Clinical Course and Management of Patients with Emergency Surgery Treated with Direct Oral Anticoagulants or Vitamin K Antagonists-Results of the German Prospective RADOA-Registry

(1) Background: The clinical management of anticoagulated patients treated with direct oral anticoagulants (DOAC) or Vitamin K antagonists (VKA) needing emergency surgery is challenging. (2) Methods: The prospective German RADOA registry investigated treatment strategies in DOAC- or VKA-treated patients needing emergency surgery within 24 h after admission. Effectiveness was analysed by clinical endpoints including major bleeding. Primary observation endpoint was in hospital mortality until 30 days after admission. (3) Results: A total of 78 patients were included (DOAC: 44; VKA: 34). Median age was 76 years. Overall, 43% of the DOAC patients and 79% of the VKA patients were treated with prothrombin complex concentrates (PCC) (p = 0.002). Out of the DOAC patients, 30% received no hemostatic treatment compared to 3% (1/34) of the VKA patients (p = 0.002), and 7% of the DOAC patients and 21% of the VKA patients developed major or clinically relevant non-major bleeding at the surgical site (p = 0.093). In-hospital mortality was 13% with no significant difference between the two treatment groups (DOAC: 11%, VKA: 15%; p > 0.20). (4) Conclusions: The 30-day in-hospital mortality rate was comparable between both patient groups. VKA patients required significantly more hemostatic agents than DOAC patients in the peri- and postoperative surgery period.

Immature platelets in COVID-19

Platelets play a critical role in immune response. Coronavirus disease 2019 (COVID-19) patients with a severe course often show pathological coagulation parameters including thrombocytopenia, and at the same time the proportion of immature platelets increases. In this study, the platelet count and the immature platelet fraction (IPF) of hospitalized patients with different oxygenation requirements was investigated daily over a course of 40 days. In addition, the platelet function of COVID-19 patients was analyzed. It was found that the number of platelets in patients with the most severe course (intubation and extracorporeal membrane oxygenation (ECMO)) was significantly lower (111.5 ∙ 10⁶ /mL) than in the other groups (mild (no intubation, no ECMO): 203.5 ∙ 10⁶ /mL, p < .0001, moderate (intubation, no ECMO): 208.0 ∙ 10⁶ /mL, p < .0001). IPF tended to be elevated (10.9%). Platelet function was reduced. Differentiation by outcome revealed that the deceased patients had a highly significant lower platelet count and higher IPF (97.3 ∙ 10⁶ /mL, p < .0001, 12.2%, p = .0003).

[Basics for the Use of Andexanet]

BACKGROUND

 For life-threatening or uncontrollable bleeding in association with the thrombin inhibitor dabigatran, the monoclonal antibody fragment idarucizumab is available, and for bleeding in association with the direct factor Xa inhibitors rivaroxaban or apixaban, the modified recombinant FXa protein andexanet is available for reversal. These antidotes represent emergency drugs that are typically used only after performing guideline-compliant multimodal measures.

METHODS

 An interdisciplinary group of experienced experts in the fields of angiology, hematology, internal medicine, clinical pharmacology, laboratory medicine, transfusion medicine, anesthesiology, intensive care, and hemostaseology developed recommendations relevant to daily clinical practice based on the current scientific evidence.

RESULTS

 Reversal of oral anticoagulants should be considered for severe bleeding in the following situations: (1) life-threatening bleeding or refractory hemorrhagic shock, (2) intracerebral bleeding, or (3) endoscopically unstoppable gastrointestinal bleeding. After successful hemostasis, anticoagulation (e.g., direct oral anticoagulant, vitamin K antagonist, and heparin) should be resumed promptly, taking into account individual bleeding and thromboembolic risk.

DISCUSSION

 This article aims to facilitate the management of patients with andexanet by all medical disciplines involved, thereby ensuring optimal care of patients during bleeding episodes.

Changes in the Proteome of Platelets from Patients with Critical Progression of COVID-19

Platelets, the smallest cells in human blood, known for their role in primary hemostasis, are also able to interact with pathogens and play a crucial role in the immune response. In severe coronavirus disease 2019 (COVID-19) cases, platelets become overactivated, resulting in the release of granules, exacerbating inflammation and contributing to the cytokine storm. This study aims to further elucidate the role of platelets in COVID-19 progression and to identify predictive biomarkers for disease outcomes. A comparative proteome analysis of highly purified platelets from critically diseased COVID-19 patients with different outcomes (survivors and non-survivors) and age- and sex-matched controls was performed. Platelets from critically diseased COVID-19 patients exhibited significant changes in the levels of proteins associated with protein folding. In addition, a number of proteins with isomerase activity were found to be more highly abundant in patient samples, apparently exerting an influence on platelet activity via the non-genomic properties of the glucocorticoid receptor (GR) and the nuclear factor κ-light-chain-enhancer of activated B cells (NFκB). Moreover, carbonic anhydrase 1 (CA-1) was found to be a candidate biomarker in platelets, showing a significant increase in COVID-19 patients.

Pharmacokinetics of Phenprocoumon in Emergency Situations-Results of the Prospective Observational RADOA-Registry (Reversal Agent Use in Patients Treated with Direct Oral Anticoagulants or Vitamin K Antagonists Registry)

Background: Phenprocoumon has been used as an oral anticoagulant in patients with thromboembolic disease for more than 40 years. So far its pharmacokinetics have not been analyzed in emergency situations. Methods: Phenprocoumon-treated patients with major bleeding or urgent surgery were included in a prospective, observational registry. Phenprocoumon drug concentrations were analyzed in samples, collected as part of routine care using ultraperformance liquid chromatography tandem mass spectrometry. Moreover, anticoagulant intensity and drug half-life (t1/2) were calculated. Results: 115 patients were included. Phenprocoumon levels declined over time with a half-life of 5.27 and 5.29 days in patients with major bleedings (n = 82) and with urgent surgery (n = 33). Baseline phenprocoumon levels were 2.2 times higher in the bleeding group compared to the surgery group (1.92 vs. 0.87 ng/mL, p < 0.0001). International normalized ratio (INR) values decreased rapidly during the first 24 h. In 27.6% of patients a rebound of INR (recurrent increase > 1.5) was observed which was associated with significantly increased bleeding rates (22% vs. 4.2% in patients with or without INR rebound, p = 0.012). Conclusions: In emergency situations, the long half-life of phenprocoumon may cause INR rebound and associated recurrent bleedings. Optimal management may need to include repeated vitamin K supplementation over days.

The Human Myofibroblast Marker Xylosyltransferase-I: A New Indicator for Macrophage Polarization

Chronic inflammation and excessive synthesis of extracellular matrix components, such as proteoglycans (PG), by fibroblast- or macrophage-derived myofibroblasts are the hallmarks of fibrotic diseases, including systemic sclerosis (SSc). Human xylosyltransferase-I (XT-I), which is encoded by the gene XYLT1, is the key enzyme that is involved in PG biosynthesis. Increased cellular XYLT1 expression and serum XT-I activity were measured in SSc. Nothing is known so far about the regulation of XT-I in immune cells, and their contribution to the increase in measurable serum XT-I activity. We utilized an in vitro model, with primary human CD14+CD16+ monocyte-derived macrophages (MΦ), in order to investigate the role of macrophage polarization on XT-I regulation. The MΦ generated were polarized towards two macrophage phenotypes that were associated with SSc, which were classified as classical pro-inflammatory (M1-like), and alternative pro-fibrotic (M2-like) MΦ. The fully characterized M1- and M2-like MΦ cultures showed differential XT-I gene and protein expressions. The fibrotic M2-like MΦ cultures exhibited higher XT-I secretion, as well as increased expression of myofibroblast marker α-smooth muscle actin, indicating the onset of macrophage-to-myofibroblast transition (MMT). Thus, we identified XT-I as a novel macrophage polarization marker for in vitro generated M1- and M2-like MΦ subtypes, and broadened the view of XT-I as a myofibroblast marker in the process of MMT.

