Isolated Distal Deep Vein Thrombosis: Perspectives from the GARFIELD-VTE Registry

Isolated distal deep vein thrombosis (IDDVT) represents up to half of all lower limb DVT. This study investigated treatment patterns and outcomes in 2,145 patients with IDDVT in comparison with those with proximal DVT (PDVT; n = 3,846) and pulmonary embolism (PE; n = 4,097) enrolled in the GARFIELD-VTE registry. IDDVT patients were more likely to have recently undergone surgery (14.6%) or experienced leg trauma (13.2%) than PDVT patients (11.0 and 8.7%, respectively) and PE patients (12.7 and 4.5%, respectively). Compared with IDDVT, patients with PDVT or PE were more likely to have active cancer (7.2% vs. 9.9% and 10.3%). However, influence of provoking factors on risk of recurrence in IDDVT remains controversial. Nearly all patients (IDDVT, PDVT, and PE) were given anticoagulant therapy. In IDDVT, PDVT, and PE groups the proportion of patients receiving anticoagulant therapy was 61.4, 73.9, and 81.1% at 6 months and 45.8, 54.7, and 61.9% at 12 months. Over 12 months, the incidence of all-cause mortality, cancer, and recurrence was significantly lower in IDDVT patients than PDVT patients (hazard ratio [HR], 0.61 [95% confidence interval [CI], 0.48–0.77]; sub-HR [sHR], 0.60 [95% CI, 0.39–0.93]; and sHR, 0.76 [95% CI, 0.60–0.97]). Likewise, risk of death and incident cancer was significantly (both p < 0.05) lower in patients with IDDVT compared with PE. This study reveals a global trend that most IDDVT patients as well as those with PDVT and PE are given anticoagulant therapy, in many cases for at least 12 months.

Long term risk of symptomatic recurrent venous thromboembolism after discontinuation of anticoagulant treatment for first unprovoked venous thromboembolism event: systematic review and meta-analysis

OBJECTIVES

To determine the rate of a first recurrent venous thromboembolism (VTE) event after discontinuation of anticoagulant treatment in patients with a first episode of unprovoked VTE, and the cumulative incidence for recurrent VTE up to 10 years.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Medline, Embase, and the Cochrane Central Register of Controlled Trials (from inception to 15 March 2019).

STUDY SELECTION

Randomised controlled trials and prospective cohort studies reporting symptomatic recurrent VTE after discontinuation of anticoagulant treatment in patients with a first unprovoked VTE event who had completed at least three months of treatment.

DATA EXTRACTION AND SYNTHESIS

Two investigators independently screened studies, extracted data, and appraised risk of bias. Data clarifications were sought from authors of eligible studies. Recurrent VTE events and person years of follow-up after discontinuation of anticoagulant treatment were used to calculate rates for individual studies, and data were pooled using random effects meta-analysis. Sex and site of initial VTE were investigated as potential sources of between study heterogeneity.

RESULTS

18 studies involving 7515 patients were included in the analysis. The pooled rate of recurrent VTE per 100 person years after discontinuation of anticoagulant treatment was 10.3 events (95% confidence interval 8.6 to 12.1) in the first year, 6.3 (5.1 to 7.7) in the second year, 3.8 events/year (95% confidence interval 3.2 to 4.5) in years 3-5, and 3.1 events/year (1.7 to 4.9) in years 6-10. The cumulative incidence for recurrent VTE was 16% (95% confidence interval 13% to 19%) at 2 years, 25% (21% to 29%) at 5 years, and 36% (28% to 45%) at 10 years. The pooled rate of recurrent VTE per 100 person years in the first year was 11.9 events (9.6 to 14.4) for men and 8.9 events (6.8 to 11.3) for women, with a cumulative incidence for recurrent VTE of 41% (28% to 56%) and 29% (20% to 38%), respectively, at 10 years. Compared to patients with isolated pulmonary embolism, the rate of recurrent VTE was higher in patients with proximal deep vein thrombosis (rate ratio 1.4, 95% confidence interval 1.1 to 1.7) and in patients with pulmonary embolism plus deep vein thrombosis (1.5, 1.1 to 1.9). In patients with distal deep vein thrombosis, the pooled rate of recurrent VTE per 100 person years was 1.9 events (95% confidence interval 0.5 to 4.3) in the first year after anticoagulation had stopped. The case fatality rate for recurrent VTE was 4% (95% confidence interval 2% to 6%).

