Incidence and impact of anticoagulation-associated abnormal menstrual bleeding in women after venous thromboembolism.

Preliminary data and clinical experience have suggested an increased risk of abnormal uterine bleeding (AUB) in women of reproductive age treated with anticoagulants, but solid data are lacking. The TEAM-VTE study was an international multicenter prospective cohort study in women aged 18 to 50 years diagnosed with acute venous thromboembolism (VTE). Menstrual blood loss was measured by pictorial blood loss assessment charts at baseline for the last menstrual cycle before VTE diagnosis and prospectively for each cycle during 3 to 6 months of follow-up. AUB was defined as an increased score on the pictorial blood loss assessment chart (>100 or >150) or self-reported AUB. AUB-related quality of life (QoL) was assessed at baseline and the end of follow-up using the Menstrual Bleeding Questionnaire. The study was terminated early because of slow recruitment attributable to the COVID-19 pandemic. Of the 98 women, 65 (66%) met at least one of the 3 definitions of AUB during follow-up (95% confidence interval [CI], 57%-75%). AUB occurred in 60% of women (36 of 60) without AUB before VTE diagnosis (new-onset AUB; 95% CI, 47%-71%). Overall, QoL decreased over time, with a mean Menstrual Bleeding Questionnaire score increase of 5.1 points (95% CI, 2.2-7.9), but this decrease in QoL was observed only among women with new-onset AUB. To conclude, 2 of every 3 women who start anticoagulation for acute VTE experience AUB, with a considerable negative impact on QoL. These findings should be a call to action to increase awareness and provide evidence-based strategies to prevent and treat AUB in this setting. This was an academic study registered at www.clinicaltrials.gov as #NCT04748393; no funding was received.

Treatment of cancer-associated venous thromboembolism in the age of direct oral anticoagulants.

Anticoagulation for cancer-associated venous thromboembolism (VTE) can be challenging due to complications-including bleeding and potential drug-drug interactions with chemotherapy-associated with vitamin K antagonists and inconvenience of low-molecular-weight heparin (LMWH). Direct oral anticoagulants (DOACs) could partially overcome these issues, but until recently there were no large clinical trials assessing their efficacy and safety in cancer patients. This review summarizes clinical treatment guidelines, prior clinical and real-world evidence for anticoagulant choice, recent clinical trials assessing DOACs for cancer-associated VTE (i.e. Hokusai-VTE Cancer, SELECT-D, CARAVAGGIO, and ADAM VTE), and special considerations for DOAC use. Based on established data, clinical guidelines recommend patients with cancer-associated VTE receive LMWH treatment of at least 3-6 months. Nevertheless, LMWH is underused and associated with poor compliance and persistence in these patients relative to oral anticoagulants. Clinical data supporting DOAC use in cancer patients are becoming available. In Hokusai-VTE Cancer, edoxaban was noninferior to dalteparin for the composite of recurrent VTE and major bleeding (12.8% versus 13.5%), with numerically lower recurrent VTE (7.9% versus 11.3%) and significantly higher major bleeding (6.9% versus 4.0%); only patients with gastrointestinal cancer had significantly higher risk of bleeding with edoxaban. In SELECT-D, rivaroxaban had numerically lower VTE recurrence (4% versus 11%), comparable major bleeding (6% versus 4%), and numerically higher clinically relevant nonmajor bleeding (13% versus 4%) versus dalteparin. Most bleeding events were gastrointestinal or urologic; patients with esophageal/gastroesophageal cancer had higher rates of major bleeding with rivaroxaban (36% versus 11%). For comparison of apixaban versus dalteparin, CARAVAGGIO is ongoing, and preliminary results from ADAM VTE are favorable. This review concludes that DOACs appear to be reasonable alternatives to LMWH for treatment of cancer-associated VTE. In patients with gastrointestinal cancer, DOAC use should be considered on a case-by-case basis with consideration of the relative risks and benefits.