Humoral and cellular immune response levels at a 1-year follow-up after mild COVID-19

The primary objective of this study was to establish a 1-year follow-up of patients after mild COVID-19 with no or only short-term detection of antibodies shortly after disease. At 1 year after disease, cellular memory against SARS-CoV-2, as measured by IFN-γ release by T cells, was detected in 76% (38/50) of participants. The data suggest that even if antibody levels decline after the primary infection has resolved, a cellular immune response may be detectable for longer.

Intracranial bleeding under vitamin K antagonists or direct oral anticoagulants: results of the RADOA registry

Background and purpose

The use of direct oral anticoagulants (DOAC) has increased sharply and DOAC are the oral anticoagulant therapy (OAT) of choice for the majority of patients with newly-diagnosed atrial fibrillation. Intracranial hemorrhage is the most severe adverse event of OAT. Systematic data on the course of intracranial hemorrhage under DOAC compared to vitamin K antagonists (VKA) are warranted to enable shared decision making in AF patients needing OAT.

Methods

This is a secondary analysis of the patients with intracranial bleedings from the prospective multicenter emergency department-based RADOA registry, which collected data on patients admitted with major bleeding while taking VKA or DOAC. The primary endpoint was in-hospital mortality until day 30. We evaluated hematoma volume and short-term clinical outcomes in relation to the extent of active OAT according to coagulation parameters and OAT plasma levels measured by UPLC-MS/MS.

Results

Of 193 patients with major bleeding, 109 (56.5%) had intracranial hemorrhage [52.3% intracerebral (ICH), 33.9% subdural (SDH), 11.0% subarachnoidal (SAH)]. 64 (58.7%) were on VKA and 45 (41.2%) were on DOAC. On admission, we could confirm active anticoagulation in 97.7% of VKA-treated patients based on either INR > 1.3 or phenprocoumon levels and in 75.8% of DOAC-treated patients based on DOAC levels. Patients suffering an intracranial hemorrhage under VKA showed significantly larger hematoma volumes and a higher in-hospital mortality. Especially in intracerebral hemorrhage, we observed a higher initial severity and numerically greater proportion of early changes towards palliative therapy under VKA, which coincided with a numerically higher case fatality.

Conclusions

We show significantly smaller hematoma volumes for ICH and SDH under DOAC in comparison to VKA and a significantly lower 30-day in-hospital mortality rate of DOAC-ICH, even before the introduction of specific antidotes. These data strongly support the use of DOAC whenever possible in patients requiring OAT.

Trial Registration: http://www.clinicaltrials.gov; Unique identifier: NCT01722786.

Pharmacokinetics of Direct Oral Anticoagulants in Emergency Situations: Results of the Prospective Observational RADOA-Registry

BACKGROUND

Direct oral anticoagulants (DOACs) are increasingly used worldwide. Little is known so far about their pharmacokinetics in emergency situations.

METHODS

A prospective, observational registry was performed to determine the clinical course in consecutive patients with major bleeding or urgent surgery treated with DOACs. In samples collected as part of routine care DOAC drug concentrations were measured using ultraperformance liquid chromatography-tandem mass spectrometry. Anticoagulant intensity at first presentation and drug half-life (t _1/2), tested in repeat samples, were evaluated.

RESULTS

A total of 140 patients were prospectively included. Pharmacokinetic data were available in 94% (132/140) of patients. Note that 67% (89/132) experienced life-threatening bleeding and 33% (43/132) needed an urgent surgery. For pharmacokinetic analysis a total of 605 blood samples was available. Median concentration on admission was 205 ng/mL for rivaroxaban and 108 ng/mL for apixaban. All treatment groups showed a high variation of drug concentrations at baseline. In rivaroxaban-treated patients t _½ was 17.3 hours (95% confidence interval [CI]: 15.4-19.7) without significant difference in both groups (major bleeding: t _½ 16.7 hours, 95% CI: 14.7-19.3; urgent surgery: t _½ 19.7 hours, 95% CI: 15.2-27.9; p = 0.292). In apixaban-treated patients t _½ was 25.0 hours (95% CI: 22.9-27.6) with a longer t _½ after urgent surgery (t _1/2: 30.8 hours; 95% CI: 26.9-36.4) compared with severe bleeding (t _1/2: 20.8 hours; 95% CI: 18.8-23.2; p < 0.001).

CONCLUSION

Emergency patients under DOAC treatment show a high variation of anticoagulant concentrations at baseline. Compared with rivaroxaban, apixaban showed a lower median concentration on admission and a longer t _½.

Point-of-care testing of coagulation in patients treated with edoxaban

Edoxaban, alongside other direct oral anticoagulants (DOAC), is increasingly used for prevention of thromboembolism, including stroke. Despite DOAC therapy, however, annual stroke rate in patients with atrial fibrillation remains 1–2%. Rapid exclusion of relevant anticoagulation is necessary to guide thrombolysis or reversal therapy but, so far, no data exists on the effect of edoxaban on available point-of-care test systems (POCT). To complete our previous investigation on global coagulation-POCT for the detection of DOAC, we evaluated whether CoaguChek®-INR (CC-INR) is capable of safely ruling out edoxaban concentrations above the current treatment thresholds of 30/50 ng/mL in a blood sample. We studied patients receiving a first dose of edoxaban; excluding subjects receiving other anticoagulants. Six blood samples were collected from each patient: before drug intake, 0.5, 1, 2 and 8 h after intake, and at trough (24 h). CC-INR and mass spectrometry for edoxaban concentrations were performed for each time-point. One hundred and twenty blood samples from 20 patients contained 0–302 ng/mL of edoxaban. CC-INR ranged from 0.9 to 2.3. Pearson’s correlation coefficient showed strong correlation between CC-INR and edoxaban concentrations (r = 0.73, p < 0.001). Edoxaban concentrations > 30 and > 50 ng/mL were ruled out by CC-INR ≤ 1.0 and ≤ 1.1, respectively, with high specificity (> 95%), and a sensitivity of 44% (95%-confidence interval: 30–59%) and 86% (74–93%), respectively. Our study represents the first evaluation of coagulation-POCT in edoxaban-treated patients. CC-POCT is suitable to safely exclude clinically relevant edoxaban concentrations prior to thrombolysis, or guide reversal therapy in stroke patients.

Pharmacokinetics and Biologic Activity of Apixaban in Healthy Dogs

Thrombosis is common in critically ill dogs and causes considerable morbidity and mortality. The direct factor Xa inhibitor apixaban is safe, efficacious, and convenient in humans. This study aimed to determine the pharmacokinetics (PK), bioactivity, protein binding, and bioavailability of apixaban following intravenous (IV) and oral (PO) administration to healthy dogs. Six healthy, adult, mixed-breed dogs were administered apixaban 0.18 mg/kg IV and then following a minimum 2-week washout period administered apixaban 0.2 mg/kg PO. Dogs were monitored using an apixaban-calibrated anti-Xa bioassay, prothrombin time (PT) and activated partial thromboplastin time (aPTT) and tissue-factor thromboelastography (TF-TEG). Plasma apixaban concentrations were measured using liquid chromatography-tandem mass spectrometry. Concentration-time plots were constructed, and PK modeling performed using compartmental methods. Administration of IV and PO apixaban was well-tolerated. Following IV administration, mean half-life was 4.1 h, and volume of distribution was 177 ml/kg. Apixaban was highly protein bound (98.6%). Apixaban concentrations and anti-Xa activity were highly correlated (R2 0.994, P < 0.0001). Intravenous apixaban significantly prolonged PT at time points up to 1 h, and aPTT at time points up to 0.25 h post-administration. Coagulation times were positively correlated with apixaban concentrations (PT R2 0.599, P < 0.0001; aPTT R2 0.430, P < 0.0001) and TF-TEG R-time was significantly prolonged 0.25 h post-administration. Following oral administration, mean bioavailability was 28.4%, lag time was 2 h, time to Cmax was 5 h and the apparent elimination half-life was 3.1 h. Oral apixaban significantly prolonged PT at 4, 6, and 8 h but aPTT and TF-TEG were not consistently affected by oral apixaban. Apixaban concentrations are best monitored using anti-Xa activity. Future studies should determine PK and bioactivity of other doses using commercial tablets and following multidose administration and establish safe, effective dosing ranges in sick dogs.