CONCLUSIONS

In patients with a first episode of unprovoked VTE who completed at least three months of anticoagulant treatment, the risk of recurrent VTE was 10% in the first year after treatment, 16% at two years, 25% at five years, and 36% at 10 years, with 4% of recurrent VTE events resulting in death. These estimates should inform clinical practice guidelines, enhance confidence in counselling patients of their prognosis, and help guide decision making about long term management of unprovoked VTE.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017056309.

Upper Extremity DVT versus Lower Extremity DVT: Perspectives from the GARFIELD-VTE Registry

Upper extremity deep vein thrombosis (UEDVT) is less common than lower extremity DVT (LEDVT) and consequently less well characterized. This study compared clinical characteristics and 1-year outcomes between 438 UEDVT patients and 7,602 LEDVT patients recruited in the GARFIELD-VTE registry. UEDVT patients were significantly more likely to have a central venous catheter than those with LEDVT (11.5% vs. 0.5%; p < 0.0001), and had a higher rate of active cancer (16.2%) or recent hospitalization (19.4%) compared with LEDVT patients (8.7% and 11.2%, respectively). Nearly all patients with UEDVT and LEDVT were initiated on anticoagulant therapy, which was a direct oral anticoagulant in one-third individuals in both groups. At 3, 6, and 12 months, the proportion of UEDVT and LEDVT patients who were receiving anticoagulant therapy was 82.6 and 87.4%, 66.0 and 72.6%, and 45.7 and 54.6%, respectively. In the UEDVT and LEDVT groups, VTE recurrence rate was 4.0 (95% confidence interval [CI], 2.4–6.7) and 5.5 (95% CI, 4.9–6.1) per 100 person-years, respectively; major bleed was noted in 1.3 (95% CI, 0.6–3.2) and 1.6 (95% CI, 1.3–1.9) per 100 person-years and all-cause mortality in 9.7 (95% CI, 7.1–13.4) and 6.7 (95% CI, 6.1–7.3) per 100 person-years, respectively. Hence, risk of recurrence was similar in the two groups whereas all-cause mortality was significantly higher in the UEDVT group than the LEDVT group (p = 0.0338). This latter finding was likely due to the high prevalence of cancer in the UEDVT group.

Laboratory Monitoring of Non-Vitamin K Antagonist Oral Anticoagulant Use in Patients With Atrial Fibrillation: A Review

Importance

The non-vitamin K antagonist oral anticoagulants (NOACs) apixaban, dabigatran, edoxaban, and rivaroxaban are administered in fixed doses without anticoagulant monitoring. Randomized trials show that unmonitored NOAC therapy is at least as effective as and safer than dose-adjusted warfarin for stroke prevention in patients with nonvalvular atrial fibrillation. Subgroup analyses indicate that plasma drug levels or anticoagulant activity of the NOACs predict stroke and bleeding. This review examines the historical basis for anticoagulant monitoring, discusses methods to measure and interpret drug levels, and critically assesses the role of routine laboratory monitoring in the management of NOAC therapy.