[Aggressive treatment of deep vein thrombosis - contra]. / Aggressive Therapie der tiefen Venenthrombose - Kontra.

Together with the classical conservative treatment or the rarely necessary surgical thrombectomy in patients with acute deep vein thrombosis, catheter-directed thrombolysis is becoming more and more popular. This review provides a critical view on the evidence for catheter-directed thrombolysis providing a "Contra" position in contrast to the "Pro" position also published in this issue.

New recommendations on cerebral venous and dural sinus thrombosis from the German consensus-based (S2k) guideline.

Over the last years, new evidence has accumulated on multiple aspects of diagnosis and management of cerebral venous and dural sinus thrombosis (CVT) including identification of new risk factors, studies on interventional treatment as well as treatment with direct oral anticoagulants. Based on the GRADE questions of the European Stroke Organization guideline on this topic, the new German guideline on CVT is a consensus between expert representatives of Austria, Germany and Switzerland. New recommendations include:• CVT occurring in the first weeks after SARS-CoV-2 vaccination with vector vaccines may be associated with severe thrombocytopenia, indicating the presence of a prothrombotic immunogenic cause (Vaccine-induced immune thrombotic thrombocytopenia; VITT).• D-dimer testing to rule out CVT cannot be recommended and should therefore not be routinely performed.• Thrombophilia screening is not generally recommended in patients with CVT. It should be considered in young patients, in spontaneous CVT, in recurrent thrombosis and/or in case of a positive family history of venous thromboembolism, and if a change in therapy results from a positive finding.• Patients with CVT should preferably be treated with low molecular weight heparine (LMWH) instead of unfractionated heparine in the acute phase.• On an individual basis, endovascular recanalization in a neurointerventional center may be considered for patients who deteriorate under adequate anticoagulation.• Despite the overall low level of evidence, surgical decompression should be performed in patients with CVT, parenchymal lesions (congestive edema and/or hemorrhage) and impending incarceration to prevent death.• Following the acute phase, oral anticoagulation with direct oral anticoagulants instead of vitamin K antagonists should be given for 3 to 12 months to enhance recanalization and prevent recurrent CVT as well as extracerebral venous thrombosis.• Women with previous CVT in connection with the use of combined hormonal contraceptives or pregnancy shall refrain from continuing or restarting contraception with oestrogen-progestagen combinations due to an increased risk of recurrence if anticoagulation is no longer used.• Women with previous CVT and without contraindications should receive LMWH prophylaxis during pregnancy and for at least 6 weeks post partum.Although the level of evidence supporting these recommendations is mostly low, evidence from deep venous thrombosis as well as current clinical experience can justify the new recommendations.This article is an abridged translation of the German guideline, which is available online.

[Basics for the Use of Andexanet]. / Grundlagen zur Anwendung von 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.

Determinants of intermediate term clinical outcome after endovascular below-knee interventions.

BACKGROUND: To determine predictors of clinical outcome after endovascular interventions of crural arteries in patients with peripheral arterial disease. PATIENTS AND METHODS: We prospectively followed 154 limbs in 147 patients treated with below the knee endovascular interventions for critical limb ischemia (52 %) and severe claudication (48 %). Patient-immanent, hemodynamic-procedural and anatomic determinants of outcome were analyzed. Outcome was defined as event-free survival from the combined endpoint freedom from re-intervention, major amputation and death. RESULTS: Cumulative event-free survival after 12 months was 65.1 %. During follow-up 42 patients (27.3 %) required re-intervention, 8 (5.2 %) underwent major amputation and 5 (3.2 %) died. In univariate analyses, the presence of critical limb ischemia, multilevel disease, age > 72 years, impaired renal function, and long lesions (> 65 mm) were significant determinants of the study endpoint. The anatomic location of the lesion, distal patency of treated artery below the ankle, cardiovascular risk factors or concomitant cardiovascular diseases, and the type of postinterventional antithrombotic treatment did not influence outcome. CONCLUSIONS: Below-knee interventions resulted in acceptable procedural mid-term results and high rates of amputation free survival. Multilevel disease, long lesions and impaired renal function were indicative of a worse outcome.