Point-of-care testing for emergency assessment of coagulation in patients treated with direct oral anticoagulants including edoxaban

Background

Direct oral anticoagulants (DOAC) including edoxaban are increasingly used for stroke prevention in atrial fibrillation. Despite treatment, annual stroke rate in these patients remains 1–2%. Rapid assessment of coagulation would be useful to guide thrombolysis or reversal therapy in this growing population of DOAC/edoxaban-treated stroke patients. Employing the Hemochron™ Signature Elite point-of-care test system (HC-POCT), clinically relevant plasma concentrations of dabigatran and rivaroxaban can be excluded in a blood sample. However, no data exists on the effect of edoxaban on HC-POCT results.

We evaluated whether edoxaban plasma concentrations above the current treatment thresholds for thrombolysis or anticoagulation reversal (i.e., 30 and 50 ng/mL) can be ruled out with the HC-POCT.

Methods

We prospectively studied patients receiving a first dose of edoxaban. Six blood samples were collected from each patient: before, 0.5, 1, 2, 8, and 24 h after drug intake. HC-POCT-based INR (HC-INR), activated clotting time (HC-ACT+ and HC-ACT-LR), activated partial thromboplastin time (HC-aPTT), and mass spectrometry for edoxaban plasma concentrations were performed at each time-point. We calculated correlations, receiver operating characteristics (ROC) and test-specific cut-offs for ruling out edoxaban concentrations > 30 and > 50 ng/mL in a blood sample.

Results

One hundred twenty blood samples from 20 edoxaban-treated patients were analyzed. Edoxaban plasma concentrations ranged from 0 to 512 ng/mL. HC-INR/HC-ACT+/HC-ACT-LR/HC-aPTT ranged from 0.7–8.3/78–310 s/65–215 s/19–93 s, and Pearson’s correlation coefficients showed moderate to very strong correlations with edoxaban concentrations (r = 0.95/0.79/0.70/0.60). With areas under the ROC curve of 0.997 (95% confidence interval: 0.991–0.971) and 0.989 (0.975–1.000), HC-INR most reliably ruled out edoxaban concentrations > 30 and > 50 ng/mL, respectively, and HC-INR results ≤1.5 and ≤ 2.1 provided specificity/sensitivity of 98.6% (91.2–99.9)/98.0% (88.0–99.9) and 96.8% (88.0–99.4)/96.5% (86.8–99.4).

Conclusions

Our study represents the first systematic evaluation of the HC-POCT in edoxaban-treated patients. Applying sufficiently low assay-specific cut-offs, the HC-POCT may not only be used to reliably rule out dabigatran and rivaroxaban, but also very low edoxaban concentrations in a blood sample. Because the assay-specific cut-offs were retrospectively defined, further investigation is warranted.

Trial registration

ClinicalTrials.gov, registration number: NCT02825394, registered on: 07/07/2016, URL

Supplementary Information

The online version contains supplementary material available at 10.1186/s42466-021-00105-4.

Retrospective analysis of 426 donors of a convalescent collective after mild COVID-19

Background

The novel coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread across the world. The aim of our study was to characterize mild courses and to determine the antibody status for these patients.

Methods

We initiated an appeal for convalescent plasma donations. 615 people contacted us, and we ultimately included 426 in our analyses, in whom it was possible to assume COVID-19 based on detection of specific SARS-CoV-2 antibodies or virus detection during the disease using RT-PCR.

Results

The median duration of the disease was 12 days and the most common symptoms were fatigue, cough and olfactory and gustatory dysfunction. Anti-SARS-CoV-2 IgG was detected in 82.4% of the persons and IgA antibodies were found in 73.9%. In 10.8%, no antibodies were detectable despite a positive RT-PCR result during the disease. Nevertheless, of 24 persons with asymptomatic courses of COVID-19, antibodies against SARS-CoV-2 could be detected in 23 (96%). Furthermore, there was a correlation between the duration of the disease and the detection of IgG antibodies. In addition, a correlation between the determined IgG antibodies and neutralizing antibodies was shown.

Conclusion

In this study, we were able to describe mild COVID-19 courses and determine antibody statuses for them. It could be shown that, despite SARS-CoV-2 detection during the disease, not all individuals developed antibodies or their level of antibodies had dropped below the detection limit shortly after the end of the disease. The extent to which immunity to re-infection is given in persons with undetectable antibodies (IgG, IgA) needs to be investigated in future studies.

Specific Point-of-Care Testing of Coagulation in Patients Treated with Dabigatran

BACKGROUND AND PURPOSE

 Accurate and rapid assessment of coagulation status is necessary to guide thrombolysis or reversal of anticoagulation in stroke patients, but commercially available point-of-care (POC) assays are not suited for coagulation testing in patients treated with direct oral anticoagulants (DOACs). We aimed to evaluate the direct thrombin monitoring (DTM) test card by Helena Laboratories (Texas, United States) for anti-IIa-specific POC coagulation testing, hypothesizing that its POC-ecarin clotting time (POC-ECT) accurately reflects dabigatran plasma concentrations.

METHODS

 A prospective single-center diagnostic study (ClinicalTrials.gov-identifier: NCT02825394) was conducted enrolling patients receiving a first dose of dabigatran and patients already on dabigatran treatment. Blood samples were collected before drug intake and 0.5, 1, 2, 8, and 12 hours after intake. POC-ECT was performed using whole blood (WB), citrated blood (CB), and citrated plasma (CP). Dabigatran plasma concentrations were determined by mass spectrometry.

RESULTS

 In total, 240 blood samples from 40 patients contained 0 to 275 ng/mL of dabigatran. POC-ECT with WB/CB/CP ranged from 20 to 186/184/316 seconds. Pearson's correlation coefficient showed a strong correlation between dabigatran concentrations and POC-ECT with WB/CB/CP (R2  = 0.78/0.90/0.92). Dabigatran concentrations >30 and >50 ng/mL (thresholds for thrombolysis, surgery, and reversal therapy according to clinical guidelines) were detected by POC-ECT with WB/CB/CP (>36/35/45 and >43/45/59 seconds) with 95/97/97 and 96/98/97% sensitivity, and 81/87/94 and 74/60/91% specificity.

CONCLUSION

 This first study evaluating DOAC-specific POC coagulation testing revealed an excellent correlation of POC-ECT with actual dabigatran concentrations. Detecting clinically relevant dabigatran levels with high sensitivity/specificity, the DTM assay represents a suitable diagnostic tool in acute stroke, hemorrhage, and urgent surgery.

How would we treat our own heparin-induced thrombocytopenia during cardiac surgery?

The aim of this article is to provide a comprehensive review of the current state of knowledge on heparin-induced thrombocytopenia (HIT) in cardiac surgery. The management of HIT patients undergoing cardiac surgery with cardiopulmonary bypass is complex and requires an interdisciplinary and patient-tailored approach because available evidence is limited and current anticoagulation strategies have potential risks. An index case is used to discuss both the established and new perioperative therapeutic options in HIT patients undergoing urgent cardiac surgery with cardiopulmonary bypass.

Severe Hemorrhage Associated With Oral Anticoagulants

BACKGROUND

Few data have been published to date on outcomes after the common clinical experience of severe hemorrhage in orally anticoagulated patients.

METHODS

A prospective, multicenter observational study was carried out to investigate outcomes and management in a series of consecutive patients who sustained a severe hemorrhage under treatment with vitamin K antagonists (VKA) or direct oral anticoagulant drugs (DOAC). The primary endpoint was in-hospital death up to and including day 30 after hospital admission. The secondary endpoints were the duration of bleeding, in-hospital death due to hemorrhage (as defined by the study physician examining the patient's records), the use of antagonists, the extent of supportive measures used to stop the hemorrhage, and an assessment of causality. Consecutive patients were recruited until a predefined number of patients was reached in both groups.