Observations

The predictable anticoagulant response of NOACs has provided the pharmacological basis for their administration in fixed doses without routine coagulation monitoring. Although it is possible to accurately measure NOAC drug levels, within-patient variability complicates interpretation of these results. Furthermore, patient characteristics, such as age and renal function, confound the association between NOAC drug levels and clinical outcomes. Information is lacking on the optimal drug level in particular patient groups (eg, elderly, the renally impaired, and those with high bleeding risk), the appropriate dose adjustment to achieve expected levels, and whether routine laboratory monitoring and dose adjustment will improve clinical outcomes. A benefit of a management strategy that incorporates routine therapeutic drug monitoring and dose adjustment over current standard-of-care metrics without such monitoring remains unproven.

Conclusions and Relevance

Robust evidence from patients with atrial fibrillation randomized to NOACs or warfarin demonstrates that unmonitored NOAC therapy is at least as effective and safe as monitored warfarin, with lower rates of intracranial hemorrhage and reduced mortality. Further research is required to determine whether routine laboratory monitoring might provide a net benefit for patients. Until such data are available, clinicians should continue to prescribe NOACs in fixed doses without routine monitoring.

Antibody-Based Ticagrelor Reversal Agent in Healthy Volunteers

BACKGROUND

Ticagrelor is an oral P2Y₁₂ inhibitor that is used with aspirin to reduce the risk of ischemic events among patients with acute coronary syndromes or previous myocardial infarction. Spontaneous major bleeding and bleeding associated with urgent invasive procedures are concerns with ticagrelor, as with other antiplatelet drugs. The antiplatelet effects of ticagrelor cannot be reversed with platelet transfusion. A rapid-acting reversal agent would be useful.

METHODS

In this randomized, double-blind, placebo-controlled, phase 1 trial, we evaluated intravenous PB2452, a monoclonal antibody fragment that binds ticagrelor with high affinity, as a ticagrelor reversal agent. We assessed platelet function in healthy volunteers before and after 48 hours of ticagrelor pretreatment and again after the administration of PB2452 or placebo. Platelet function was assessed with the use of light transmission aggregometry, a point-of-care P2Y₁₂ platelet-reactivity test, and a vasodilator-stimulated phosphoprotein assay.

RESULTS

Of the 64 volunteers who underwent randomization, 48 were assigned to receive PB2452 and 16 to receive placebo. After 48 hours of ticagrelor pretreatment, platelet aggregation was suppressed by approximately 80%. PB2452 administered as an initial intravenous bolus followed by a prolonged infusion (8, 12, or 16 hours) was associated with a significantly greater increase in platelet function than placebo, as measured by multiple assays. Ticagrelor reversal occurred within 5 minutes after the initiation of PB2452 and was sustained for more than 20 hours (P<0.001 after Bonferroni adjustment across all time points for all assays). There was no evidence of a rebound in platelet activity after drug cessation. Adverse events related to the trial drug were limited mainly to issues involving the infusion site.

CONCLUSIONS

In healthy volunteers, the administration of PB2452, a specific reversal agent for ticagrelor, provided immediate and sustained reversal of the antiplatelet effects of ticagrelor, as measured by multiple assays. (Funded by PhaseBio Pharmaceuticals; ClinicalTrials.gov number, NCT03492385.).

Factor XIII Prevents Pulmonary Emboli in Mice by Stabilizing Deep Vein Thrombi

BACKGROUND

 Deep vein thrombosis (DVT) can lead to pulmonary embolism (PE), but the mechanisms responsible for this progression are unknown. Previously, we showed that inhibition of thrombin-mediated activation of factor (F) XIII promotes venous thrombus stability in a murine model.

AIM

 In this study, we investigate the consequence of attenuating fibrinolysis, using FXIII, α₂-antiplasmin (α₂-AP) or ε-aminocaproic acid (EACA) supplementation, on clot lysis and venous thrombus stability using the same mouse model.

METHODS

 In vitro plasma clot lysis assay shows that EACA and α₂-AP but not FXIII, inhibit fibrinolysis. Ferric chloride induced thrombi in the femoral vein of mice. After thrombus formation, mice received saline, EACA, α₂-AP or FXIII, with or without dalteparin or dabigatran. Thrombus sizes and embolization over 2 hours were visualized using intravital videomicroscopy. Lungs were sectioned to quantify emboli presence via histology.

