structured score or using clinical gestalt. In patients with a probability of PE that is less than 15%, the presence of 8 clinical characteristics (age <50 years, heart rate <100/min, an oxygen saturation level of > 94%, no recent surgery or trauma, no prior venous thromboembolism event, no hemoptysis, no unilateral leg swelling, and no estrogen use) identifies patients at very low risk of PE in whom no further testing is needed. In patients with low or intermediate clinical probability, a D-dimer level of less than 500 ng/mL is associated with a posttest probability of PE less than 1.85%. In these patients, PE can be excluded without chest imaging. A further refinement of D-dimer threshold is possible in patients aged 50 years and older, and in patients with a low likelihood of PE. Patients with a high probability of PE (ie, >40% probability) should undergo chest imaging, and D-dimer testing is not necessary. In patients with PE and a systolic blood pressure of 90 mm Hg or higher, compared with heparin combined with a vitamin K antagonist such as warfarin followed by warfarin alone, direct oral anticoagulants such as apixaban, edoxaban, rivaroxaban, or dabigatran, are noninferior for treating PE and have a 0.6% lower rate of bleeding. In patients with PE and systolic blood pressure lower than 90 mm Hg, systemic thrombolysis is recommended and is associated with an 1.6% absolute reduction of mortality (from 3.9% to 2.3%). Conclusions and Relevance: In the US, PE affects approximately 370 000 patients per year and may cause approximately 60 000 to 100 000 deaths per year. First-line therapy consists of direct oral anticoagulants such as apixaban, edoxaban, rivaroxaban, or dabigatran, with thrombolysis reserved for patients with systolic blood pressure lower than 90 mm Hg.

Ameliorative Effect of Dabigatran on CFA-Induced Rheumatoid Arthritis via Modulating Kallikrein-Kinin System in Rats.

Rheumatoid arthritis is an autoimmune disease that affects joints, leading to swelling, inflammation, and dysfunction in the joints. Recently, research efforts have been focused on finding novel curative approaches for rheumatoid arthritis, as current therapies are associated with adverse effects. Here, we examined the effectiveness of dabigatran, the antithrombotic agent, in treating complete Freund's adjuvant (CFA)-induced arthritis in rats. Subcutaneous injection of a single 0.3 mL dosage of CFA into the rat's hind leg planter surface resulted in articular surface deformities, reduced cartilage thickness, loss of intercellular matrix, and inflammatory cell infiltration. There were also increased levels of the Anti-cyclic citrullinated peptide antibody (ACPA), oxidative stress, and tissue Receptor activator of nuclear factor-kappa B ligand (RANKL). Proteins of the kallikrein-kinin system (KKS) were also elevated. The inhibitory effects of dabigatran on thrombin led to a subsequent inhibition of KKS and reduced Toll-like receptor 4 (TLR4) expression. These effects also decreased RANKL levels and showed anti-inflammatory and antioxidant effects. Therefore, dabigatran could be a novel therapeutic strategy for arthritis.

Dabigatran and Wet AMD, Results From Retinal Pigment Epithelial Cell Monolayers, the Mouse Model of Choroidal Neovascularization, and Patients From the Medicare Data Base.

Background: Age-related macular degeneration (AMD), the leading cause of irreversible blindness in elderly Caucasian populations, includes destruction of the blood-retina barrier (BRB) generated by the retinal pigment epithelium-Bruch's membrane complex (RPE/BrM), and complement activation. Thrombin is likely to get access to those structures upon BRB integrity loss. Here we investigate the potential role of thrombin in AMD by analyzing effects of the thrombin inhibitor dabigatran. Material and Methods: MarketScan data for patients aged ≥65 years on Medicare was used to identify association between AMD and dabigatran use. ARPE-19 cells grown as mature monolayers were analyzed for thrombin effects on barrier function (transepithelial resistance; TER) and downstream signaling (complement activation, expression of connective tissue growth factor (CTGF), and secretion of vascular endothelial growth factor (VEGF)). Laser-induced choroidal neovascularization (CNV) in mouse is used to test the identified downstream signaling. Results: Risk of new wet AMD diagnosis was reduced in dabigatran users. In RPE monolayers, thrombin reduced TER, generated unique complement C3 and C5 cleavage products, led to C3d/MAC deposition on cell surfaces, and increased CTGF expression via PAR1-receptor activation and VEGF secretion. CNV lesion repair was accelerated by dabigatran, and molecular readouts suggest that downstream effects of thrombin include CTGF and VEGF, but not the complement system. Conclusions: This study provides evidence of association between dabigatran use and reduced exudative AMD diagnosis. Based on the cell- and animal-based studies, we suggest that thrombin modulates wound healing and CTGF and VEGF expression, making dabigatran a potential novel treatment option in AMD.