RESULTS

Among 193 patients with severe hemorrhage, 97 had been taking a VKA, and 96 had been taking a DOAC. 13.0 % (95% confidence interval [8.6; 18.5]; 25/193) of the overall group patients died in the first 30 days after hospital admission, including 17.5% ([10.6; 26.6]; 17/97) in the VKA group and 8.3% ([3.7; 15.8]; 8/96) in the DOAC group (p = 0.085). The median duration of bleeding was 19.8 hours in the VKA group and 27.8 hours in the DOAC group (p = 0.632). The in-hospital mortality due to hemorrhage was higher in the VKA group than in the DOAC group (15.5% [15/97] versus 4.2% [4/97]; p = 0.014). Only the use of prothrombin complex concentrates (PCCs) lowered the median duration of hemorrhage in the two patient groups. In 35% (68/193) of the patients, the hemorrhage was caused by an external influence, most commonly a fall.

CONCLUSION

The in-hospital mortality was higher among patients treated with VKA than among patients treated with DOAC, although the difference failed to reach statistical significance.

Direct oral anticoagulants and cardiac surgery: A descriptive study of preoperative management and postoperative outcomes

OBJECTIVE

Recommendations for perioperative management of direct oral anticoagulant (DOAC) treatment in cardiac surgery are lacking. To establish a standardized approach for these patients, we compared hemorrhagic complications and clinical outcomes in patients on DOAC medication, patients on vitamin K antagonists (VKA), and patients without preoperative anticoagulation.

METHODS

All 3 groups underwent major cardiac surgery and were retrospectively analyzed: patients on DOAC were advised to take their last DOAC dose 4 days before hospital admission, and DOAC plasma levels were measured the day before surgery. In patients with plasma levels of >30 ng/mL, surgery was postponed until plasma level was below this threshold level. Postoperative chest tube drainage, bleeding complications, use of blood products, and thromboembolic events were collected for all groups.

RESULTS

A total of 5439 patients no anticoagulation, 239 patients on VKA, and 487 patients on DOAC medication were included between April 2014 and July 2017. Adjusted postoperative chest tube drainage did not differ between the DOAC and VKA groups for the strategy applied in this study (380 mL/12 hours vs 360 mL/12 hours). Moreover, secondary endpoint measures, such as rethoracotomy (30 [6.16%] vs 15 [6.28%]), 30-day-mortality 12 [2.46%] vs 7 [2.93%]), blood-product use, and stroke, were not significantly different through implementation of our standardized study management (P > .05).

CONCLUSIONS

Our standardized management for perioperative discontinuation of DOAC therapy may provide a safe approach to minimize hemorrhagic complications in cardiac surgery in patients on DOACs.

Limitations of Specific Coagulation Tests for Direct Oral Anticoagulants: A Critical Analysis

Background

During treatment with direct oral anticoagulants (DOAC), coagulation assessment is required before thrombolysis, surgery, and if anticoagulation reversal is evaluated. Limited data support the accuracy of DOAC‐specific coagulation assays around the current safe‐for‐treatment threshold of 30 ng/mL.

Methods and Results

In 481 samples obtained from 96 patients enrolled at a single center, DOAC concentrations were measured using Hemoclot direct thrombin inhibitor assay, Biophen direct thrombin inhibitor assay or ecarin clotting time for dabigatran, chromogenic anti‐Xa assay (AXA) for factor Xa inhibitors (rivaroxaban, apixaban) and ultraperformance liquid chromatography–tandem mass spectrometry as reference. All dabigatran‐specific assays had high sensitivity to concentrations >30 ng/mL, but specificity was lower for Hemoclot direct thrombin inhibitor assay (78.2%) than for Biophen direct thrombin inhibitor assay (98.9%) and ecarin clotting time (94.6%). AXA provided high sensitivity and specificity for rivaroxaban, but low sensitivity for apixaban (73.8%; concentrations up to 82 ng/mL were misclassified as <30 ng/mL). If no DOAC‐specific calibration for AXA is available, results 2‐fold above the upper limit of normal indicate relevant rivaroxaban concentrations. For apixaban, all elevated results should raise suspicion of relevant anticoagulation.

Conclusions

DOAC‐specific tests differ considerably in diagnostic performance for concentrations close to the currently accepted safe‐for‐treatment threshold. Compared with Biophen direct thrombin inhibitor assay and ecarin clotting time, limited specificity of Hemoclot direct thrombin inhibitor assay poses a high risk of unnecessary anticoagulation reversal or treatment delays in patients on dabigatran. While AXA accurately detected rivaroxaban, the impact of low apixaban levels on the assay was weak. Hence, AXA results need to be interpreted with extreme caution when used to assess hemostatic function in patients on apixaban.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov. Unique identifiers: NCT02371044, NCT02371070.

Pharmacokinetics and Pharmacodynamics of an Oral Formulation of Apixaban in Horses After Oral and Intravenous Administration

Horses with inflammatory and infectious disorders are often treated with injectable heparin anticoagulants to prevent thrombotic complications. In humans, a new class of direct oral acting anticoagulants (DOAC) appear as effective as heparin, while eliminating the need for daily injections. Our study in horses evaluated apixaban, a newly approved DOAC for human thromboprophylaxis targeting activated factor X (Xa). Our goals were to: (1) Determine pharmacokinetics and pharmacodynamics of apixaban after oral (PO) and intravenous (IV) administration in horses; (2) Detect any inhibitory effects of apixaban on ex vivo Equid herpesvirus type 1 (EHV-1)-induced platelet activation, and (3) Compare an anti-Xa bioactivity assay with ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) for measuring apixaban concentrations. In a blinded placebo-controlled cross-over study, five horses received a single dose (0.2 mg/kg) of apixaban or placebo PO or IV. Blood was collected before and at 3 (IV) or 15 (PO) min, 30 and 45 min, and 1, 2, 3, 4, 6, 8, and 24 h after dosing for measuring apixaban UPLC-MS concentrations and anti-Xa activity. Pharmacodynamic response was measured in a dilute prothrombin time (dPT) assay. Flow cytometric EHV-1-induced platelet P-selectin expression and clinical pathologic safety testing were performed at baseline, 2 and 24 h and baseline and 24 h, respectively. We found no detectable apixaban in plasma PO administration. After IV administration, plasma apixaban levels followed a two-compartment model, with concentrations peaking at 3 min and decreasing to undetectable levels by 8 h. The elimination half-life was 1.3 ± 0.2 h, with high protein binding (92–99%). The dPT showed no relationship to apixaban UPLC-MS concentration and apixaban did not inhibit EHV-1-induced platelet activation after IV dosing. Apixaban anti-Xa activity showed excellent correlation to UPLC-MS (r² = 0.9997). Our results demonstrate that apixaban has no apparent clinical utility as an anticoagulant for horses due to poor oral availability.

Effect of vitamin D on all-cause mortality in heart failure (EVITA): a 3-year randomized clinical trial with 4000 IU vitamin D daily

Aims

Circulating 25-hydroxyvitamin D (25OHD) levels <75 nmol/L are associated with a nonlinear increase in mortality risk. Such 25OHD levels are common in heart failure (HF). We therefore examined whether oral vitamin D supplementation reduces mortality in patients with advanced HF.

Methods and results

Four hundred HF patients with 25OHD levels <75 nmol/L were randomized to receive 4000 IU vitamin D daily or matching placebo for 3 years. Primary endpoint was all-cause mortality. Key secondary outcome measures included hospitalization, resuscitation, mechanical circulatory support (MCS) implant, high urgent listing for heart transplantation, heart transplantation, and hypercalcaemia. Initial 25OHD levels were on average <40 nmol/L, remained around 40 nmol/L in patients assigned to placebo and plateaued around 100 nmol/L in patients assigned to vitamin D. Mortality was not different in patients receiving vitamin D (19.6%; n = 39) or placebo (17.9%; n = 36) with a hazard ratio (HR) of 1.09 [95% confidence interval (CI): 0.69-1.71; P = 0.726]. The need for MCS implant was however greater in patients assigned to vitamin D (15.4%, n = 28) vs. placebo [9.0%, n = 15; HR: 1.96 (95% CI: 1.04-3.66); P = 0.031]. Other secondary clinical endpoints were similar between groups. The incidence of hypercalcaemia was 6.2% (n = 10) and 3.1% (n = 5) in patients receiving vitamin D or placebo (P = 0.192).

