Monitoring anticoagulation with argatroban in critically ill patients: activated partial thromboplastin time versus diluted thrombin time

Anticoagulation with argatroban using hemoclot™ targets is safe and effective in CARDS patients receiving venovenous extracorporeal membrane oxygenation: An exploratory bi-centric cohort study

Direct thrombin inhibitors, including argatroban, are increasingly used for anticoagulation during venovenous extracorporeal membrane oxygenation (VV ECMO). In many centers activated partial thromboplastin time (aPTT) is used for monitoring, but it can be affected by several confounders. The aim of this study was to evaluate the safety and efficacy of anticoagulation with argatroban titrated according to diluted thrombin time targets (hemoclot™ assay) compared to anti-Xa guided anticoagulation with unfractionated heparin (UFH).

METHODS

This cohort study included adults at two tertiary care centers who required VV ECMO for severe COVID-19-related acute respiratory distress syndrome (CARDS). Patients received center-dependent argatroban or UFH for anticoagulation during ECMO. Argatroban was guided following a hemoclot™ target range of 0.4-0.6 μg/ml. UFH was guided by anti-factor Xa (antiXa) levels (0.2-0.3 IU/ml). The primary outcome was safety of argatroban compared to UFH, assessed by time to first clinically relevant bleeding event or death during ECMO. Secondary outcomes included efficacy (time to thromboembolism) and feasibility (proportion of anticoagulation targets within range).

RESULTS

From 2019 to 2021 57 patients were included in the study with 27 patients (47 %) receiving argatroban and 30 patients (53 %) receiving UFH. The time to the first clinically relevant bleeding or death during ECMO was similar between groups (HR (argatroban vs. UFH): 1.012, 95 % CI 0.44-2.35, p = 0.978). Argatroban was associated with a decreased risk for thromboembolism compared to UFH (HR 0.494 (95 % CI 0.26-0.95; p = 0.034)). The overall proportion of anticoagulation within target ranges was not different between groups (46 % (23-54 %) vs. 46 % (37 %-57 %), p = 0.45).

CONCLUSION

Anticoagulation with argatroban according to hemoclot™ targets (0.4-0.6 μg/ml) compared to antiXa guided UFH (0.2-0.3 IU/ml) is safe and may prolong thromboembolism-free time in patients with severe ARDS requiring VV ECMO.

Thrombosis prophylaxis following trauma

PURPOSE OF REVIEW

This review explores the persistent occurrence of venous thromboembolic events (VTE) in major trauma patients despite standard thrombosis prophylaxis with low-molecular-weight heparin (LMWH) or unfractionated heparin (UFH). It investigates the inadequacies of standard pharmacologic prophylaxis and proposes alternative approaches not covered in current trauma guidelines.

RECENT FINDINGS

Recent studies highlight the effectiveness of monitoring and adjusting subcutaneous LMWH doses based on anti-Xa levels for the purpose of reducing VTE in trauma patients. The need for dose adaptation arises due to factors like fluctuating organ function, varying antithrombin levels, interaction with plasma proteins, and altered bioavailability influenced by oedema or vasopressor use. Additionally, promising alternatives such as intravenous LMWH, UFH, and argatroban have shown success in intensive care settings.

SUMMARY

The standard dosing of subcutaneous LMWH is often insufficient for effective thrombosis prophylaxis in trauma patients. A more personalised approach, adjusting doses based on specific effect levels like anti-Xa or choosing an alternative mode of anticoagulation, could reduce the risk of insufficient prophylaxis and subsequent VTE.

Novel Monitoring and Dose Adjustment of Argatroban, a Direct Thrombin Inhibitor, to Maintain Therapeutic Anticoagulation in a Patient With Antiphospholipid Antibody Syndrome, Heparin-Induced Thrombocytopenia, and COVID-19 Pneumonia

In patients who require systemic anticoagulation, a reliable monitoring method is required to ensure anticoagulation is maintained within the correct therapeutic window and patients are treated appropriately. When titrating direct thrombin inhibitors (DTIs), dilute thrombin time (dTT) measurements have been demonstrated to be more reliable and accurate than activated partial thromboplastin time (aPTT) measurements and thus often the preferred DTI assessment. However, a clinical need arises when both dTT measurements are not readily available and aPTT measurements are unreliable.

CASE SUMMARY

A 57-year-old woman with a history of antiphospholipid antibody syndrome, heparin-induced thrombocytopenia, and multiple prior deep venous thromboses and pulmonary emboli was admitted with COVID-19 pneumonia and intubated due to hypoxic respiratory failure. Argatroban was initiated in place of her home medication warfarin. However, the patient had a prolonged aPTT value at baseline and overnight dTT assay measurements were limited at our institution. A multidisciplinary team of hematology and pharmacy clinicians created a modified patient-specific aPTT target range and argatroban dosing was titrated accordingly. Subsequent aPTT values in the modified target range corresponded to therapeutic dTT values, indicating therapeutic anticoagulation was successfully achieved and maintained. Patient blood samples were additionally evaluated retrospectively using an investigational novel point-of-care test that detected and quantified the argatroban anticoagulant effect.