Efficacy and Safety Considerations With Dose-Reduced Direct Oral Anticoagulants: A Review.

Importance: Dose-reduced regimens of direct oral anticoagulants (DOACs) may be used for 2 main purposes: dose-adjusted treatment intended as full-intensity anticoagulation (eg, for stroke prevention in atrial fibrillation [AF] in patients requiring dose reduction) or low-intensity treatment (eg, extended-duration treatment of venous thromboembolism [VTE]). We reviewed randomized clinical trials (RCTs) to understand the scenarios in which dose-adjusted or low-intensity DOACs were tested and reviewed the labeled indications by regulatory authorities, using data from large registries to assess whether the use of dose-reduced DOACs in routine practice aligned with the findings of RCTs. Observations: Among 4191 screened publications, 35 RCTs that used dose-adjusted DOACs were identified for dabigatran, apixaban, rivaroxaban, and edoxaban. Of these 35 RCTs, 29 were related to stroke prevention in AF. Efficacy and safety results for dose-adjusted DOACs in large RCTs of AF were similar to those found for full-dose DOACs. To our knowledge, dabigatran, apixaban, and rivaroxaban have not been studied as dose-adjusted therapy for acute VTE treatment. Low-intensity DOACs were identified in 37 RCTs. Low-intensity DOACs may be used for extended-duration treatment of VTE (apixaban and rivaroxaban), primary prevention in orthopedic surgeries (dabigatran, apixaban, and rivaroxaban), primary prevention in ambulatory high-risk cancer patients (apixaban and rivaroxaban) or (postdischarge) high-risk medical patients (rivaroxaban), in stable atherosclerotic vascular disease, or after a recent revascularization for peripheral artery disease in conjunction with aspirin (rivaroxaban). Minor variations exist between regulatory authorities in different regions regarding criteria for dose adjustment of DOACs. Data from large registries indicated that dose-reduced DOACs were used occasionally with doses or for clinical scenarios different from those studied in RCTs or recommended by regulatory authorities. Conclusions and Relevance: Dose adjustment and low-intensity treatment are 2 different forms of dose-reduced DOACs. Dose adjustment is mostly relevant for AF and should be done based on the approved criteria. Dose adjustment of DOACs should not be used for acute VTE treatment in most cases. In contrast, low-intensity DOACs may be used for primary or secondary VTE prevention for studied and approved indications. Attention should be given to routine practice patterns to align the daily clinical practice with existing evidence of safety and efficacy.

Predictors of Recurrent Stroke After Embolic Stroke of Undetermined Source in the RE-SPECT ESUS Trial.

Background We sought to determine recurrent stroke predictors among patients with embolic strokes of undetermined source (ESUS). Methods and Results We applied Cox proportional hazards models to identify clinical features associated with recurrent stroke among participants enrolled in RE-SPECT ESUS (Randomized, Double-Blind, Evaluation in Secondary Stroke Prevention Comparing the Efficacy and Safety of the Oral Thrombin Inhibitor Dabigatran Etexilate Versus Acetylsalicylic Acid in Patients With Embolic Stroke of Undetermined Source) trial, an international clinical trial evaluating dabigatran versus aspirin for patients with ESUS. During a median follow-up of 19 months, 384 of 5390 participants had recurrent stroke (annual rate, 4.5%). Multivariable models revealed that stroke or transient ischemic attack before the index event (hazard ratio [HR], 2.27 [95% CI, 1.83-2.82]), creatinine clearance <50 mL/min (HR, 1.69 [95% CI, 1.23-2.32]), male sex (HR, 1.60 [95% CI, 1.27-2.02]), and CHA2DS2-VASc ≥4 (HR, 1.55 [95% CI, 1.15-2.08] and HR, 1.66 [95% CI, 1.21-2.26] for scores of 4 and ≥5, respectively) versus CHA2DS2-VASc of 2 to 3, were independent predictors for recurrent stroke. Conclusions In RE-SPECT ESUS trial, expected risk factors previously linked to other common stroke causes were associated with stroke recurrence. These data help define high-risk groups for subsequent stroke that may be useful for clinicians and for researchers designing trials among patients with ESUS. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02239120.