Conclusion

A daily vitamin D dose of 4000 IU did not reduce mortality in patients with advanced HF but was associated with a greater need for MCS implants. Data indicate caution regarding long-term supplementation with moderately high vitamin D doses.

Trial Registration Information

clinicaltrials.gov Idenitfier: NCT01326650.

Abstract 98: Point-of-care Testing of Coagulation in Patients Treated With the Non-vitamin K Antagonist Oral Anticoagulant Edoxaban

Introduction: Edoxaban, alongside other non-vitamin K antagonist oral anticoagulants (NOAC), is increasingly used for stroke prevention in patients with atrial fibrillation. Despite treatment, stroke rate in these patients remains one to two percent per year. In this growing population of edoxaban/NOAC-treated stroke patients, rapid assessment of coagulation would be useful to guide the decision for thrombolysis or reversal therapy in case of a neurovascular emergency. However, no data exists on the effect of edoxaban on available point-of-care test (POCT) systems.

Hypothesis: Test assays of the commercially available CoaguChek® (CC) and Hemochron® are able to detect clinically relevant concentrations of edoxaban in a blood sample.

Methods: We studied patients receiving their first dose of edoxaban. Subjects receiving other anticoagulants were excluded. Six blood samples were collected from each patient: before drug intake, 30 minutes, one, two, and eight hours after intake, as well as before the next dose. Coagulation-POCT and mass spectrometry for gold standard-determination of edoxaban plasma concentration were performed at each time point.

Results: 120 blood samples from 20 edoxaban-treated patients were analyzed. Edoxaban concentrations ranged from 0 to 302ng/mL. CC-INR ranged from 0.9 to 2.3. Pearson’s correlation coefficient showed a strong correlation between CC-INR and edoxaban concentrations (r=0.73). Edoxaban concentrations > 30ng/mL (threshold for thrombolysis according to the European Stroke Organisation) were detected by CC-INR ≥ 1.1 with 96% sensitivity and 44% specificity (89% sensitivity and 88% specificity for CC-INR ≥ 1.2; AUC=0.92).

Conclusions: Our study represents the first systematic evaluation of coagulation POCT in edoxaban-treated patients. Available coagulation POCT devices may be able to reliably detect clinically relevant edoxaban concentrations in blood samples of stroke patients in the emergency setting. In addition to edoxaban-POCT analyses, we will present further data on NOAC-specific POCT from our SPOCT-NOAC study.

Isolated transfusion of leucocyte-depleted apheresis platelet concentrates and outcomes after cardiac surgery

We investigated the association of isolated leucocyte-depleted single-donor apheresis platelet concentrate transfusion with short- and long-term outcomes of patients undergoing isolated or combined coronary artery bypass and valve surgery. Propensity score matching was used to compare the results of patients without blood product transfusion and patients with isolated platelet transfusion (n = 167 per group). The primary end-point was a composite of operative complications. Additionally, we assessed coronary reintervention and overall mortality over a follow-up period of 7.5 years. In the platelet- and platelet+ groups, the composite end-point was reached at 9.6% and 12.3%, respectively (P = 0.307). None of the patients died within 30 days. None of the patients needed coronary reintervention during follow-up. Long-term mortality was similar between groups (P > 0.05). Isolated leucocyte-depleted apheresis platelet transfusion does not appear to be associated with an increase in morbidity or mortality in non-complex cardiac surgery. However, larger studies are needed.

Diagnostic Accuracy of a Novel Chromogenic Direct Thrombin Inhibitor Assay: Clinical Experiences for Dabigatran Monitoring

Background Direct oral anticoagulants (DOACs) are increasingly replacing vitamin K antagonists (VKA) for clinical indications requiring long-term oral anticoagulation. In contrast to VKA, treatment with DOAC including dabigatran—the only direct thrombin inhibitor amongst them—does not require therapeutic drug monitoring. However, in case of treatment complications (e.g., major haemorrhage) and conditions requiring urgent surgery or thrombolytic therapy, information about actual DOAC plasma levels is needed to guide treatment decisions. Due to short reagent stability, limited accuracy at low dabigatran levels and high heparin sensitivity, the applicability of the widely used Hemoclot thrombin inhibitor (HTI) coagulation assay is limited in the emergency setting. Methods Dabigatran concentrations of 288 citrated plasma samples taken from 48 dabigatran-treated patients with drug concentrations of up to 300 ng/mL were measured with the chromogenic anti-IIa Biophen direct thrombin inhibitor (BDTI) assay and results compared with HTI using ultra performance liquid chromatography—tandem mass spectrometry as the reference method for measuring dabigatran plasma concentrations. Results BDTI results showed a very strong correlation with dabigatran concentrations (r = 0.965, p < 0.0001) as well as a low intra- and inter-assay variation of <5%. Compared with HTI, BDTI provides an improved on-board reagent stability of 72 hours, rapid turnaround times comparable to routine coagulation assays, high accuracy at low drug levels and reduced heparin sensitivity. Conclusion The BDTI is an ideal coagulation assay for the around-the-clock determination of dabigatran plasma levels in clinical routine including emergency situations.

Analysis of SAGE data in human platelets: Features of the transcriptome in an anucleate cell

A comprehensive SAGE (serial analysis of gene expression) library of purified human platelets was established. Twenty-five thousand (25,000) tags were sequenced, and after removal of mitochondrial tags, 12,609 (51%) non-mitochondrial-derived tags remained, corresponding to 2,300 different transcripts with expression levels of up to 30,000 tags per million. This new, highly purified SAGE library of platelets is enriched in specific transcripts.The complexity in terms of tag distribution is similar to cells that are still able to replenish their mRNA pool by transcription.We show that our SAGE data are consistent with recently published microarray data but show further details of the platelet transcriptome, including (i) longer UTR regions and more stable folding in the enriched mRNAs, (ii) biologically interesting new candidate mRNAs that show regulatory elements, including elements for RNA stabilization or for translational control, and (iii) significant enrichment of specific, highly transcribed mRNAs compared to a battery of SAGE libraries from other tissues. Among several regulatory mRNA elements known to be involved in mRNA localization and translational control, CPE elements are in particular enriched in the platelet transcriptome. mRNAs previously reported to be translationally regulated were found to be present in the library and were validated by real-time PCR. Furthermore, specific molecular functions such as signal transduction activity were found to be significantly enriched in the platelet transcriptome.These findings emphasize the richness and diversity of the platelet transcriptome.

ADAMTS13 activity is decreased in a septic porcine model

During sepsis, the balance between abundantly secreted von Wille-brand factor (VWF) and the activity of its size regulating protease ADAMTS13 is assumed to be involved in coagulation abnormalities. We aimed to establish a porcine model with haemorrhagic shock with consecutive sepsis and hypothesised that a decreased ADAMTS13-activity as well as an altered VWF multimer pattern is associated with renal failure. Animals (n=21) were subjected to haemorrhagic shock. After volume replacement, intraperitoneal Escherichia coli sepsis was induced. Blood samples were drawn at baseline, after haemorrhage and sepsis induction. Directly postmortem we examined renal tissue by JONES-silver, CD61, VWF and fibrin staining for characterisation of thrombi. Renal failure was analysed by scoring PAS-stained sections for acute tubular damage. Glomerular microthrombi were observed in six of 21 septic animals. Porcine ADAMTS13 activity declined significantly during sepsis, accompanied by a drop-off in platelet count. At 12 hours after sepsis induction, ADAMTS13 activity was significantly diminished compared to sham controls, and an elevated acute tubular damage score was associated with an increased proportion of high-molecular-weight VWF multimers. Compared to baseline the proportion of high-molecular-weight VWF multimers increased significantly in septic animals. Similar to human sepsis, diminished ADAMTS13 activity was observed in a septic porcine model associated with a shift to rather thrombogenic VWF multimers and deposition of microthrombi. Therefore, this porcine model seems to be appropriate for performing functional and therapeutic studies in sepsis-associated ADAMTS13 deficiency.

