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.

Anti-PF4 immunothrombosis without proximate heparin or adenovirus vector vaccine exposure

ABSTRACT

Platelet-activating anti-platelet factor 4 (PF4)/heparin antibodies and anti-PF4 antibodies cause heparin-induced thrombocytopenia (HIT) and vaccine-induced immune thrombocytopenia and thrombosis (VITT), respectively. Diagnostic and treatment considerations differ somewhat between HIT and VITT. We identified patients with thrombocytopenia and thrombosis without proximate heparin exposure or adenovirus-based vaccination who tested strongly positive by PF4/polyanion enzyme-immunoassays and negative/weakly positive by heparin-induced platelet activation (HIPA) test but strongly positive by PF4-induced platelet activation (PIPA) test (ie, VITT-like profile). We tested these patients by a standard chemiluminescence assay that detects anti-PF4/heparin antibodies found in HIT (HemosIL AcuStar HIT-IgG(PF4-H)) as well as a novel chemiluminescence assay for anti-PF4 antibodies found in VITT. Representative control sera included an exploratory anti-PF4 antibody-positive but HIPA-negative/weak cohort obtained before 2020 (n = 188). We identified 9 patients with a clinical-pathological profile of a VITT-like disorder in the absence of proximate heparin or vaccination, with a high frequency of stroke (arterial, n = 3; cerebral venous sinus thrombosis, n = 4), thrombocytopenia (median platelet count nadir, 49 × 109/L), and hypercoagulability (greatly elevated D-dimer levels). VITT-like serological features included strong reactivity by PIPA (aggregation <10 minutes in 9/9 sera) and positive testing in the novel anti-PF4 chemiluminescence assay (3/9 also tested positive in the anti-PF4/heparin chemiluminescence assay). Our exploratory cohort identified 13 additional patient sera obtained before 2020 with VITT-like anti-PF4 antibodies. Platelet-activating VITT-like anti-PF4 antibodies should be considered in patients with thrombocytopenia, thrombosis, and very high D-dimer levels, even without a proximate exposure to heparin or adenovirus vector vaccines.

Long-term outcome in vaccine-induced immune thrombocytopenia and thrombosis

BACKGROUND

Rapid diagnosis and treatment has improved outcome of patients with vaccine-induced immune thrombocytopenia and thrombosis (VITT). However, after the acute episode, many questions on long-term management of VITT remained unanswered.

OBJECTIVES

To analyze, in patients with VITT, the long-term course of anti-platelet factor 4 (PF4) antibodies; clinical outcomes, including risk of recurrent thrombosis and/or thrombocytopenia; and the effects of new vaccinations.

METHODS

71 patients with serologically confirmed VITT in Germany were enrolled into a prospective longitudinal study and followed for a mean of 79 weeks from March 2021 to January 2023. The course of anti-PF4 antibodies was analyzed by consecutive anti-PF4/heparin immunoglobulin G enzyme-linked immunosorbent assay and PF4-enhanced platelet activation assay.

RESULTS

Platelet-activating anti-PF4 antibodies became undetectable in 62 of 71 patients (87.3%; 95% CI, 77.6%-93.2%). In 6 patients (8.5%), platelet-activating anti-PF4 antibodies persisted for >18 months. Five of 71 patients (7.0%) showed recurrent episodes of thrombocytopenia and/or thrombosis; in 4 of them (80.0%), alternative explanations beside VITT were present. After further COVID-19 vaccination with a messenger RNA vaccine, no reactivation of platelet-activating anti-PF4 antibodies or new thrombosis was observed. No adverse events occurred in our patients subsequently vaccinated against influenza, tick-borne encephalitis, varicella, tetanus, diphtheria, pertussis, and polio. No new thrombosis occurred in the 24 patients (33.8%) who developed symptomatic SARS-CoV-2 infection following recovery from acute VITT.

CONCLUSION

Once the acute episode of VITT has passed, patients appear to be at low risk for recurrent thrombosis and/or thrombocytopenia.

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.

Bleeding Issues in Women Under Oral Anticoagulation

In premenopausal women treatment with direct oral anticoagulants (DOACs) can be associated with an increased risk of heavy menstrual bleeding (HMB) compared with vitamin K antagonists. These findings come from retrospective or prospective single-center studies and post hoc analysis of regulatory studies in which HMB was not a predefined safety outcome. In most of these publications, there is a lack of information about the use of different contraceptive methods which can influence HMB. Another limitation is the various definitions of HMB, which makes comparison between studies regarding the incidences of HMB difficult.

Therefore, prospective studies are urgently needed to investigate the severity and duration of unaffected menstrual bleeding under oral anticoagulation independently of oral contraceptives or intrauterine devices. An ongoing multicenter German registry is aiming to compare the incidence of unaffected HMB in consecutive women of reproductive age (18–50 years) treated with different DOACs because of venous thromboembolism.

When HMB occurs during oral anticoagulation, management includes interruption or dose reduction of anticoagulation with the danger of recurrent venous thrombosis, switch to another oral anticoagulant, or additional use of the antifibrinolytic agent tranexamic acid with the potential risk of thrombosis. Concomitant use of either oral hormonal contraceptive therapy or hormone-releasing intrauterine systems can also reduce HMB.

Thromboembolic Antiphospholipid Syndrome (APS): Efficacy and Safety of Different Anticoagulants-Results of the APSantiCO Registry

Background: The particular challenge in dealing with patients with thromboembolic antiphospholipid syndrome (APS) is to establish an adequate therapy regime, as patients suffer from an increased risk of relapse despite antithrombotic treatment (ATT). Vitamin K antagonists (VKA) are the standard medication of choice. The current data on the use of direct oral anticoagulants (DOAC) in APS patients remain limited. Methods: The results of the retrospective APSantiCO registry are presented. In 80 patients with APS, the efficacy and safety of different ATT regimens were analyzed. Results: At the time of inclusion, 43.8% of patients were treated with VKA and 36.3% with DOAC. Medication regimes changed several times and 279 treatment phases were further analyzed with a total treatment length of 7529 months. The incidence of recurrent arterial thrombosis was significantly larger in the DOAC group compared with the VKA group (p < 0.001), while the incidence of recurrent venous thrombosis was comparable between both groups, as was the incidence of bleedings. Heavy menstrual bleeding was the most frequently observed bleeding complication. Conclusions: The data suggest that DOAC may be an alternative to VKA for APS patients with venous thromboembolism, while VKA should be used in APS-related arterial thrombosis.

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.