The changing use of anticoagulants in New Zealand.

AIMS: To assess the change in the use of oral anticoagulants in New Zealand over 10 years since the introduction of dabigatran and rivaroxaban. METHODS: Data were collected from the National Pharmaceutical database from January 2011 to March 2021. Seven and a half million prescriptions for oral anticoagulants were analysed. RESULTS: The total number of people taking oral anticoagulants increased from 46,000 in July 2011 to 105,000 by March 2021. The growth was predominantly from the increased use of direct oral anticoagulants (DOACs). Initially, dabigatran was the only funded DOAC in New Zealand; approximately 50,000 people were taking this medication by August 2018, when rivaroxaban was introduced. Subsequent growth has predominantly been from rivaroxaban, with 23,000 users by March 2021. Warfarin use has dropped by 50% over the last 10 years. CONCLUSIONS: The introduction of the DOACs was expected to reduce the use of warfarin. However, the rapid rise in DOAC use was not predicted. The increase is most likely in patients with atrial fibrillation with the positive benefit of reducing the incidence of embolic stroke. However, having a high proportion of the elderly population (15% of people over 75-years) on anticoagulants has implications for the health sector, making hospital admissions and surgery more complex.

Pharmacological Difference Between Platelet Aggregations in Cardioembolic Stroke Patients with Direct Oral Anticoagulants: A Pilot Study.

Background Selecting the appropriate direct oral anticoagulants (DOACs) for embolic ischemic stroke patients, especially on concurrent antiplatelet therapy, is important. However, a limited number of studies have reported on the pharmacological differences in platelet aggregation of each DOAC. We aimed to evaluate the antiplatelet effects of selected DOACs, by comparing dabigatran (a direct oral thrombin inhibitor) and factor Xa (FXa) inhibitors (apixaban and rivaroxaban) in patients who had suffered a cardioembolic stroke. Methods We retrospectively evaluated 12 patients diagnosed with a cardioembolic stroke who took any DOAC without an antiplatelet drug and underwent platelet aggregation tests within 60 days from the onset of symptoms. The platelet aggregation tests were analyzed by both light transmission aggregometry and VerifyNow®. Results Six patients (50%) took dabigatran, while the other six (50%) took an FXa inhibitor (n = 4 for apixaban and n = 2 for rivaroxaban). From the light transmission aggregometry analysis, it was found that the maximal extent of aggregation for adenosine diphosphate (ADP) was significantly higher with dabigatran than with FXa inhibitors, and the ED50 value of ADP on platelet aggregation was significantly lower with dabigatran than with FXa inhibitors. Moreover, the VerifyNow® analyses revealed that P2Y12 reaction units were significantly higher with dabigatran than with FXa inhibitors. Conclusions Dabigatran had little impact on platelet aggregation compared to FXa inhibitors in patients who had suffered a cardioembolic stroke with atrial fibrillation, and who took DOACs for secondary prevention within 60 days from the onset.

Anticoagulation in Atrial Fibrillation Associated with Mitral Stenosis.

Rheumatic valve disease is present in 0.4 % of the word population, mainly in lowincome countries. Rheumatic mitral stenosis affects more women and between 40 to 75 % of patients may have atrial fibrillation (AF), more frequently in upper-middle income countries. This rhythm disturbance is due to increased atrial pressure, chronic inflammation, fibrosis, and left atrial enlargement. There is also an increase in the prevalence of AF with age in patients with mitral stenosis. The risk of stroke is 4 % per year. Success rates for cardioversion, Cox-Maze procedure, and catheter ablation are low. Therefore, anticoagulation with vitamin K antagonist is mandatory for Evaluated Heart valves, Rheumatic or Artificial (EHRA) classification type 1. However, this anticoagulation is used by less than 80 % of those eligible and less than 30 % have the international normalized ratio in the therapeutic range. The safety and efficacy of using rivaroxaban, a direct factor Xa inhibitor anticoagulant, were demonstrated in the RIVER trial with a sample of 1005 patients with AF and bioprosthetic mitral valve. The indication for valve replacement, that is, if severe mitral stenosis or severe mitral regurgitation, was not specified. A randomized, open-label study (DAVID-MS) is underway to compare the effectiveness and safety of dabigatran and warfarin therapy for stroke prevention in patients with AF and moderate or severe mitral stenosis. Thus, the applicability of the use of direct anticoagulants in patients with AF and mitral stenosis and also in those undergoing mitral bioprostheses surgery will be the subject of further studies. The findings may explain if specific atrial changes of mitral stenosis even after the valve replacement will influence thromboembolic events with direct anticoagulants.