CONCLUSIONS

Therapeutic anticoagulation with a DTI in a patient with unreliable aPTT measurements can be achieved with use of a modified patient-specific aPTT target range. Early validation of an investigational rapid testing alternative for DTI monitoring is promising.

Monitoring Direct Thrombin Inhibitors With Calibrated Diluted Thrombin Time vs Activated Partial Thromboplastin Time in Pediatric Patients

OBJECTIVES

Activated partial thromboplastin time (aPTT) is the primary test used to monitor intravenous (IV) direct thrombin inhibitors (DTIs) but has many limitations. The plasma diluted thrombin time (dTT) has shown better correlation with DTI levels than aPTT. This study compared dose-response curves for dTT and aPTT in pediatric patients receiving argatroban and bivalirudin.

METHODS

A retrospective review of pediatric patients treated with argatroban (n = 45) or bivalirudin (n = 14) monitored with dTT and aPTT.

RESULTS

The dTT assay was calibrated to report DTI concentrations in µg/mL for argatroban and bivalirudin with good analytic sensitivity and specificity. The dTT was fivefold more likely to show a stable dose-response slope than the aPTT (P < .0002; odds ratio, 4.9). For patients in whom both dTT and aPTT showed a significant correlation between dose and assay results, dTT had a higher average correlation factor compared with aPTT (P = .007). Argatroban dose-response slopes showed more inter- and intrapatient variation than bivalirudin (dose-response slope coefficient of variation, 132% vs 52%).

CONCLUSIONS

The dTT assay was more likely to show a stable dose response and have a stronger correlation with DTI dose than aPTT. Argatroban shows more variation in dose response than bivalirudin.

Caution in Using the Activated Partial Thromboplastin Time to Monitor Argatroban in COVID-19 and Vaccine-Induced Immune Thrombocytopenia and Thrombosis (VITT)

Introduction

Argatroban is licensed for patients with heparin-induced thrombocytopenia and is conventionally monitored by activated partial thromboplastin time (APTT) ratio. The target range is 1.5 to 3.0 times the patients’ baseline APTT and not exceeding 100 s, however this baseline is not always known. APTT is known to plateau at higher levels of argatroban, and is influenced by coagulopathies, lupus anticoagulant and raised FVIII levels. It has been used as a treatment for COVID-19 and Vaccine-induced Immune Thrombocytopenia and Thrombosis (VITT). Some recent publications have favored the use of anti-IIa methods to determine the plasma drug concentration of argatroban.

Methods

Plasma of 60 samples from 3 COVID-19 patients and 54 samples from 5 VITT patients were tested by APTT ratio and anti-IIa method (dilute thrombin time dTT). Actin FS APTT ratios were derived from the baseline APTT of the patient and the mean normal APTT.

Results

Mean APTT ratio derived from baseline was 1.71 (COVID-19), 1.33 (VITT) compared to APTT ratio by mean normal 1.65 (COVID-19), 1.48 (VITT). dTT mean concentration was 0.64 µg/ml (COVID-19) 0.53 µg/ml (VITT) with poor correlations to COVID-19 baseline APTT ratio r² = 0.1526 p <0.0001, mean normal r² = 0.2188 p < 0.0001; VITT baseline APTT ratio r² = 0.04 p < 0.001, VITT mean normal r² = 0.0064 p < 0.001.

Conclusions

We believe that dTT is a superior method to monitor the concentration of argatroban, we have demonstrated significant differences between APTT ratios and dTT levels, which could have clinical impact. This is especially so in COVID-19 and VITT.

Evaluation of intravenous direct thrombin inhibitor monitoring tests: Correlation with plasma concentrations and clinical outcomes in hospitalized patients

The parenterally administered direct thrombin inhibitors (DTIs) argatroban and bivalirudin are effective anticoagulants for acute heparin-induced thrombocytopenia (HIT) treatment. The activated partial thromboplastin time (aPTT) has classically been used as the monitoring test to assess degree of anticoagulation, however concerns exist with using aPTT to monitor DTI therapy. In this observational study plasma samples from DTI treated patients were analyzed by aPTT, dilute thrombin time (dTT) and ecarin chromogenic assay (ECA) to delineate results into concordant and discordant groups. Discordant samples were further analyzed via liquid chromatography with tandem mass spectrometry (LC MS/MS). In total 101 patients with 198 samples were evaluated. Discordance between tests were frequent (59% of DTI treated patients). Bivalirudin aPTT vs dTT discordance was observed in 45% (57/126) of samples. Amongst bivalirudin samples with test discordance dTT results were more likely to be concordant with LC MS/MS than the aPTT (77% vs 9%, p < 0.0001). Argatroban aPTT vs dTT discordance was observed in 43% (31/72) and aPTT vs ECA discordance was observed in 40% (29/72) of samples. Amongst argatroban samples with test discordance both the dTT and ECA tests were more likely to have concordant results with LC MS/MS than the aPTT (88% vs 9%, p < 0.0001 for both dTT and ECA tests). There were no differences between discordant and concordant patient groups in a composite outcome of bleeding/thrombosis rate (23% vs 27%, p = 0.689). Further investigation is warranted to elucidate the effect of suitable monitoring assays on patient outcomes in the setting of DTI therapy.