Fondaparinux Pre-, Peri-, and/or Postpartum for the Prophylaxis/Treatment of Venous Thromboembolism (FondaPPP)

We analyzed data for women who received fondaparinux for ≥7 days during pregnancy. The study retrospectively included women who received fondaparinux pre-, peri- and/or postpartum for ≥7 days for prophylaxis/venous thromboembolism (VTE) treatment at German specialist centers (2004-2010). Data on pregnancy, VTE risk factors, anticoagulant treatment, pregnancy outcome and adverse events were extracted from medical records. 120 women (mean age 31.5 years) were included. Among 84 women with prior pregnancies, 41.0% had ≥1 abortion. Anticoagulation was indicated for prophylaxis in 92.5% cases, including 82.5% women with an elevated VTE risk (82.8% thrombophilia, 34.2% VTE history). All women received low-molecular-weight heparin (LMWH) as first-line therapy; 3 also unfractionated heparin. Treatment changed to fondaparinux, due to heparin allergy (41.7%) or heparin-induced thrombocytopenia (10.0%). Fondaparinux was generally well tolerated. Adverse events included bleeding events (n = 5), abortion (n = 2), premature births (n = 2), stillbirth (n = 1), arrested labors (n = 2), injection site erythema (n = 4) and unspecified drug hypersensitivity (n = 6). No VTE events or increased liver enzymes occurred during treatment. In this retrospective study, fondaparinux was effective and well tolerated. Trial registration: ClinicalTrials.gov NCT01004939.

2021 Update of the International Council for Standardization in Haematology Recommendations for Laboratory Measurement of Direct Oral Anticoagulants

In 2018, the International Council for Standardization in Haematology (ICSH) published a consensus document providing guidance for laboratories on measuring direct oral anticoagulants (DOACs). Since that publication, several significant changes related to DOACs have occurred, including the approval of a new DOAC by the Food and Drug Administration, betrixaban, and a specific DOAC reversal agent intended for use when the reversal of anticoagulation with apixaban or rivaroxaban is needed due to life-threatening or uncontrolled bleeding, andexanet alfa. In addition, this ICSH Working Party recognized areas where additional information was warranted, including patient population considerations and updates in point-of-care testing. The information in this manuscript supplements our previous ICSH DOAC laboratory guidance document. The recommendations provided are based on (1) information from peer-reviewed publications about laboratory measurement of DOACs, (2) contributing author's personal experience/expert opinion and (3) good laboratory practice.

Direct oral anticoagulants in point-of-care monitoring: an ex-vivo study

BACKGROUND

Anticoagulatory activity of direct oral anticoagulants (DOACs) is not routinely measurable by point-of-care monitoring. Thus, the aim of this study was to evaluate the influence of dabigatran/rivaroxaban on point-of-care testing.

METHODS

Samples from 34 participants under DOAC therapy were drawn at two time points. Before ingestion and two-to-three hours afterwards. Thrombelastometric (ROTEM) and aggregometric (Multiplate) measurements were performed. Dabigatran and rivaroxaban plasma levels were determined.

RESULTS

Dabigatran and rivaroxaban plasma levels showed significant correlations with clotting time (CT) in EXTEM (r=0.765, P<0.0001; r=0.689, P<0.0001) and INTEM (r=0.792, P<0.0001; r=0.595, P<0.001). A positive correlation was identified between dabigatran ingestion and maximum-clot-firmness (MCF) (r=0.354, P<0.05) in the EXTEM test, pronounced in the absence of concomitant antiplatelet therapy (r=0.709, P<0.05). EXTEM-MCF positively correlated with the TRAP test in aggregometry (0.662, P<0.05), an effect not observed in patients treated with antiplatelet therapy.

CONCLUSIONS

Prolongation of CT-EXTEM and CT-INTEM indicates delayed initiation of clot formation. The CT-EXTEM seems to facilitate qualitative monitoring of dabigatran. In contrast, qualitative monitoring of rivaroxaban by CT-EXTEM may be limited as rivaroxaban may affect the measurement at therapeutic plasma levels. It seems that clot formation is faster/firmer in the presence of increased dabigatran plasma levels. This can be attributed to a non-dose-dependent effect via increased fibrin polymerization and second to a dose-dependent effect via increased platelet sensitivity to thrombin.

Incidence and severity of postthrombotic syndrome after iliofemoral thrombosis – results of the Iliaca-PTS – Registry

Summary: Background: Deep venous thrombosis (DVT) and in particular, iliofemoral thrombosis (IFT) can lead to recurrent thrombosis and postthrombotic syndrome (PTS). Data on the prevalence, predictors and outcome of IFT are scarce. Patients and methods: We retrospectively searched our database of outpatients who had presented with DVT and IFT including the iliac veins from 2014 until 2017. In addition, we performed a prospective registry in a subgroup of patients with IFT. These patients received duplex ultrasound, magnetic resonance venography and measurement of symptom-free walking distance using a standardized treadmill ergometry. The severity of PTS was analyzed using the Villalta-Scale (VS) and quality of life was assessed using the VEINES-QOL/Sym Questionnaire. Results: 847 patients were retrospectively identified with DVT and 19.7% (167/847) of these presented with IFT. 50.9% (85/167) of the IFT-patients agreed to participate in the prospective registry. The majority of these patients (76.5%: 65/85) presented with left-sided IFT. In 53.8% (35/65) May-Thurner syndrome was suspected. 27.1% (23/85) underwent invasive therapy. Moderate or severe PTS (VS ≥ 10) occurred in 10.6% (9/85). The severity of PTS is correlated with a reduced quality of life (ρ (CI 95%) = −0.63 (−0.76; −0.46); p < 0.01). None of the patients presented with a venous ulcer at any time. A high body mass index was a significant predictor (OR (CI 95%) = 1.18 (1.05; 1.33), p = 0.007) for the development of clinically relevant PTS (VS ≥ 10) and venous claudication. Conclusions: Every fifth patient with DVT presented with an IFT. The majority developed left sided IFT. Every 10th patient developed moderate or severe PTS (VS ≥ 10). A high body mass index was predictive for the development of PTS and venous claudication.

Real world experience from 1000 patients. Preprocedural DOAC interruption impacts detectable DOAC serum levels but not adverse events after catheter ablation of atrial fibrillation

Introduction

Direct oral anticoagulation (DOAC) therapy represents the standard of care in patients with atrial fibrillation (AF) and increased stroke risk. In a real world setting withholding DOAC medication before elective AF ablation is considered to reduce procedural bleeding risks. The aim of this study was to determine the individual DOAC level prior to the ablation procedure, to identify predisposing factors affecting traceable DOAC levels and to screen for associated severe adverse events.