Appropriateness of inpatient dosing of direct oral anticoagulants for atrial fibrillation.

Direct oral anticoagulant (DOAC) use for stroke prevention in atrial fibrillation (AF) has dose reduction criteria including age, weight, serum creatinine, and creatinine clearance. There is a paucity of data for rates of inappropriate inpatient DOAC dosing in Australia. The objective was to determine the rates of inappropriate inpatient DOAC dosing in AF and identifying its associated underlying factors. We conducted a retrospective cross-sectional study from December 2013 to November 2019 across six South Australian public hospitals utilising a centralised electronic health record. Multivariate analysis was used to identify factors associated with underdosing of patients prescribed apixaban. Of 1882 inpatients, 544 (28.9 %) were inappropriately dosed. Underdosing was the most common form of inappropriate dosing with rates of 22.9 % (n = 295), 7.1 % (n = 7), and 25.1 % (n = 124) for apixaban, dabigatran, and rivaroxaban, respectively. Independent factors predictive of apixaban underdosing included higher age (adjusted odds ratio (aOR) 1.63 [95 % Confidence Interval (CI): 1.47-1.81]), higher serum creatinine (aOR 1.13 [95 % CI: 1.08-1.19]), higher total number of drugs on discharge (aOR 1.08 [95 % CI: 1.04-1.11]), and being already prescribed a DOAC on admission (aOR 1.63 [95 % CI: 1.12-2.38]). Nearly one quarter of all apixaban prescribing was inappropriately underdosed. Older patients with multimorbidity, frailty and polypharmacy present a challenge for clinicians in balancing risks of thromboembolism and bleeding. It is likely prescribers are more conservative in their apixaban dosing in this population. Clinicians should consider alternative drug regimens to avoid DOAC use at inappropriate doses at unknown safety and efficacy.

Determinants for under- and overdosing of direct oral anticoagulants and physicians' implementation of clinical pharmacists' recommendations.

AIMS: To analyse the appropriateness of direct oral anticoagulant (DOAC) dosing and determinants for under-and overdosing as well as acceptance and implementation rates of pharmacists' interventions. METHODS: Cross-sectional study in a tertiary hospital in hospitalized patients with atrial fibrillation on DOACs in 2019 (n = 1688). Primary outcome was the proportion of patients with inappropriate DOAC prescribing with identification of determinants for under-and overdosing. Secondary outcomes included acceptance and implementation rates of pharmacists' recommendations and determination of reasons for nonacceptance/nonimplementation. RESULTS: Inappropriate prescribing was observed in 16.9% of patients (n = 286) with underdosing (9.7%) being more prevalent than overdosing (6.9%). For all DOACs considered together, body weight<60 kg (odds ratio [OR] 0.46 [0.27-0.77]), edoxaban use (OR 0.42 [0.24-0.74]), undergoing surgery (OR 0.57 [0.37-0.87]) and being DOAC naïve (OR 0.45 [0.29-0.71]) were associated with significantly lower odds of underdosing. Bleeding history (OR 1.86 [1.24-2.80]) and narcotic use (OR 1.67 [1.13-2.46]) were associated with significantly higher odds for underdosing. Determinants with a significantly higher odds of overdosing were renal impairment (OR 11.29 [6.23-20.45]) and body weight<60 kg (OR 2.34 [1.42-3.85]), whereas dabigatran use (OR 0.24 [0.08-0.71]) and apixaban (OR 0.18 [0.10-0.32]) were associated with a significantly lower odds of overdosing compared to rivaroxaban. Physicians accepted the pharmacists' advice in 179 cases (79.2%) consisting of 92 (51.4%) recommendations for underdosing, 82 (45.8%) for overdosing and 5 (2.8%) for contraindications. CONCLUSION: Inappropriate DOAC prescribing remains common, although there is a slight improvement compared to our study of 2016. Clinical services led by pharmacists help physicians to reduce the number of inadequate prescriptions for high-risk medications such as DOACs.