Monitoring of low dabigatran concentrations: diagnostic performance at clinically relevant decision thresholds

Comparisons between diluted thrombin time, ecarin chromogenic assays, and UPLC-MS for plasma level dabigatran quantification: Results from DRIVING study

INTRODUCTION

The knowledge of dabigatran levels is helpful for decision-making in specific situations such as urgent surgery or when the question of reversal arises (uncontrolled bleeding, eligibility for thrombolysis). However, a limited number of observational studies are available regarding comparisons between quantification methods. The objective of the study was to compare dabigatran plasma levels using three assays including the reference method (high-performance liquid chromatography coupled with mass spectrometry), focusing on the agreement around the 30-50 ng/mL clinically relevant thresholds.

METHODS

Sixty healthy volunteers from DRIVING trial (NCT01627665) were given a single 300-mg dabigatran etexilate dose. Serial blood samplings were performed at pre-defined time points (0 to 24 h). We analyzed plasma samples using ultra-performance-liquid chromatography coupled with tandem mass spectrometry (UPLC-MS) (dabigatran reference method); ii/diluted thrombin time (dTT) (Hemoclot-DTI-Hyphen-Biomed); iii/ecarin-based chromogenic assay (ECA-II-Stago).

RESULTS

Nine hundred sixty samples were analyzed using the three assays (2759 values). dTT and ECA-II values were highly correlated with those of UPLC-MS (Deming regression). Most values >50 ng/mL were higher using dTT and ECA-II compared to UPLC-MS: biases were constant, +14% and +16% with dTT and ECA-II, respectively (Bland-Altman plots), suggesting that active metabolites accounted for ~15% of thrombin inhibition. Regarding values <30 ng/mL, 30-50 ng/mL, or ≥50 ng/mL, the agreement probability between dTT and ECA-II was of 90.6% [88.4-92.5] (Cohen's kappa coefficient 0.84).

CONCLUSION

dTT and ECA-II assays rapidly provide accurate dabigatran-level results for clinical practice, both assays being suitable in emergency, taking into account the thrombin inhibitory effect of dabigatran metabolites.

Direct Oral Anticoagulants: Laboratory Challenges and Antidotes

The use of direct oral anticoagulants (DOACs) is increasing in patients needing treatment of venous thromboembolism (VTE) and stroke prevention in atrial fibrillation (SPAF). This is due to the net clinical benefit in comparison to vitamin K antagonists (VKAs). The rise in DOAC use is accompanied by a remarkable reduction in heparin and VKA prescriptions. However, this rapid change in anticoagulation patterns brought new challenges to patients, prescribers, laboratories, and emergency physicians. Patients have new liberties concerning nutritional habits and comedication and no longer need frequent monitoring or dose adjustments. Still, they have to comprehend that DOACs are potent anticoagulants that may cause or contribute to bleeding. Challenges for the prescriber include decision pathways for choosing the right anticoagulant and dosage for a specific patient and to change bridging practice in case of invasive procedures. Laboratory personnel are challenged by DOAC due to limited 24/7 availability of specific DOAC quantification tests and by the impact of DOAC on routine coagulation assays and thrombophilia tests. Challenges for the emergency physician result from the increasing age of DOAC anticoagulated patients, the difficulties to establish last intake of DOAC type and dosage, to interpret coagulation test results in emergency situations, and to make decisions for or against DOAC reversal strategies in acute bleeding or urgent surgery. In conclusion, although DOACs make long-term anticoagulation safer and more convenient for patients, DOACs pose challenge to all healthcare providers involved in anticoagulation decisions. The key to correct patient management and optimal outcome therefore lies in education.

Intravenous Thrombolysis With Alteplase at 0.6 mg/kg in Patients With Ischemic Stroke Taking Direct Oral Anticoagulants

Background

We elucidated the safety of treatment with alteplase at 0.6 mg/kg within 24 hours for patients on direct oral anticoagulants (DOACs) before ischemic stroke onset.

Methods and Results

Consecutive patients with acute ischemic stroke who underwent intravenous thrombolysis using alteplase at 0.6 mg/kg from 2011 to 2021 were enrolled from our single‐center prospective stroke registry. We compared outcomes between patients taking DOACs and those not taking oral anticoagulants within 48 hours of stroke onset. The primary safety outcome was the rate of symptomatic intracranial hemorrhage with a ≥4‐point increase on the National Institutes of Health Stroke Scale score from baseline. The efficacy outcome was defined as 3‐month modified Rankin Scale score of 0 to 2 after stroke onset. Of 915 patients with acute ischemic stroke who received intravenous thrombolysis (358 women; median age, 76 years; median National Institutes of Health Stroke Scale score, 10), 40 patients took DOACs (6 took dabigatran, 8 took rivaroxaban, 16 took apixaban, and 10 took edoxaban) within 24 hours of onset and 753 patients did not take any oral anticoagulants. The rate of symptomatic intracranial hemorrhage was comparable between patients on DOACs and those not on oral anticoagulants (2.5% versus 2.4%, P=0.95). The rate of favorable outcomes was comparable between the 2 groups (59.4% versus 58.2%, P=0.46), although the admission National Institutes of Health Stroke Scale score was higher in patients on DOACs. No significant differences showed in any intracranial hemorrhage within 36 hours or mortality at 3 months.

Conclusions

Intravenous thrombolysis would be safely performed for patients on DOACs following the recommendations of the Japanese guidelines.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02251665.

Dabigatran in Cerebral Sinus Vein Thrombosis and Thrombophilia

Background and Purpose: Thrombophilic gene alterations are a major risk factor for cerebral sinus vein thrombosis (CSVT). Up to 30% of all patients with cerebral sinus vein thrombosis (CSVT) are found to have thrombophilic defects such as prothrombin mutation (PTM) or factor V Leiden (FVL). Their repercussions on the plasma levels of dabigatran etexilate are unclear. In this prospective case–control study, we aimed to investigate whether thrombophilia in CSVT has an influence on dabigatran peak-plasma levels. Methods: We monitored 10 patients over 12 months with acute CSVT, genetic thrombophilia with off-label use of dabigatran etexilate 150 mg twice a day and measured dabigatran peak-plasma levels and radiological outcome. We also monitored patients without genetic thrombophilia with dabigatran etexilate 150 mg twice a day and compared the efficiency and dabigatran peak-plasma levels. Results: Patients with homozygote PTM had significantly lower dabigatran peak concentration compared to patients with FVL or the control group (23 ± 4.2 vs. 152.3 ± 27.5 and 159.6 ± 63.08; p-value ≤ 0.05) There was no significant difference in dabigatran etexilate plasma levels between the heterozygote PTM group compared to patients with FVL or the control group (p = 0.29). There was no correlation between dabigatran peak concentration and delayed thrombus dissolution. Conclusions: Dabigatran peak concentration was stable in patients with heterozygote FVL and heterozygote PTM, but not in homozygote PTM, compared to controls. Genetic screening for thrombophilia in patients after CSVT may be useful to make patient tailored therapeutic decisions regarding oral anticoagulation and may decrease thrombotic events.