Methods

Between September 2016 and March 2019 blood samples were obtained from patients on DOAC before an elective AF ablation. Per institutional standard all patients have been instructed to pause DOAC medication prior ablation for one or two doses depending on the patient profile and type of medication. The time interval between ablation and last DOAC intake was calculated in hours. Patient characteristics, procedural data and in-hospital complications were noted from all patients.

Results

A total of 1000 patients (60% male, age: 68y, GFR 83.25: BMI: 28, CHADSVASC score 3) undergoing AF ablation were included. Two groups were defined. Group A (n=416, 41.6%): patients treated with “single pill” DOAC (Rivaroxaban (n=288, 28.8%) and Edoxaban (n=128, 12.8%)). Group B (n=584, 58.4%): patients treated with twice a day DOAC (Apixaban (n=505, 50.5%) and Dabigatran (n=79, 7.9%)). The only difference in patient characteristics was an increased prior bleeding history in group B. The DOAC pause was significantly longer in group A (mean 40h) compared to group B (mean 32h), p=0.026. In a total of 217 patients (21.7%) DOAC levels where traceable prior to AF ablation. Traceable DOAC levels were significantly more common in group B (n=144/584, 24.7%) compared to group A (n=73/416, 17.5%). Adverse events occurred in 5.7% of patients (0.4% stroke, 0.3% tamponade, 2.5% hematoma, 1.9% AV-fistel, 0.7% pseudoaneurysma). T-Test analysis showed no significant difference in the occurrence of adverse events between both groups.

Conclusion

Despite of interrupting DOACs before an elective AF ablation therapeutic substance levels can be detected in &gt;20% of patients. The rate of adverse events was not different between “single pill” vs. twice a day DOAC intake.

Funding Acknowledgement

Type of funding source: None

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.

Treatment of Vascular Thrombosis in Antiphospholipid Syndrome: An Update

The antiphospholipid syndrome (APS) is an acquired autoimmune disorder associated with arterial, venous, or microvascular thrombosis and/or pregnancy complications mainly in young age. The diagnosis is made by the persistent detection of anticardiolipin antibodies, β2-glycoprotein I antibodies (β2GPIA), and/or lupus anticoagulants (LAs) for at least 12 weeks. Patients should present with at least one clinical and one laboratory criterion. Patients presenting with all three types of antibodies and vascular events are high-risk patients and should receive vitamin K antagonists (VKAs) as long as the antibodies persist. In patients with prior arterial thrombosis, VKA with or without low-dose aspirin is the current treatment of choice. The international normalized ratio (INR) should be between 2 and 3 although in some cases keeping the target INR above 3 may be necessary. Patients with venous thrombosis and negative LA may alternatively be treated with direct oral anticoagulants although more data are needed. Minimizing vascular risk factors is always necessary in APS patients. Aspirin can be given as primary prevention in asymptomatic patients with positive antiphospholipid antibodies without thrombosis or pregnancy complications especially when additional vascular risk factors are present. Catastrophic APS occurs in less than 1% of APS patients and presents as a thrombotic storm. Early use of a combined triple therapy such as anticoagulation, plasma exchange, and steroids with either or not addition of immunoglobulins is important to reduce mortality.

Treatment of the antiphospholipid syndrome with direct oral anticoagulantsPosition statement of German societies

The antiphospholipid-syndrome (APS) is one of the most severe forms of thrombophilia, which may not only lead to recurrent venous but also to arterial thromboembolic events (TE), and to severe pregnancy complications, respectively. APS is defined by clinical symptoms and specific laboratory findings: 1. Lupus anticoagulant (LA), 2. anticardiolipin-antibodies (ACA), and 3. β2-Glycoprotein I-antibodies (β2GPI-Ab). All test results have to be confirmed after at least 12 weeks. The thrombotic risk is highest, if all 3 test groups are positive. It must be pointed out that the presence of UFH, VKA or DOACs may lead to false positive LA-test results; the addition of a specific absorber after blood sampling may provide reliable results in the presence of DOACs. A prospective randomized controlled trial comparing warfarin and rivaroxaban (TRAPS-trial) including only high-risk patients with triple positive APS was terminated early because of an increased rate of TE in patients treated with rivaroxaban [19 %, mostly arterial, compared to 3 % with warfarin (HR 7.4;1.7-32.9)]. Subsequently, a warning letter was issued by the pharmaceutical manufacturers of DOACs, including a warning of DOAC use in APS-patients, particularly in triple-positive high-risk patients. Conclusions: 1. Clinical suspicion of APS requires careful diagnostic testing. Because of inadequate diagnostic workup, many patients may not even have an APS, and these patients could be adequately treated with a DOAC. 2. Patients with single or double positive antiphospholipid antibodies but without positive LA may have a comparably low thrombotic risk and may also be treated with a DOAC in venous TE - sufficient evidence for that conclusion is not yet available but is suggested by the results of meta-analyses. 3. Triple positive patients or those with APS who suffered from arterial thromboembolism have a very high recurrence risk of thrombosis; the TRAPS-Study shows that these patients should be treated with VKA instead of a DOAC.

Evaluation of the sensitivity and specificity of a novel line immunoassay for the detection of criteria and non-criteria antiphospholipid antibodies in comparison to established ELISAs

Background

Persistent antiphospholipid antibodies (aPL) constitute the serological hallmark of the antiphospholipid syndrome (APS). Recently, various new assay technologies for the detection of aPL better suited to multiplex reaction environments than ELISAs emerged. We evaluated the diagnostic performance of such a novel line immunoassay (LIA) for the simultaneous detection of 10 different aPL.

Methods

Fifty-three APS patients and 34 healthy controls were investigated for criteria (antibodies against cardiolipin [aCL], β2-glycoprotein I [aβ2-GPI]) and non-criteria aPL (antibodies against phosphatidic acid [aPA], phosphatidyl-choline [aPC], -ethanolamine [aPE], -glycerol [aPG], -inositol [aPI], -serine [aPS], annexin V [aAnnV], prothrombin [aPT]) IgG and IgM by LIA. Criteria aPL were additionally determined with the established Alegria (ALE), AcuStar (ACU), UniCap (UNI), and AESKULISA (AES) systems and non-criteria aPL with the AES system. Diagnostic performance was evaluated with a gold standard for criteria aPL derived from the results of the four established assays via latent class analysis and with the clinical diagnosis as gold standard for non-criteria aPL.

Results

Assay performance of the LIA for criteria aPL was comparable to that of ALE, ACU, UNI, and AES. For non-criteria aPL, sensitivities of the LIA for aPA-, aPI-, aPS-IgG and aPA-IgM were significantly higher and for aPC-, aPE-, aAnnV-IgG and aPC- and aPE-IgM significantly lower than AES. Specificities did not differ significantly.