Strain-dependent interactions of Streptococcus gallolyticus subsp. gallolyticus with human blood cells

BACKGROUND

Streptococcus gallolyticus subsp. gallolyticus (S. gallolyticus) is the causative pathogen in up to 20% of streptococcal-induced infective endocarditis (IE) cases. However, the underlying mechanisms of pathogenesis in S. gallolyticus have not yet been solved. Pathogens causing IE need to employ virulent strategies to initiate and establish infections, such as escape the bloodstream, invade the host-cell, and persist intracellularly. In this study, we examined the induction of inflammation by different S. gallolyticus strains in relation to their survival in whole blood and cell culture models as well as their ability to induce platelet aggregation. Phagocytosis of these bacteria by macrophages, followed by intracellular survival, was also quantified.

METHODS

In whole blood and THP-1 cell culture assays bacterial growth kinetics was determined by plating, followed by colony counting. Induction of interleukin (IL)-6 expression in whole blood of three healthy volunteers, caused by different strains, was quantified by ELISA. Gene expression of cytokines (IL1B, IL6 and IL8) was quantified by real-time PCR after stimulating THP-1 monocytes with bacteria. Induction of platelet aggregation was analyzed by light transmission aggregometry using the BORN method. A macrophage model was used to analyze phagocytosis of strains and their survival in macrophages within 48 h.

RESULTS

Strains promoted IL-6 secretion in a time-dependent fashion. For example, DSM16831 induced IL-6 secretion in whole blood earlier than other isolates, and was eliminated in the whole blood of one volunteer, whereas UCN34 could grow. Platelet aggregation depended on the different isolates used and on the individual platelet donor. Two strains (AC1181 and 010672/01) induced cytokine gene expression in THP-1 monocytes only marginally, compared to other strains. The phagocytosis rate of S. gallolyticus isolates differed significantly, and the isolates UCN34 and BAA-2069 could persist for a considerable time in the phagocytes.

CONCLUSION

The strain-dependent differences of S. gallolyticus isolates, observed during interaction with human blood cells, support the hypotheses that divergences in individual virulence factors determine a distinct pathogenicity of the isolates. These data constitute an additional step towards the elucidation of mechanisms in the complex, multifactorial pathogenesis of this IE pathogen.

Direct oral anticoagulants and heparins: laboratory values and pitfalls in 'bridging therapy'

Objectives

The three direct oral anticoagulants (DOACs) dabigatran, apixaban and rivaroxaban are now widely used in clinical practice. For patients requiring perioperative interruption of DOACs, heparin bridging is still under discussion. Here we show, for the first time, the influence of concomitantly used DOACs and heparins on laboratory assays.

Methods

For spiking experiments, 10 healthy donors and nine patients treated with DOACs were investigated. The measurement of DOACs and heparins was performed with routine methods on the ACL TOP [HEMOCLOT ® direct thrombin inhibitor (CoaChrom Diagnostica, Austria), COAMATIC ® Heparin (Chromogenix, USA) calibrated with rivaroxaban, apixaban, unfractionated heparin (UFH) and low molecular weight heparin (LMWH), additionally PT reagent RecombiPlasTin 2G and aPTT reagent SynthASil (Instrumentation Laboratory, Germany)] and the DOACs were additionally quantified with liquid chromatography-mass spectrometry. A linear regression model has been used to estimate the effect of DOAC prestimulation.

Results

No influence of dabigatran could be demonstrated in the anti-Xa testing methods for LMWH, UFH, rivaroxaban or apixaban. All FXa-inhibiting drugs affected all the anti-Xa testing methods in their own specific ways. Compared with heparin alone, measurement of heparins in samples with a basic concentration of DOACs (200 ng/ml) displays a more dramatic increase. Samples of patients with therapeutic intake of DOACs spiked with UFH and LMWH showed the expected pharmacokinetic profiles, but increased pharmacodynamic effects.

Conclusions

Direct thrombin and FXa inhibitors exhibit distinct effects on assay results when used concomitantly with heparins. These interactions must be considered in the interpretation of assay results during bridging therapy.

Abstract 20: Specific Point-of-care Testing of Coagulation in Patients Treated with Non-vitamin K Antagonist Oral Anticoagulants Part I (SPOCT-NOAC I)

Introduction: Non-vitamin K antagonist oral anticoagulants (NOAC) are increasingly replacing vitamin K antagonists for prevention of thromboembolism in atrial fibrillation (AF). Despite treatment, stroke rate in NOAC-treated AF-patients remains 1-2% per year. Subsequently, stroke physicians face a growing number of NOAC-treated patients with acute stroke. Rapid assessment of coagulation in NOAC-treated patients is vital prior to thrombolysis or reversal therapy, but existing point-of-care testing (POCT) is suboptimal. For the first time we evaluate NOAC-specific POCT.

Hypothesis: Ecarin clotting time (ECT)- and anti-Xa activity (ENOX)-POCT predict plasma concentrations of dabigatran and apixaban/edoxaban/rivaroxaban.

Methods: 80 patients receiving first NOAC-dose and 80 already on NOAC-treatment are enrolled in the SPOCT-NOAC I trial (N=40 for each NOAC). Subjects receiving other anticoagulants are excluded. Six blood samples are collected from each patient: before drug intake, 30min, 1, 2, and 8h after intake, and before next dose. NOAC-concentrations are measured by mass spectrometry.

Results: 240 blood samples of 40 dabigatran-treated patients were analyzed. Dabigatran-concentrations ranged from 0-274ng/mL. ECT-POCT ranged from 20-196s. Pearson’s correlation coefficient showed strong correlation between ECT-POCT and dabigatran-concentrations (r=0.87). Performance was improved through the use of citrated in place of non-citrated whole blood (r=0.93). Dabigatran-concentrations >50ng/mL (threshold for thrombolysis according to expert recommendation) were detected by ECT-POCT >50s with 98% sensitivity and 79% specificity. Baseline-samples not containing any dabigatran yielded normal ECT values.

Conclusions: This is the first study evaluating NOAC-specific POCT. Final results in the dabigatran group of SPOCT-NOAC show excellent correlation between ECT-POCT and dabigatran plasma concentrations; performance of ECT-POCT is even increased through the use of citrated whole blood. Relevant dabigatran-concentrations are detected with excellent sensitivity and specificity. In addition to ECT-POCT, we will present data on ENOX-POCT from apixaban-, edoxaban- and rivaroxaban-treated patients.

The Sysmex CS-5100 coagulation analyzer offers comparable analytical performance and excellent throughput capabilities

Objectives

This study compared the new high-volume blood coagulation analyzer Sysmex CS-5100 System™ (Siemens Healthcare Diagnostics, Erlangen, Germany) to the mid-volume blood coagulation analyzer Sysmex CS-2000i System™ (Siemens) for analytical performance. Additionally, the operational performance of the Sysmex CS-5100 System was compared with the blood coagulation analyzer ACL TOP 700 (Instrumentation Laboratory, Werfen Group, Kirchheim bei Munchen, Germany).

Materials and methods

We compared the Sysmex CS-5100 to the Sysmex CS-2000i and the ACL TOP analyzer for routine coagulation, chromogenic and immunological assays. Imprecision studies were performed for the Sysmex CS-5100 and Sysmex CS-2000i systems. A throughput and STAT analysis comparison of the CS-5100 and the ACL TOP was performed. A stress test was performed to characterize the robustness and the error rate of the CS-5100. We also performed correlation analysis between the CS-5100 and the CS-2000i or the ACL TOP in the measurement of patients’ samples.