Rupture prone aneurysm of the inferior mesenteric artery complicated by mid aortic syndrome with occluded celiac and superior mesenteric arteries.

We present the case of a 45-year-old male patient with a large aneurysm of the inferior mesenteric artery complicated by mid aortic syndrome with occlusion of the celiac trunk and superior mesenteric artery. The vascular pathology was detected by CT imaging after presentation and hospitalization with symptoms of acute cholecystitis. After resolve of the acute symptoms, the aneurysm was resected and the proximal inferior mesenteric artery interponated with a reversed saphenous vein bypass graft. Besides presenting this case we review the literature concerning the rare descriptions of inferior mesenteric artery aneurysms.

DTI/DXI interferences with global coagulation tests in emergency hospital admissions - Results of the prospective Dresden NOAC Registry (NCT01588119).

BACKGROUND: Depending on test assays and the time of last DOAC intake, direct thrombin inhibitors (DTI) and direct FXa inhibitors (DXI) may or may not affect prothrombin time (PT), international normalized ratio (INR) or activated thromboplastin time (aPTT) but the clinical impact is unknown. METHODS: Using data from the Dresden NOAC Registry, we evaluated the impact of DOAC on first PT, INR or aPTT tests during emergency hospitalizations of DTI/DXI patients and the assay performance across 50 coagulation laboratories. RESULTS: In 724 emergency admissions (77 DTI; 647 DXI), 490 cases (67.7%) had a reported last DOAC intake within 12 h before blood sampling. INR and PT were elevated above the upper limit of normal (ULN) in >65% of all cases and aPTT was elevated in 45%. On the other hand, >30% of all cases had normal values of INR, PR and aPTT despite a DOAC intake within the last 12 h. Assay performance for detecting or ruling out therapeutic DOAC levels was highly variable and, overall, insufficient to guide clinical decisions. DOAC specific testing was performed in <10% of all cases. CONCLUSION: Many DOAC recipients present with elevated PT, INR or aPTT during emergency admissions but false negative values within 12 h of last intake as well as elevated values beyond 24 h after last DOAC intake are common. Both scenarios may result in clinical misinterpretation and, potentially, in patient harm, also because DOAC specific testing is rarely performed in emergency settings.

Impact of BMI on clinical outcomes of NOAC therapy in daily care - Results of the prospective Dresden NOAC Registry (NCT01588119).

Direct acting non-Vitamin K antagonist oral anticoagulants (NOAC) are characterized by a fixed dosing regimen. Despite the potential for relative underdosing due to large distribution volumes, dose adjustments for patients with high body mass index (BMI) are not recommended. Since efficacy and safety data in obese patients are scarce, we evaluated the impact of BMI on clinical outcomes in daily care patients treated with NOAC for stroke prevention in atrial fibrillation or venous thromboembolism. Using prospectively collected data from a non-interventional registry, cardiovascular (CV), major bleeding events (MB) and all-cause mortality were evaluated according to BMI classes. All outcome events were centrally adjudicated using standard scientific definitions. Between November 1st 2011 and December 31st 2016, 3432 patients were enrolled into the registry (61.3% rivaroxaban; 20% apixaban; 10.1% dabigatran, 8.6% edoxaban; mean follow-up 998.1 ±â€¯542.9 days; median 1004 days). With increasing BMI (range 13.7-57.2 kg/m2), the proportion of patients receiving standard (vs. reduced) NOAC dose increased from 64.7% (underweight) to 78.9% (obesity). Although obese patients had more cardiovascular risk factors compared to normal weight patients, on-treatment rates of clinical outcomes (CV, MB, all-cause-mortality) were lowest in overweight and obese patients. In a large set of real-life NOAC recipients we found no indication that high BMI is associated with inferior NOAC effectiveness or safety, which is in line with recent epidemiological data of a "BMI paradox" that indicates a somewhat protective effect of higher BMI regarding unfavourable outcomes also in patients receiving fixed dose NOAC anticoagulation without dose adjustment for higher BMI.