Conclusions

The LIA constitutes a valuable diagnostic tool for aPL profiling. It offers increased sensitivity for the detection of aPL against anionic phospholipids. In contrast, ELISAs exhibit strengths for the sensitive detection of aPL against neutral phospholipids.

Therapie des Antiphosphoplidsyndrom (APS) mit DOAK

Das Antiphospholipid-Syndrom ist eine der schwerwiegendsten thrombophilen Störungen, die nicht nur zu rezidivierenden venösen, sondern auch zu arteriellen Thromboembolien sowie Schwangerschaftskomplikationen führen kann. Zusammen mit dem klinischen Bild ist das APS durch spezifische Laborbefunde charakterisiert: 1. Lupus Antikoagulans (LA), 2. Anticardiolipin-Antikörper (ACA), 3. β2-Glykoprotein I-Antikörper (β2GPI-AK). Alle Testergebnisse müssen nach 12 Wochen bestätigt werden. Sind alle drei Testgruppen positiv, besteht das höchste thrombotische Risiko. Beachtet werden muss, dass LA-Tests unter UFH, VKA oder DOAKs falsch positiv ausfallen können; bei DOAKs scheint die Zugabe von Absorbern nach Blutentnahme zuverlässige Ergebnisse zu liefern.

Eine Vergleichsstudie (TRAPS) zwischen VKA und dem DOAK Rivaroxaban mit ausschliesslich 3-fach positiven Hochrisiko-Patienten wurde vorzeitig abgebrochen, wegen erhöhter Ereignisraten unter Rivaroxaban [19 % zumeist arterielle Ereignisse versus 3 % unter Warfarin (HR 7.4; 1.7–32.9)]. Ein daraufhin herausgegebener Rote-Hand-Brief warnt vor der Anwendung von DOAKs bei Patienten mit APS, insbesondere bei Hoch-Risiko- (3-fach positiven) Patienten, und empfiehlt die Überprüfung einer laufenden DOAK-Therapie und eine mögliche Umstellung auf VKA, insbesondere bei Hoch-Risiko-Patienten. Als Fazit soll 1. bei klinischem Verdacht eine sorgfältige APS-Diagnostik erfolgen. Viele Patienten haben aufgrund von inadäquater Diagnostik wahrscheinlich gar kein APS und können bei venöser Thromboembolie adäquat ein DOAK erhalten.

2. Bei einfach- oder zweifach-positiven Antiphospholipid-AK Tests ohne LA besteht ein vergleichbar niedriges Thromboserisiko; auch hier kann möglicherweise ebenfalls mit DOAKs behandelt werden, wenn venöse Thrombosen vorliegen – ausreichende Daten liegen noch nicht vor, aber Metaanalysen legen dies nahe. 3. Patienten mit Positivität in allen 3 APS-Tests und APS-Patienten mit arteriellen Thromboembolien haben ein sehr hohes Risiko. Die TRAPS-Studie zeigt, dass diese Patienten nicht mit DOAKs, sondern mit einem VKA behandelt werden sollen.

[Modern treatment of deep vein thrombosis and pulmonary embolism]

Virchow's triad has been known for a 100 years. The development of therapeutic possibilities during this time was enormous. Today anticoagulant therapy is much more differentiated. Four new oral substances have replaced the traditional treatment with vitamin K antagonists in angiology. A standardized dosage is available. The monitoring of the coagulation parameters is no longer necessary, but it is important to monitor renal function. Direct oral anticoagulants are approved for the treatment of venous thrombosis and pulmonary embolism, but not during pregnancy or in children. Severe bleeding complications, especially intracerebral bleeding, are less common. The incidence of venous thromboembolism is still high. Obesity and cancer are of particular importance. The "therapeutic pact" with the patient requires that physicians master the art of "talking medicine".

International Council for Standardization in Haematology (ICSH) Recommendations for Laboratory Measurement of Direct Oral Anticoagulants

This guidance document was prepared on behalf of the International Council for Standardization in Haematology (ICSH) for providing haemostasis-related guidance documents for clinical laboratories. This inaugural coagulation ICSH document was developed by an ad hoc committee, comprised of international clinical and laboratory direct acting oral anticoagulant (DOAC) experts. The committee developed consensus recommendations for laboratory measurement of DOACs (dabigatran, rivaroxaban, apixaban and edoxaban), which would be germane for laboratories assessing DOAC anticoagulation. This guidance document addresses all phases of laboratory DOAC measurements, including pre-analytical (e.g. preferred time sample collection, preferred sample type, sample stability), analytical (gold standard method, screening and quantifying methods) and post analytical (e.g. reporting units, quality assurance). The committee addressed the use and limitations of screening tests such as prothrombin time, activated partial thromboplastin time as well as viscoelastic measurements of clotting blood and point of care methods. Additionally, the committee provided recommendations for the proper validation or verification of performance of laboratory assays prior to implementation for clinical use, and external quality assurance to provide continuous assessment of testing and reporting method.

Heparin-induced skin lesions

Cutaneous reactions to subcutaneous heparin injections have been described first in 1952. These reactions may be caused by several mechanisms such as immediate or delayed-type hypersensitivity responses, or by life-threatening immune-mediated heparin-induced thrombocytopenia (HIT). In contrast to bleeding, induction of osteoporosis and hair loss, no data on the incidence and causes of heparin-induced skin lesions had been available until recently. In a large prospective epidemiological study, the incidence of heparin-induced skin lesions was as high as 7.5% in medical patients, far exceeding the expected incidence. As heparin-induced skin lesions may be the sole clinical manifestation of immune HIT, rapid and valid diagnosis of heparin-induced skin lesions is of utmost clinical importance. Therefore, we have reviewed all known causes of heparin-induced skin lesions, and propose diagnostic and therapeutic procedures.

Diagnosis of heparin-induced delayed type hypersensitivity

Heparin is commonly used for prevention and therapy of thromboembolic diseases. Recently, work from a prospective epidemiological investigation has indicated, that heparin-induced skin lesions may be more frequent, than expected. Commonly, delayed-type hypersensitivity reactions can be identified as the cause of heparin-induced skin lesions. Rarely, immediatetype hypersensitivity responses or immune-mediated heparin-induced thrombocytopenia (HIT) are diagnosed. It is of clinical importance to differentiate between those, as patient management is fundamentally different. Patients, methods: We evaluated diagnostic procedures used to identify causes of heparin-induced skin lesions. Based on clinical presentation, histology and/or allergologic testing in 32 patients, heparin-induced delayed-type hypersensitivity (HIHS) was diagnosed. Results: Sensitivity of histology and s.c. provocation was high, amounting to 100% or 78% respectively. All other tests were unspecific or had a low sensitivity: Immediate readings of prick tests were false negative in 81%. Patch, prick and i.c. testing had a sensitivity ranging from 3.1–15.6%. Conclusion: Based on these results and despite the limitations of histology we recommend performing a skin biopsy rather than allergologic testing for diagnosis of HIHS. Compared to allergologic testing, results from histology are sensitive, readily available and may allow a differentiation from other causes of heparin-induced skin lesions.