Results

The inter-assay precision using the CS systems was impressive (inter-assay CV generally <3.5%) and the correlation between the two Sysmex analyzers was excellent. In the throughput study, the CS-5100 completed the measurement of 100 samples (210 results) in less than 49 min.

Conclusions

Our results demonstrated that the CS-5100 is a robust high-throughput analyzer, well-suited for coagulation laboratories.

•

We show a comparison between the CS-5100, CS-2000i and ACL TOP 700.

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CS-5100 is a high-volume coagulation analyzer with excellent inter-assay precision.

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The system has a considerable high throughput and a good software usability.

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The software was simple, intuitive to use and offers various monitoring possibilities.

Safety of Factor XIII Concentrate: Analysis of More than 20 Years of Pharmacovigilance Data

BACKGROUND

Plasma-derived factor XIII (FXIII) concentrate is an effective treatment for FXIII deficiency. We describe adverse drug reactions (ADRs) reported during pharmacovigilance monitoring of Fibrogammin®/Corifact® and review published safety data.

METHODS

Postmarketing safety reports recorded by CSL Behring from June 1993 to September 2013 were analyzed. Clinical studies published during the same period were also reviewed.

RESULTS

Commercial data indicated that 1,653,450,333 IU FXIII concentrate were distributed over the review period, equivalent to 1,181,036 doses for a 70 kg patient. 75 cases were reported (one/15,700 standard doses or 22,046,000 IU). Reports of special interest included 12 cases of possible hypersensitivity reactions (one/98,400 doses or 137,787,500 IU), 7 with possible thromboembolic events (one/168,700 doses or 236,207,200 IU), 5 of possible inhibitor development (one/236,200 doses or 330,690,100 IU), and 20 of possible pathogen transmission (one/59,100 doses or 82,672,500 IU). 19 pathogen transmission cases involved viral infection; 4 could not be analyzed due to insufficient data, but for all others a causal relationship to the product was assessed as unlikely. A review of published literature revealed a similar safety profile.

CONCLUSION

Assessment of ADRs demonstrated that FXIII concentrate carries a low risk of ADRs across various clinical situations, suggesting a favorable safety profile.

Donor-Derived Cell-Free DNA Is a Novel Universal Biomarker for Allograft Rejection in Solid Organ Transplantation

BACKGROUND

In solid organ transplantation, sensitive real-time biomarkers to assess the graft health are desirable to enable early intervention, for example, to avoid full-blown rejections. During rejection, high amounts of graft-derived cell-free DNA (GcfDNA) are shed into the blood stream. The quantification of this GcfDNA in allotransplantation is considered to fulfill this need, because it can be measured with great precision and at reasonable cost.

PATIENTS AND METHODS

Patients from 2 ongoing studies in kidney (KTx) and heart (HTx) transplantation were monitored blinded on a scheduled basis, by means of a published universal droplet digital polymerase chain reaction to quantify the GcfDNA.

RESULTS

Immediately after engraftment, GcfDNA reaches high values (>5% of total cfDNA), with a rapid decrease to values of <0.5% within 1 week. Living-related KTx recipients show lower initial values, reflecting the absence of preservation injury. Episodes of rejection in KTx and HTx are accompanied by a significant increase of GcfDNA (>5-fold) above values in patients without complications, occurring earlier than clinical or biochemical hints to rejection. One case of rejection, which became clinically suspect after 1 year and was proven with biopsy, showed a significant 10-fold increase 3 months earlier.

CONCLUSIONS

The quantification of GcfDNA has the potential to detect rejection episodes at early stages, when other means of diagnosis are not effective. The method's noninvasiveness enables the monitoring recipients at intervals that are desired to catch rejections at early actionable stages to prevent full-blown rejection. This biomarker will be particularly valuable in regimens to minimize immunosuppression.

Abstract 164: Specific Point-of-Care Testing of Coagulation in Patients Treated With Non-Vitamin K Antagonist Oral Anticoagulants Part I (SPOCT-NOAC I)

Introduction: Non-vitamin K antagonist oral anticoagulants (NOAC) are increasingly replacing vitamin K antagonists for prevention of thromboembolism in atrial fibrillation (AF) and venous thrombosis. Ischemic stroke rate in NOAC-treated AF-patients is 1-2% per year. Subsequently, stroke physicians face a growing number of NOAC-treated patients with acute stroke. Rapid assessment of coagulation in NOAC-treated patients is vital prior to thrombolysis, but existing point-of-care testing (POCT) is suboptimal. For the first time we evaluate NOAC-specific POCT.

Hypothesis: Ecarin clotting time (ECT)- and anti-Xa activity-POCT accurately predict plasma concentrations of dabigatran and apixaban/edoxaban/rivaroxaban.

Methods: 80 patients receiving first NOAC-dose and 80 already on NOAC-treatment will be enrolled (N=40 for each NOAC). Subjects receiving other anticoagulants will be excluded. 6 blood samples will be collected from each patient: before drug intake, 30min, 1, 2, and 8h after intake, and before next dose. NOAC-concentrations will be measured by mass spectrometry.

Results (preliminary): Until now 138 blood samples of 23 dabigatran-treated patients were analyzed. Dabigatran-concentrations ranged from 0-371ng/mL. ECT-POCT ranged from 20-219s. Pearson’s correlation coefficient showed strong correlation for ECT-POCT and dabigatran-concentrations (r=0.94, p<0.001). Dabigatran-concentrations >50ng/mL (threshold for thrombolysis according to expert recommendation) were detected by ECT-POCT (>50s) with 100% sensitivity and 82% specificity. Baseline-samples not containing any dabigatran yielded normal ECT-POCT.

Conclusions: This is the first study evaluating NOAC-specific POCT. Preliminary results show excellent correlation for ECT-POCT and dabigatran; relevant dabigatran-concentrations were detected in 100%. More pioneering results on NOAC-specific POCT will be presented.

UPLC-MRM Mass Spectrometry Method for Measurement of the Coagulation Inhibitors Dabigatran and Rivaroxaban in Human Plasma and Its Comparison with Functional Assays

Introduction

The fast, precise, and accurate measurement of the new generation of oral anticoagulants such as dabigatran and rivaroxaban in patients’ plasma my provide important information in different clinical circumstances such as in the case of suspicion of overdose, when patients switch from existing oral anticoagulant, in patients with hepatic or renal impairment, by concomitant use of interaction drugs, or to assess anticoagulant concentration in patients’ blood before major surgery.

Methods

Here, we describe a quick and precise method to measure the coagulation inhibitors dabigatran and rivaroxaban using ultra-performance liquid chromatography electrospray ionization-tandem mass spectrometry in multiple reactions monitoring (MRM) mode (UPLC-MRM MS). Internal standards (ISs) were added to the sample and after protein precipitation; the sample was separated on a reverse phase column. After ionization of the analytes the ions were detected using electrospray ionization-tandem mass spectrometry. Run time was 2.5 minutes per injection. Ion suppression was characterized by means of post-column infusion.

Results

The calibration curves of dabigatran and rivaroxaban were linear over the working range between 0.8 and 800 μg/L (r >0.99). Limits of detection (LOD) in the plasma matrix were 0.21 μg/L for dabigatran and 0.34 μg/L for rivaroxaban, and lower limits of quantification (LLOQ) in the plasma matrix were 0.46 μg/L for dabigatran and 0.54 μg/L for rivaroxaban. The intraassay coefficients of variation (CVs) for dabigatran and rivaroxaban were < 4% and 6%; respectively, the interassay CVs were < 6% for dabigatran and < 9% for rivaroxaban. Inaccuracy was < 5% for both substances. The mean recovery was 104.5% (range 83.8–113.0%) for dabigatran and 87.0% (range 73.6–105.4%) for rivaroxaban. No significant ion suppressions were detected at the elution times of dabigatran or rivaroxaban. Both coagulation inhibitors were stable in citrate plasma at -20°C, 4°C and even at RT for at least one week. A method comparison between our UPLC-MRM MS method, the commercially available automated Direct Thrombin Inhibitor assay (DTI assay) for dabigatran measurement from CoaChrom Diagnostica, as well as the automated anti-Xa assay for rivaroxaban measurement from Chromogenix both performed by ACL-TOP showed a high degree of correlation. However, UPLC-MRM MS measurement of dabigatran and rivaroxaban has a much better selectivity than classical functional assays measuring activities of various coagulation factors which are susceptible to interference by other coagulant drugs.