Improving the diagnostic management of upper extremity deep vein thrombosis.

Essentials The Constans score and D-dimer can rule out upper extremity deep vein thrombosis without imaging. We evaluated the performance of an extended Constans score and an age-adjusted D-dimer threshold. The extended Constans score did not increase the efficiency compared to the original score. Age-adjusted D-dimer testing safely increased the efficiency by 4%, but this needs validation. SUMMARY: Background Among patients with clinically suspected upper extremity deep vein thrombosis (UEDVT), a clinical decision rule based on the Constans score combined with D-dimer testing can safely rule out the diagnosis without imaging in approximately one-fifth of patients. Objectives To evaluate the performance of the original Constans score, an extended Constans score and an age-adjusted D-dimer positivity threshold. Methods Data of 406 patients with suspected UEDVT previously enrolled in a multinational diagnostic management study were used. The discriminatory performance, calibration and diagnostic accuracy of the Constans score were evaluated. The Constans score was extended by selecting clinical variables that may have incremental value in detecting UEDVT, conditional on the original Constans score items. The performance of the Constans rule was evaluated in combination with fixed and age-adjusted D-dimer thresholds. Results The original Constans score showed good discriminatory performance (c-statistic, 0.81; 95% confidence interval [CI], 0.76-0.85). An extended Constans score with five additional clinical items improved discriminatory performance and calibration, but this did not translate into a higher efficiency in avoiding imaging tests. Compared with a fixed threshold, age-adjusted D-dimer testing increased the proportion of patients for whom imaging and anticoagulation could be withheld from 21% to 25% (gain, 3.7%; 95% CI, 2.3-6.0%). Conclusions The Constans score has good discriminatory performance in the diagnosis of UEDVT. Age-adjusted D-dimer testing is likely to safely increase the efficiency of the diagnostic algorithm, but this approach needs prospective validation.

Current management strategies and long-term clinical outcomes of upper extremity venous thrombosis.

UNLABELLED: Essentials Few data exist on outcome of upper extremity deep and superficial vein thrombosis (UEDVT and UESVT). We followed 102 and 55 patients with UEDVT or UESVT, respectively, for a median of 3.5 years. Risk of recurrent venous thromboembolism was low in both diseases, and the mortality high. Postthrombotic symptoms were infrequent and cancer patients had a higher risk of recurrent VTE. SUMMARY: Background There is scant information on the optimal management and clinical outcome of deep and superficial vein thrombosis of the upper extremity (UEDVT and UESVT). Objectives To explore treatment strategies and the incidence of recurrent venous thromboembolism (VTE), mortality, postthrombotic symptoms, and bleeding in patients with UEDVT and UESVT and to assess the prognosis of cancer patients with UEDVT. Patients/methods Follow-up of patients with UEDVT or UESVT, who were enrolled previously in a diagnostic management study. Results We followed 102 and 55 patients with UEDVT and UESVT, respectively, both for a median of 3.5 years. Anticoagulant treatment was started in 100 patients with UEDVT (98%) and in 40 (73%) with UESVT. Nine patients with UEDVT (9%) developed recurrent VTE, 26 (26%) died, 6 (8%) of 72 patients had moderate postthrombotic symptoms, and 5 (5%) experienced major bleeding. One patient with UESVT had a recurrent VTE, 18 (33%) died, none had moderate postthrombotic symptoms, and none had major bleeding. Of the cancer patients with UEDVT, 18% had recurrent VTE vs. 7.5% in non-cancer patients (adjusted hazard ratio 2.2, 95%CI 0.6-8.2). The survival rate was 50% in cancer patients with UEDVT vs. 60% in those without (adjusted HR 0.8, 95%CI 0.4-1.4). Conclusions The risk of recurrent VTE was low in patients with UEDVT, and negligible for UESVT. Mortality was high for both diseases. Postthrombotic symptoms were infrequent and mild. Anticoagulant therapy of UEDVT carried a substantial risk of major bleeding. Cancer patients had a significant risk of recurrent VTE.