Peak and baseline concentrations of fondaparinux during prophylactic therapy

Fondaparinux is widely approved for prophylaxis and treatment of venous thromboembolic events (VTE). However, its longer half-life time compared to heparins limits its peri-procedural use.

Aim: To investigate 3h peak and 24h baseline concentrations of fondaparinux when administered for prophylaxis (1 x 2.5 mg qd). Secondary outcome measures: incidences of VTE, bleedings, HIT, allergic skin reactions, 30 days mortality.

Patients, methods: Between 02/2010 and 03/2011, 3h peak and 24h baseline levels of fondaparinux were measured with a chromogenic anti-FXa method in 75 consecutive patients. Medical data were obtained from patients' records.

Results: The 5% and 95% percentile of the 3h peak level were 0.20 μg/ml and 0.83 μg/ml (median: 0.53 μg/ml), and of the 24h baseline level 0.08 μg/ml and 0.53 μg/ml (median 0.21 μg/ml), respectively. An inverse correlation was found between fondaparinux levels and GFRs (rho=-0.617 (3h); rho=-0.648 (24h); p=0.01). Shorter (≤5 days) or longer (≥8 days) duration of prior fondaparinux exposure showed no significantly different 3h peak/24h baseline levels (p>0.6). One progressive thrombosis occurred but no major bleedings, HIT, allergic skin reactions or fatalities.

Conclusions: After fondaparinux exposure, >75% of the patients still had relevant prophylactic 24h baseline levels. This did not coincide with a high rate of bleeding events. Due to the low patient number in this study undergoing surgery or interventions, it remains to be investigated whether or at which concentrations the bleeding risk is increased when baseline levels are within prophylactic ranges.

Blutungsrisiko und Blutungsnotfälle unter Rivaroxaban

Rivaroxaban, the first direct factor-Xa inhibitor anticoagulant, has been approved for the prevention of venous thromboembolism in adult patients undergoing elective hip or knee replacement surgery, for stroke prophylaxis in patients with non-valvular atrial fibrillation and for the treatment of deep vein thrombosis. There is no requirement for coagulation monitoring with rivaroxaban in routine clinical practice. However, in certain clinical circumstances such as life-threatening bleeding or an emergency operation the measurement of the thromboplastin time with a sensitive reagent will deliver first information. A quantitative determination of rivaroxaban plasma concentration is possible using an anti-factor Xa assay.

In the case of a patient under long-term anticoagulation with rivaroxaban requiring an elective surgery, a discontinuation of rivaroxaban 20 to 30 hours before the operation is sufficient to normalize the associated bleeding risk, as long as the renal and liver function is normal. A longer interval should be taken into consideration, when the patient presents a renal and liver impairment or is of a higher age. In the event of an emergency operation effective rivaroxaban concentrations might be present. Nevertheless, we advise against using a prophylactic dose of factor concentrates. Recommendations: From a clinical perspective, in the event of a minor bleeding we recommend a temporary discontinuation of rivaroxaban, whereas for clinically relevant major or severe bleeding events a mechanical compression or a limited surgical i. e. interventional treatment is required. Supportive measures such as the administration of blood products or tranexamic acid might be beneficial. In addition to haemodynamic supportive measures life threatening bleeding events demand a comprehensive haemostasis management, as well as the application of PCC.

Therapie mit Dabigatran

Summary Dabigatran, an oral, reversible direct factor IIa inhibitor, is approved in Europe for stroke prevention in atrial fibrillation and for the prevention of venous thromboembolism after elective hip and knee replacement. In contrast to vitamin K antagonists, a routine coagulation monitoring during the treatment with dabigatran etexilate is not necessary. However, in specific clinical situations such as invasive emergency procedures or serious haemorrhage, the actual anticoagulant status of dabigatran may be of importance for the treating clinician and can be assessed by clotting tests (aPTT, TT, ECT). The diluted thrombin time test (Hemoclot®), which is specifically calibrated for dabigatran, is useful for quantitative determination of the dabigatran serum concentration. In general, discontinuation of dabigatran etexilate 24 hours before standard elective surgery is sufficient to normalise the bleeding risk in patients with normal renal function. In patients with renal impairment and/or in the case of a high bleeding risk procedure the recommended duration of discontinuation is prolonged. If a bleeding episode occurs in a patient on dabigatran, further treatment should be based on the severity and localisation of the bleeding. A distinct feature of dabigatran is the possibility of effectively removing dabigatran from the circulation by haemodialysis. Recommendation: In the case of clinically minor bleedings, a delay in the administration of the next dabigatran etexilate dose is recommended. The length of the delay is based on the patient’s individual thromboembolic risk. In minor bleedings the use of prothrombin complex concentrates is not indicated. In the case of moderate or major bleedings the main focus should be on stabilising the circulation by using fluids and blood products and, if a lesion can be identified, the local treatment thereof. If time and infrastructure is available, dialysis offers an effective and fast option to remove dabigatran out of the circulation. In the incidence of severe and life threatening bleedings, an additional, more complex haemostasis management is required. Besides haemodynamic stabilisation of the circulation, administration of prothrombin complex concentrates should not be delayed. It has to be kept in mind that standard laboratory coagulation parameters may not accurately reflect the effect of prothrombin complex concentrates in patients on dabigatran. Hence the effect of the prothrombin complex concentrate should be monitored clinically and adjusted by means of onset of coagulation in vivo.