Conclusions

Overall, we developed and validated a sensitive and specific UPLC-MRM MS assay for the quick and specific measurement of dabigatran and rivaroxaban in human plasma.

Effect of Vitamin D or Activated Vitamin D on Circulating 1,25-Dihydroxyvitamin D Concentrations: A Systematic Review and Metaanalysis of Randomized Controlled Trials

BACKGROUND

Evidence is accumulating that circulating 1,25-dihydroxyvitamin D [1,25(OH)2D] concentrations are inversely related to overall mortality.

METHODS

We searched PubMed, Embase and ISI Web of Science for randomized controlled trials with a control group receiving a placebo instead of vitamin D/activated vitamin D and performed a metaanalysis to evaluate the effect of oral vitamin D/activated vitamin D on circulating 1,25(OH)2D concentrations using a random effects model.

RESULTS

We included 52 vitamin D intervention groups (4796 individuals) and 14 intervention groups with activated vitamin D (668 individuals). Vitamin D supplements increased circulating 1,25(OH)2D by 12.2 pmol/L (95% CI, 7.8-16.5 pmol/L) and 18.8 pmol/L (95% CI, 9.2-28.4 pmol/L) if only studies with a low risk of bias in study design and reporting were considered (n = 18). There was significant heterogeneity among studies (Cohran's Q P < 0.001, I(2) = 91%). The incremental effect was larger in studies using vitamin D alone compared with coadministration of calcium supplements (18.6 pmol/L; 95% CI, 12.7-24.4 pmol/L vs 4.9 pmol/L; 95% CI, -0.4 to 10.2 pmol/L; P = 0.001), and if quantification was performed with RIA vs other methods (17.1 pmol/L; 95% CI, 11.1-23.1 pmol/L vs 6.9 pmol/L; 95% CI, 1.0-12.8 pmol/L; P = 0.02). Activated vitamin D increased the mean circulating 1,25(OH)2D by 20.5 pmol/L (95% CI, 8.3-32.7 pmol/L; P = 0.04). Again, there was evidence for significant heterogeneity among studies (Cochran Q = 85.4; P < 0.001; I(2) = 87%), but subgroup analysis did not identify parameters significantly influencing the increment in 1,25(OH)2D concentrations.

CONCLUSIONS

Both vitamin D and activated vitamin D significantly increase circulating 1,25(OH)2D concentrations, but in vitamin D users this increase is suppressed by calcium coadministration.

Point-of-Care Testing of Coagulation in Patients Treated With Non-Vitamin K Antagonist Oral Anticoagulants

BACKGROUND AND PURPOSE

Specific coagulation assays for non-vitamin K antagonist oral anticoagulants (NOAC) are relatively slow and often lack availability. Although specific point-of-care tests (POCT) are currently not available, NOAC are known to affect established coagulation POCT. This study aimed at determining the diagnostic accuracy of the CoaguChek POCT to rule out relevant concentrations of rivaroxaban, apixaban, and dabigatran in real-life patients.

METHODS

We consecutively enrolled 60 ischemic stroke patients newly started on NOAC treatment and obtained blood samples at 6 prespecified time points. Samples were tested using the CoaguChek POCT, laboratory-based coagulation assays (prothrombin time and activated partial thromboplastin time, anti-Xa test and Hemoclot), and liquid chromatography-tandem mass spectrometry for direct determination of NOAC concentrations.

RESULTS

Three hundred fifty-six blood samples were collected. The CoaguChek POCT strongly correlated (r=0.82 P<0.001) with rivaroxaban concentrations but did not accurately detect dabigatran or apixaban. If used to estimate the presence of low rivaroxaban concentrations, POCT was superior to predictions based on normal prothrombin time and activated partial thromboplastin time values even if sensitive reagents were used. POCT-results≤1.0 predicted rivaroxaban concentrations<32 and <100 ng/mL with a specificity of 90% and 96%, respectively.

CONCLUSIONS

If anti-Xa test is not available, we propose the use of the CoaguChek POCT to guide thrombolysis decisions after individual risk assessment in rivaroxaban-treated patients having acute ischemic stroke.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02371044.

Addition of in-vitro generated endothelial microparticles to von-Willebrand plasma improves primary and secondary hemostasis

Increased endothelial microparticles (EMP) as markers for endothelial activation have been associated with worse outcomes in clinical prothrombotic situations. The procoagulant properties of EMP can be attributed to the expression of phospholipids, tissue factor and von-Willebrand factor on their surface. We therefore investigated whether addition of in-vitro generated EMP modifies hemostasis in plasma from patients with severe von-Willebrand disease (VWD). A large EMP pool was obtained from stimulated endothelial cell lines and EMP concentration was quantified by flow cytometry. The influence of EMP on primary and secondary hemostasis in VWD plasma was assessed using ristocetin-induced platelet aggregation (RIPA) and thrombin generation in a calibrated automated thrombogram (CAT), respectively. After addition of EMP, there was a significant increase in the maximal aggregation level in RIPA as well as a significant shortening of lag time and time-to-peak in CAT in comparison to control buffer. In summary, in vitro-generated EMP have the potential to improve hemostasis in severe VWD plasma and these results warrant further clinical reseach regarding their contribution to the clinical bleeding phenotype as well as their potential to improve replacement therapy.

Non-transient "self-sustaining" heparin-induced thrombocytopenia: 4-year persistence of a platelet-activating PF4/heparin-antibody status without heparin exposure

The more we come to understand the pathophysiology of heparin-induced thrombocytopenia (HIT) syndrome, the more we realize that HIT is a rather unusual immune response. One peculiar feature of HIT is the transient character of the antibodies. After cessation of exposure to heparins, the antibodies tend to disappear after 40-100 days. If re-immunization occurs, it generally takes at least 4 days to redevelop antibodies (if they are formed at all). We report about a patient who most likely developed platelet-activating IgG-specific platelet factor 4 (PF4)/heparin antibodies after knee surgery, experienced a transient ischemic attack years later [when HIT was diagnosed by using PF4/heparin ELISA] and presented a high number of these antibodies even 4 years after this first diagnosis of HIT without further re-exposure to heparin.

Pharmacokinetics and safety of a novel recombinant human von Willebrand factor manufactured with a plasma-free method: a prospective clinical trial

Safety and pharmacokinetics (PK) of recombinant von Willebrand factor (rVWF) combined at a fixed ratio with recombinant factor VIII (rFVIII) were investigated in 32 subjects with type 3 or severe type 1 von Willebrand disease (VWD) in a prospective phase 1, multicenter, randomized clinical trial. rVWF was well tolerated and no thrombotic events, inhibitors, or serious adverse events were observed. The PK of rVWF ristocetin cofactor activity, VWF antigen, and collagen-binding activity were similar to those of the comparator plasma-derived (pd) VWF-pdFVIII. In vivo cleavage of ultra-large molecular-weight rVWF multimers by ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13; the endogenous VWF protease) and generation of characteristic satellite bands were demonstrated. In 2 subjects with specific nonneutralizing anti-VWF-binding antibodies already detectable before rVWF infusion, a reduction in VWF multimers and VWF activity was observed. Stabilization of endogenous FVIII was enhanced following post-rVWF-rFVIII infusion as shown by the difference in area under the plasma concentration curve compared with pdVWF-pdFVIII (AUC0-∞) (P < .01). These data support the concept of administering rVWF alone once a therapeutic level of endogenous FVIII is achieved.