Of men and meals.

Rivaroxaban is increasingly used to treat patients with acute venous thromboembolism (VTE), a potentially life-threatening condition. Because absorption of rivaroxaban decreases from nearly 100% to 66% under fasting conditions, it is recommended that VTE patients take rivaroxaban with a meal. However, this recommendation is based on preclinical pharmacokinetic (PK) studies in healthy volunteers. So far, no clinical evidence is available to support this recommendation. We describe a case of a compliant young patient who developed recurrent pulmonary embolism during rivaroxaban treatment. PK studies provided evidence that malabsorption of rivaroxaban 20 mg due to irregular intake of meals during shift work was the leading cause of recurrent pulmonary embolism. When the patient was instructed to take rivaroxaban with a regular meal, peak plasma concentrations increased from 115 to 318 ng mL(-1) (+ 176%). Consequently, the importance of taking rivaroxaban with food may have a greater clinical relevance than data from preclinical PK studies suggest.

Phamacokinetics of rivaroxaban in adolescents.

BACKGROUND: The direct factor Xa inhibitor rivaroxaban is approved for venous thromboembolism (VTE) treatment in adults. However, in all phase-III trials children or adolescents have not been included. For under-aged VTE patients, current standard treatment consists of low molecular weight heparin or Vitamin K antagonists. Rivaroxaban could be an attractive alternative, however, no data on the pharmacokinetics (PK) of rivaroxaban in adolescents are currently available. PATIENT, METHODS: We report PK data for rivaroxaban derived from a girl (age:15 years), who presented three month after acute deep vein thrombosis, already receiving rivaroxaban therapy. In the steady state of rivaroxaban therapy (20 mg once daily), plasma levels at baseline, 3 and 6 hours after intake of rivaroxaban were measured to evaluate the pharmacokinetics and changes of global coagulation tests. RESULTS: At baseline, a very low trough level of only 9.9 ng/ml rivaroxaban was found. At 3 hours, a peak concentration of 137.76 ng/ml rivaroxaban was observed with a rapid decrease within 6 hours after drug intake, when plasma levels of 34.45 ng/ml were measured. The patients INR and aPTT values reacted correspondingly. CONCLUSION: Our data indicate that adolescents may exhibit lower peak and trough levels after rivaroxaban intake compared to adult patients, but seem to have similar PK curves during the elimination phase. While our case is the first published case of a successful VTE treatment in an under-aged patient, we strongly discourage the routine use of rivaroxaban in non-adult patients, until data from phase II and III trials are available.

Hospitalization for vitamin-K-antagonist-related bleeding: treatment patterns and outcome.

BACKGROUND: Bleeding complications are common side effects of vitamin-K antagonist (VKA) therapy. Data on the in-hospital management and outcomes of these bleeding events are scarce and information is mostly derived from trial cohorts. OBJECTIVES: The objective was to collect data on the management and clinical outcome of hospitalizations owing to VKA-related bleeding in real-world practice. PATIENTS AND METHODS: We performed a multicenter observational cohort study involving 21 secondary and tertiary care hospitals in the administrative district Dresden, Saxony, Germany throughout the year 2005. All consenting patients presenting with VKA-related bleeding complications were included. No exclusion criteria applied. Data were collected at admission, at discharge and at 90 days to evaluate resource consumption, length of hospital stay and risk factors for in-hospital- and 3-month mortality. RESULTS: Two hundred and ninety patients were included (median age 74 years; 50.7% male). The main indications for VKA therapy were atrial fibrillation (63.4%), prior thromboembolism (18.6%) and mechanical heart valves (11.4%), and most common bleeding localizations were large hematoma (23.1%), upper gastrointestinal (GI) tract (17.9%) and intracranial bleeding (14.1%). On hospital admission, the median International Normalized Ratio (INR) was 3.0 (range 0.9-12.5, interquartile range [IQR] 2.1-3.9). In-hospital mortality was 7.6% with impaired renal function as the most relevant risk factor. At 90 days mortality was 14.1% and 15.3% of survivors were help-dependent. CONCLUSIONS: VKA-related bleeding leading to hospitalization is associated with long hospitalization, relevant resource utilization, high mortality or persistent sequlae. Patient-related factors such as impaired renal function, chronic cardiac or pulmonary disease and dementia are predictive of in-hospital and 3-month mortality.