Direct oral anticoagulants (DOAC) - Management of emergency situations

The worldwide increase in the aging population and the associated increase in the prevalence of atrial fibrillation and venous thromboembolism as well as the widespread use of direct oral anticoagulants (DOAC) have resulted in an increase of the need for the management of bleeding complications and emergency operations in frail, elderly patients, in clinical practice. When severe bleeding occurs, general assessment should include evaluation of the bleeding site, onset and severity of bleeding, renal function, and concurrent medications with focus on anti-platelet drugs and nonsteroidal anti-inflammatory drugs (NSAID). The last intake of the DOAC and its residual concentration are also relevant. The site of bleeding should be immediately localized, anticoagulation should be interrupted, and local measures to stop bleeding should be taken. In life-threatening bleeding or emergency operations immediate reversal of the antithrombotic effect may be indicated. If relevant residual DOAC-concentrations are expected and surgery cannot be postponed, prothrombin complex concentrate (PCC) and/or a specific antidote should be given. While idarucizumab, the specific antidote for dabigatran, has been recently approved for clinical use, the recombinant factor X protein andexanet alfa, an antidote for the reversal of inhibitors of coagulation factor Xa, and ciraparantag, a universal antidote, are not available. Future cohort studies are necessary to assess the efficacy and safety of specific and unspecific reversal agents in "real-life" conditions. This was the rationale for introducing the RADOA-registry (RADOA: Reversal Agent use in patients treated with Direct Oral Anticoagulants or vitamin K antagonists), a prospective non-interventional registry, which will evaluate the effects of specific and unspecific reversal agents in patients with life-threatening bleeding or emergency operations either treated with DOACs or vitamin K antagonists.

Fortschritte in der Thrombozytenfunktionsdiagnostik

Both for diagnosis of congenital and acquired platelet dysfunction as well as for therapy monitoring after application of platelet function inhibitors various methods have been established for evaluation of platelet function. In contrast to the gold standard of platelet function testing, the light transmission aggregometry in platelet rich plasma the Point-of-care (POC) analyzers allow fast analysis of platelet function without extensive laboratory work up. The conditions of the pre-analytical phase, however, are still of enormous importance in the prevention of medical errors. There is increasing clinical data in monitoring the effect of platelet aggregation inhibitors, showing that quantitative determination of the platelet function degree correlates with risk of increased bleeding or stent thrombosis. However, it is still unclear, which is the optimal test system, to predict the clinical outcome of these patients.

Danaparoid in der Schwangerschaft bei Heparinunverträglichkeit

Unter Therapie mit unfraktioniertem oder niedermolekularem Heparin treten häufig unerwünschte Arzneimittelwirkungen auf, die eine Fortsetzung der Therapie unmöglich machen. Insbesondere bei Schwangeren mit thromboembolischen Komplikationen kann es schwierig sein, ein geeignetes alternatives Antikoagulans zu finden, wenn zusätzlich eine Heparinunverträglichkeit vorliegt. Für den Einsatz von Danaparoid in der Schwangerschaft gibt es nur wenige Daten. Die Hauptgründe in den untersuchten 59 Schwangerschaften für eine Heparinunverträglichkeit waren entweder eine HIT II bei 37/59 (62,7%) Schwangeren, oder eine kutane Nebenwirkung in 19/22 (86,4%) der nicht HIT-assoziierten Schwangerschaften (22/59, 37,3%). Ergebnisse: 40/59 Schwangerschaften konnten unter Danaparoid erfolgreich ausgetragen werden, bei 16/19 wurde die Therapie aufgrund unerwünschter Arzneimittelwirkungen beendet. Fünf Patientinnen zeigten Blutungskomplikationen, die ebenso wenig Danaparoid-assoziiert waren wie die berichteten sechs Aborte und eine Abruptio. In 31/59 (52,5%) Schwangerschaften traten unerwünschte Arzneimittelwirkungen auf, 14/31 (45,2%) ließen sich auf Danaparoid zurückführen. In fünf Nabelschnurblut- und vier Brustmilchproben konnte keine Anti- Xa-Aktivität gemessen werden. Schlussfolgerung: Danaparoid kann zur alternativen Antikoagulation bei Schwangeren mit hohem Thromboserisiko und Heparinunverträglichkeit eingesetzt werden.

Überwachung der Antikoagulanzientherapie mit Fondaparinux

Im Gegensatz zu niedermolekularem und unfraktioniertem Heparin besitzt Fondaparinux, ein synthetisch hergestelltes Pentasaccharid, einen selektiv hemmenden Effekt auf den Gerinnungsfaktor X. Die Substanz ist seit drei Jahren zur Hochrisikothromboseprophylaxe nach großen orthopädischen Operationen zugelassen. Auf Grund der ausgezeichneten Bioverfügbarkeit nach subkutaner Gabe, die einmal pro Tag in körpergewichtsunabhängiger Dosierung (bei einem Körpergewicht von 50-100 kg) erfolgen kann, ist normalerweise ein Monitoring nicht erforderlich. Insbesondere seit der europaweiten Zulassung zur Therapie venöser Thrombosen ist jedoch im Ausnahmefall (z. B. Verdacht auf Fehldosierung, bei Niereninsuffizienz oder Blutungen) ein Monitoring im Routinelabor sinnvoll.

Inzwischen wurden chromogene Substratmethoden, basierend auf zur Verfügung stehenden Monitoring-Methoden zur Messung des Faktor Xa inhibierenden Effektes der niedermolekularen Heparine, publiziert. Unter Berücksichtigung dieser Publikationen sollte Fondaparinux als Kalibrator verwendet und die Einheiten in μg/ml angegeben werden. Wegen der synthetischen Herstellung der Substanz findet sich eine lineare Dosis/Wirkungsbeziehung in einem weiten Konzentrationsbereich, so dass eine sehr gute Präzision der Methodik an Vollautomaten erreicht werden kann.

Resistenz gegen Azetylsalizylsäure und Clopidogrel

Resistenz gegen Azetylsalizylsäure (ASS) bzw. Clopidogrel wird vom klinischen Gesichtspunkt als Unvermögen des Wirkstoffs angesehen, rezidivierende arterielle Gefäßverschlüsse zu verhindern. Aus laborchemischer Sicht hingegen wird die Non-Response gegenüber ASS und Clopidogrel als das Ausbleiben eines erwarteten Effektes in verschiedenen Thrombozytenfunktionstestsystemen beschrieben. Etablierte Thrombozytenfunktionsteste ermöglichen meist keine spezifischen Aussagen über die Thrombozytenaggregationshemmung durch ASS oder Clopidogrel. Wünschenswert wäre, die ASS- und Clopidogrel-Non-Response mit Plättchenfunktionstesten derart zu ermitteln, dass isoliert die spezifischen Effekte dieser Arzneimittel erfasst werden. Im Idealfall könnte eine solche Labordiagnostik helfen, klinische Ereignisse aufgrund eines Therapieversagens im Vorfeld zu verhindern. Studien, die eine Prävalenz von 5 bis 59% für die ASS- oder Clopidogrel-Non-Response angeben, geben erste Hinweise dafür, dass der Nachweis einer laborchemischen ASS- oder Clopidogrel-Non-Response mit dem nachfolgendem Auftreten vaskulärer Reereignisse assoziiert sein könnte. Allerdings sind diese Studien durch zu geringe Fallzahlen, fehlende Standardisierung der Labormethoden und sehr differente Einschlusskriterien in ihrer Aussagekraft limitiert. Deshalb bleibt die klinische Relevanz laborchemisch nachgewiesener ASS- oder Clopidogrel- Resistenz unklar und sollte umgehend in prospektiven Multizenterstudien geklärt werden. Die individuellen Ursachen einer reduzierten oder ausbleibenden Wirkung von ASS oder Clopidogrel können multifaktoriell sein. Die Mechanismen der ASS- bzw. Clopidogrel- Resistenz sind weitgehend ungeklärt.