Monitoring of argatroban and lepirudin anticoagulation in critically ill patients by conventional laboratory parameters and rotational thromboelastometry - a prospectively controlled randomized double-blind clinical trial

Background

Argatroban or lepirudin anticoagulation therapy in patients with heparin induced thrombocytopenia (HIT) or HIT suspect is typically monitored using the activated partial thromboplastin time (aPTT). Although aPTT correlates well with plasma levels of argatroban and lepirudin in healthy volunteers, it might not be the method of choice in critically ill patients. However, in-vivo data is lacking for this patient population.

Therefore, we studied in vivo whether ROTEM or global clotting times would provide an alternative for monitoring the anticoagulant intensity effects in critically ill patients.

Methods

This study was part of the double-blind randomized trial “Argatroban versus Lepirudin in critically ill patients (ALicia)”, which compared critically ill patients treated with argatroban or lepirudin. Following institutional review board approval and written informed consent, for this sub-study blood of 35 critically ill patients was analysed. Before as well as 12, 24, 48 and 72 h after initiation of argatroban or lepirudin infusion, blood was analysed for aPTT, aPTT ratios, thrombin time (TT), INTEM CT,INTEM CT ratios, EXTEM CT, EXTEM CT ratios and maximum clot firmness (MCF) and correlated with the corresponding plasma concentrations of the direct thrombin inhibitor.

Results

To reach a target aPTT of 1.5 to 2 times baseline, median [IQR] plasma concentrations of 0.35 [0.01–1.2] μg/ml argatroban and 0.17 [0.1–0.32] μg/ml lepirudin were required. For both drugs, there was no significant correlation between aPTT and aPTT ratios and plasma concentrations. INTEM CT, INTEM CT ratios, EXTEM CT, EXTEM CT ratios, TT and TT ratios correlated significantly with plasma concentrations of both drugs. Additionally, agreement between argatroban plasma levels and EXTEM CT and EXTEM CT ratios were superior to agreement between argatroban plasma levels and aPTT in the Bland Altman analysis. MCF remained unchanged during therapy with both drugs.

Conclusion

In critically ill patients, TT and ROTEM parameters may provide better correlation to argatroban and lepirudin plasma concentrations than aPTT.

Trial registration

ClinicalTrials.gov, NCT00798525, registered on 25 Nov 2008

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0475-y) contains supplementary material, which is available to authorized users.

Argatroban and Bivalirudin for Perioperative Anticoagulation in Cardiac Surgery

Argatroban and bivalirudin are used as replacement anticoagulants for heparin. The authors review clinical studies for these drugs in the perioperative setting of cardiac surgical patients including extracorporeal management and mechanical support therapy.

An ultrafiltration and high performance liquid chromatography coupled with diode array detector and mass spectrometry approach for screening and characterizing thrombin inhibitors from Rhizoma Chuanxiong

Thrombin (THR) plays a significant role in thromboembolic diseases, direct THR inhibitors are a class of important clinical anticoagulant drugs. This study established a THR in-solution based biospecific extraction combined with ultrafiltration and high performance liquid chromatography coupled with diode array detector and mass spectrometry analysis (TUA) method to screen and identify ligands for THR in Rhizoma Chuanxiong. After evaluating the reliability of the present TUA method using positive (argatroban) and negative (adenosine, tirofiban, ticagrelor) control drugs, this method was successfully applied to detect eight potential active compounds in Rhizoma Chuanxiong. Two new THR-targeted compounds isochlorogenic acid C and senkyunolide I with high THR inhibitory activity (IC50 206.48 and 197.23μM, respectively) were identified by liquid chromatography/mass spectrometry and enzyme inhibitory activity test finally. They were reported with direct THR inhibition activity for the first time and their ligand-THR interactions were explored by in silico molecular docking research. In addition, based on the TUA screening result, four compounds gained similar structure with the two hit compounds were also investigated as promising candidates targeting THR with high binding energy (>5.0kcal/mol). These results may prove that the proposed method could effectively screen THR inhibitors in complex mixtures.