Efficacy and safety of rivaroxaban or fondaparinux thromboprophylaxis in major orthopedic surgery: findings from the ORTHO-TEP registry.

BACKGROUND: Thromboprophylaxis with rivaroxaban (R) is superior to enoxaparin in patients undergoing major orthopedic surgery (MOS). However, rivaroxaban has never been directly compared with fondaparinux (F), which also shows superior efficacy over enoxaparin. The clinical impact of switching from fondaparinux to rivaroxaban thromboprophylaxis is unclear. OBJECTIVES: To evaluate the efficacy and safety of rivaroxaban or fondaparinux thromboprophylaxis in unselected patients undergoing MOS. PATIENTS/METHODS: This is a monocentric, retrospective cohort study in 5061 consecutive patients undergoing MOS at our centre, comparing rates of symptomatic VTE, bleeding and surgical complications, length of hospital stay and risk factors for VTE. RESULTS: Rates of symptomatic VTE were 5.6% (F) and 2.1% (R; P < 0.001), with rates for distal DVT being 3.9 vs. 1.1% (P < 0.001). Rates of major VTE were numerically higher with fondaparinux (1.8 vs. 1.1%), but not statistically significant. Rates of severe bleeding (bleeding leading to surgical revision or death, occurring in a critical site, or transfusion of at least two units of packed red blood cells) were statistically lower with rivaroxaban compared with fondaparinux (2.9 vs. 4.9%; P = 0.010). The mean length of hospital stay was significantly shorter in the rivaroxaban group (8.3 days, 95% CI 8.1-8.5 vs. 9.3 days, 9.1-9.5; P < 0.001). CONCLUSION: Based on an indirect comparison of two consecutive cohorts, our data suggest that thromboprophylaxis with rivaroxaban is associated with less VTE and bleeding events than fondaparinux in unselected patients undergoing MOS. Prospective comparisons are warranted to confirm our findings.

[Risk of bleeding and haemorrhagic complication with rivaroxaban--periprocedural management of haemostasis]. / Blutungsrisiko und Blutungsnotfälle unter Rivaroxaban. Periinterventionelles Hämostasemanagement.

UNLABELLED: 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.

External and internal validity of open label or double-blind trials in oral anticoagulation: better, worse or just different?

Currently, few topics in the field of anticoagulant therapy are as intensely discussed as the question: which is the best new oral anticoagulant? The most advanced substances in this field are the oral direct factor Xa-inhibitors rivaroxaban, apixaban and edoxaban and the oral direct thrombin inhibitor dabigatran. All of these substances are currently being tested in very similar phase III trials or are in the process of approval. In these trials, open-label or double-blind double-dummy designs are being used to evaluate the efficacy and safety in prevention and treatment of venous thromboembolism or stroke prevention in atrial fibrillation in several thousands of patients. As a consequence, an intense discussion of the advantages and disadvantages of open-label or double-blind trials is currently under way and interpretation of trial results is often focused on this matter. In general, a blinded trial is regarded as being less subject to bias than an open trial because it minimizes the impact of knowledge of treatment allocation on post-randomized treatment decisions and on reporting of outcomes. However, a blinded trial is not always feasible. Thus, in some respects, the two trial designs offer complementary strengths and weaknesses. This review addresses the risks of bias for internal and external validity of open-label and double-blind anticoagulation trials to help to objectify this debate.