Molecular weight determines the frequency of delayed type hypersensitivity reactions to heparin and synthetic oligosaccharides

Eczematous lesions, resulting from type IV sensitizations are well-known and relatively frequent cutaneous adverse effects of s.c. heparin therapy. If anticoagulation is further required intravenous heparin, heparinoids or lepirudin may be used as a substitute. However, these alternatives are not optimal in terms of practicability and/or safety-profiles. As molecular weight of different heparin preparations has repetitively been implied to determine the frequency of sensitization, we hypothesized, that due to its low molecular weight the pentasaccharide fondaparinux may provide a practicable and safe anticoagulant therapy in patients with delayed type hypersensitivity reactions (DTH) to heparin and other oligosaccharides. To test this concept, patients referred for diagnosis of cutaneous reactions after s.c. anticoagulant treatment underwent a series of in vivo skin allergyand challenge-tests with unfractionated heparin, a series of low molecular weight heparins (nadroparin, dalteparin, tinzaparin, enoxaparin and certoparin), the heparinoid danaparoid and the synthetic pentasaccharide fondaparinux. In total, data from twelve patients was evaluated. In accordance with previously published data, we report a high crossreactivity among heparins and heparinoids. In contrast – and in support of our initial hypothesis – sensitization towards the synthetic pentasaccharide fondaparinux was rarely observed. Plotting the cumulative incidence against the determined molecular weight of the individual anticoagulant preparations, shows that molecular weight generally is a key determinant of sensitization towards heparins and other oligosaccharides (r2=0.842, p=0.009). Hence, fondaparinux may be used as a therapeutic alternative in patients with cutaneous DTH relations towards heparin and other polysaccharides.

Management of cutaneous type IV hypersensitivity reactions induced by heparin

Localized hypersensitivity reactions to subcutaneous heparin injections have been described since 1952. Yet, the incidence of these reactions, which are distinct from skin lesions associated with heparin-induced thrombocytopenia type II (HIT II), remains uncertain. However, in the last 10 years an increasing number of patients have been reported, leading to the assumption that cutaneous hypersensitivity reactions towards heparin are underreported. Clinically patients present with itching, sometimes infiltrated, and blistering erythemas at the injection sites of heparins. The diagnosis of cutaneous heparin allergy may, on the one hand, lead to delay of required medical or surgical treatment. On the other hand, delayed initiation of treatment may lead to a generalized eczematous reaction. Hence, from review of 223 cases of patients with cutaneous hypersensitivity reactions to heparin, we here summarize the clinical picture of cutaneous type IV allergic reactions, define risk factors on both the patient- and drug-side, and give an overview of principle therapeutic alternatives, as well as recommendations for treatment options for emergency and elective patients. As the proposed management of patients with cutaneous hypersensitivity reactions to heparin may have fatal consequences when applied in patients with HIT type II, diagnosis of skin lesions in heparin-treated patients needs to be precise.

Association of ADAMDEC1 haplotype with high factor VIII levels in venous thromboembolism

A suggestive locus on chromosome 8 could be shown to be associated with familial high factor VIII (FVIII) levels in venous thromboembolism. The ADAMDEC 1 gene is a candidate expressing an ectodomain sheddase. However, the ectodomain of the clearance receptor for FVIII, the low-density lipoprotein receptor-related protein (LRP), is subject to proteolysis by metalloproteases like ADAMDEC1. Other LRP-interacting proteins are lipoprotein lipase (LPL) and t-PA. For an association study, 165 thrombotic patients with high FVIII levels (from the MAISTHRO, i.e. Main-Isar-thrombosis register) were included. All patients with known causes for high FVIII levels had been previously excluded. The patients were compared with 214 healthy blood donors. Polymorphisms with usually a minor allele frequency > 5 %, i.e. 24 SNPs and two insertion/deletion polymorphisms of LPL gene, eight SNPs of the t-PA gene, and five SNPs of the ADAMDEC1 gene, were analyzed. Haplotype differences were calculated using PHASE. A new polymorphism in intron 7 of the t-PA gene with a minor allele frequency of 2.2% was identified. Analysis of each SNP by the Cochrane-Armitage trend test did not show any significant association between genotype and disease status. Interestingly, the ADAMDEC1 haplotype (rs12674766, rs10087305, rs2291577, rs2291578, rs3765124) differed between cases and controls (p=0.04). In particular, the TGTGG haplotype showed a difference. In conclusion, the ADAMDEC 1 haplotype may indicate an underlying mechanism for high FVIII levels. The only moderate linkage disequilibrium may be due to a possible causal polymorphism in distant introns or the promoter region against a polygenic background.

Ex vivo effects of low-dose rivaroxaban on specific coagulation assays and coagulation factor activities in patients under real life conditions

Global coagulation assays display variable effects at different concentrations of rivaroxaban. The aim of this study is to quantify the ex vivo effects of low-dose rivaroxaban on thrombophilia screening assays and coagulation factor activities based on the administration time, and to show how to mask possible interferences. Plasma samples from 40 patients receiving rivaroxaban 10 mg daily were investigated to measure activities of clotting factor II, V, VII, VIII, IX, XI, XII and XIII; protein C- and protein S-levels; lupus anticoagulants; anticardiolipin IgG and IgM; D-dimer, heparin-platelet factor 4 (HPF4) antibodies and screening tests for von Willebrand disease (VWD). Two hours after rivaroxaban administration, the activities of clotting factors were significantly decreased to different extents, except for factor XIII. Dilution of plasma samples resulted in neutralisation of these interferences. The chromogenic protein C activity assay was not affected by rivaroxaban. Depending on the timing of tablet intake in relation to blood sampling protein S activity was measured falsely high when a clotting assay was used. False-positive results for lupus anticoagulants were observed depending on the assay system used and the administration time of rivaroxaban. ELISA-based assays such as anticardiolipin IgG and IgM, D-dimer, HPF4-antibodies and the turbidimetric assays for VWD were not affected by rivaroxaban. Specific haemostasis clotting tests should be performed directly prior to rivaroxaban intake. Assay optimisation in the presence of rivaroxaban can be achieved by plasma dilution. Immunologic assays are not influenced by rivaroxaban, while chromogenic assays can be used, when they do not depend on factor Xa.

Rivaroxaban differentially influences ex vivo global coagulation assays based on the administration time

It was the objective of this study to quantify the effects of rivaroxaban administration on global coagulation parameters associated with routine clinical procedures, we collected plasma samples from patients undergoing major orthopaedic surgery receiving rivaroxaban at various time points after drug administration. Forty-seven patients received rivaroxaban (10 mg daily) for venous thromboembolism prophylaxis. Blood samples were collected at four different time points: A) before surgery; B) before drug administration at day 4–5 after surgery (steady state of rivaroxaban); C) 2 hours (h) after drug administration and D) 12 h after drug administration. The prothrombin time (PT), activated partial thromboplastin time (aPTT), thrombin time (TT), antithrombin (AT) level, fibrinogen level by Clauss method (FibC), and derived fibrinogen (dFIB) level were assessed with various reagents. At 2 h after rivaroxaban administration, the PT and aPTT clotting times were significantly prolonged to different extents up to 1.4 fold, whereas 12 h after drug administration, no significant effect was observed. Rivaroxaban administration had no influence on the TT or the FibC concentration. The dFIB assay was differentially affected by rivaroxaban when different reagents were tested. The AT assay dependent on thrombin activity was not influenced by rivaroxaban, whereas the AT levels dependent on factor Xa activity were significantly increased by rivaroxaban. Clinicians should be aware of the time-dependent influence of rivaroxaban on factor Xa-dependent routine coagulation assays. Therefore, routine coagulation parameters should be assessed directly before drug administration to keep the interaction of rivaroxaban low.

Hereditary and acquired thrombophilia in patients with upper extremity deep-vein thrombosis

The prevalence of coagulation disorders in patients with upper extremity deep-vein thrombosis (UE-DVT) is unknown due to only a few observational studies of limited size reporting varying results. Therefore, we aimed to evaluate the prevalence of thrombophilia in patients with UE-DVT compared to patients with lower extremity deep vein thrombosis (LE-DVT). One hundred fifty consecutive patients (15 to 91 years of age) with UE-DVT were recruited from the MAISTHRO (MAin-ISar-THROmbosis) registry. Three hundred LE-DVT patients matched for gender and age served as controls. Thrombophilia screening included tests for the factor V Leiden mutation, the prothrombin G20210A mutation, antiphospholipid antibodies and factor VIII (FVIII), protein C, protein S and antithrombin activities. At least one thrombophilia was present in 34.2% of UE-DVT and 39.2% in UE-DVT that was unrelated to venous catheters relative to 55.3% in LE-DVT patients (p<0.001). In particular, a persistently elevated FVIII is less likely to be found in UE-DVT patients than in those with LE-DVT and is the only thrombophilia that is differentially expressed after controlling for established VTE risk factors [OR 0.46, (95% CI 0.25–0.83)]. Although less prevalent than in LE-DVT patients, thrombophilia is a common finding in patients with UE-DVT, especially in those with thrombosis that is unrelated to venous catheters.

Impact of pharmacokinetic (CYP2C9) and pharmacodynamic (VKORC1, F7, GGCX, CALU, EPHX1) gene variants on the initiation and maintenance phases of phenprocoumon therapy

Compared to warfarin, little is known about the effect of pharmacogenomics on the inter-individual variability of phenprocoumon therapy. In a retrospective cohort study, we investigated the impact of VKORC1 c.-1639G>A; CYP2C9*2, CYP2C9*3; GGCX c.214+597G>A; CALU c.*4A>G; EPHX1 c.337T>C; F7 c.-402G>A, and F7 c.-401G>T on the initiation (n=54) and maintenance phases (n=91) of phenprocoumon therapy. We assessed the following outcome parameters: time to stable international normalised ratio (INR), time to first supra-therapeutic INR, time out of INR range, probability of over-anticoagulation, number of anticoagulation clinic visits. During the initiation phase, homozygotes for the VKORC1 c.-1639 A and G alleles achieved stable INRs later (p<0.001), spent more time at supra-therapeutic INRs (p<0.001), had increased risks of over-anticoagulation (odds ratio 19.83, p=0.003 and 4.45, p=0.045, respectively), and had higher frequencies of anticoagulation clinic visits (p<0.001) compared to GA carriers. CYP2C9*2, *3 carriers reached stable INRs faster (p=0.024) with fewer anticoagulation clinic visits (p=0.001) than wild-type carriers. EPHX1 c.337 C carrier spent significantly more time above range in the initiation phase (p=0.023). GGCX, CALU, and F7 gene variants did not affect outcome parameters of the initiation phase and none of the genotypes had an impact on maintenance phase parameters. Compared to the VKORC1 genotype, early INR values were less informative in the prediction of outcome parameters such as time to stable INR and time above the INR range. Our study is limited by the retrospective study design with no standardised protocol in a usual care setting. Therefore, our findings should be validated in a larger, controlled prospective study.

Accurate determination of rivaroxaban levels requires different calibrator sets but not addition of antithrombin

Rivaroxaban is a direct factor Xa inhibitor, which can be monitored by anti-factor Xa chromogenic assays. This ex vivo study evaluated different assays for accurate determination of rivaroxaban levels. Eighty plasma samples from patients receiving rivaroxaban (Xarelto®) 10 mg once daily and 20 plasma samples from healthy volunteers were investigated using one anti-factor Xa assay with the addition of exogenous antithrombin and two assays without the addition of antithrombin. Two different lyophilised rivaroxaban calibration sets were used for each assay (low concentration set: 0, 14.5, 59.6 and 97.1 ng/ml; high concentration set: 0, 48.3, 101.3, 194.2 and 433.3 ng/ml). Using a blinded study design, the rivaroxaban concentrations determined by the assays were compared with concentrations measured by HPLC-MS/MS. All assays showed a linear relationship between the rivaroxaban concentrations measured by HPLC-MS/MS and the optical density of the anti-FXa assays. However, the assay with the addition of exogenous anti-thrombin detected falsely high concentrations of rivaroxaban even in plasma samples from controls who had not taken rivaroxaban (intercept values using the high calibrator set and the low calibrator set: +26.49 ng/ml and +13.71 ng/ml, respectively). Plasma samples, initially determined by the high calibrator setting and containing rivaroxaban concentrations <25 ng/ml, had to be re-run using the low calibrator setting for precise measurement. In conclusion, anti-factor Xa chromogenic assays that use rivaroxaban calibrators at different concentration levels can be used to measure accurately a wide range of rivaroxaban concentrations ex vivo. Assays including exogenous antithrombin are unsuitable for measurement of rivaroxaban.