RESULTS

 The change in thrombus size over time was significantly greater after EACA treatment, but not FXIII or α₂-AP supplementation, compared with saline. α₂-AP-supplementation did not alter thrombus stability. Thrombi were more stable following EACA treatment and FXIII supplementation as evidenced by less embolic events and PE burden, even when they were anticoagulated with either dalteparin or dabigatran.

CONCLUSION

 FXIII supplementation stabilized venous thrombi, even in the presence of anticoagulants, and did not alter thrombus size. Supplemental FXIII may be useful to stabilize DVT and be an alternative adjunctive treatment to minimize PE, even when anticoagulants are used.

Incident Atrial Fibrillation, Dementia and the Role of Anticoagulation: A Population-Based Cohort Study

INTRODUCTION

 Atrial fibrillation (AF) is associated with dementia. Anticoagulation may modify this relationship, but it is unclear if this is due to stroke reduction alone.

METHODS

 Age- and sex-matched individuals from the U.K. Clinical Practice Research Datalink (2008-2016) with and without an incident diagnosis of AF were followed for a new dementia diagnosis. We estimated adjusted hazard ratios (aHRs) for incident dementia diagnosis in the AF cohort, overall and stratified by anticoagulation status, using the matched non-AF cohorts as reference. We performed a sensitivity analysis excluding individuals with stroke/transient ischaemic attack (TIA) before the observation period.

RESULTS

 Over 193,082 person-years (mean follow-up 25.7 ± 0.1 months), 347/15,276 AF (2.3%) and 1,085/76,096 non-AF (1.4%) were newly diagnosed with dementia (aHR, 1.31, 95% confidence interval, 1.15-1.49). The AF group had more co-morbidity and higher rates of dementia, both with and without anticoagulation, than non-AF. When those with history of stroke/ TIA before the observation period were excluded and those with incident stroke/TIA during the observation period were censored, AF individuals not on anticoagulation had significantly higher rates of dementia compared with non-AF, aHR 1.30 (1.06-1.58).

CONCLUSION

 Our findings support the hypothesis that AF is a distinct risk factor for dementia, independent of stroke/TIA and other vascular risk factors. In those without stroke/TIA, risk of dementia is increased only in those who are not on anticoagulation, suggesting anticoagulation is protective presumably through reduction of sub-clinical embolic events. Further prospective research is needed to better ascertain the role of anticoagulation amongst targeted therapeutic strategies to reduce cognitive decline in AF.

Long-Term Management of Venous Thromboembolism: Lessons from EINSTEIN CHOICE and Other Extension Trials

Many patients with venous thromboembolism (VTE) are at risk of recurrence if anticoagulant therapy is stopped. Whereas 3 months of anticoagulation treatment is sufficient for patients with VTE provoked by major surgery or trauma, in many cases a longer course is needed. Extended therapy with vitamin K antagonists (VKAs) requires frequent coagulation monitoring and dose adjustments to ensure that the international normalized ratio (INR) remains within the therapeutic range; furthermore, there is a risk of major bleeding even if a therapeutic INR is maintained. Therefore, more convenient and safer anticoagulants are needed.The non-VKA oral anticoagulants (NOACs)-apixaban, dabigatran, edoxaban and rivaroxaban-simplify extended therapy because they can be given in fixed doses without routine coagulation monitoring. Randomized clinical trials have demonstrated the efficacy and safety of NOACs for extended VTE treatment, but bleeding remains a concern. Patients and physicians may, therefore, be reluctant to continue anticoagulation beyond 3 to 6 months except in patients at high risk of recurrence. Acetylsalicylic acid (ASA) is often prescribed instead of an anticoagulant because of its perceived lower risk of bleeding; however, the recent EINSTEIN CHOICE trial demonstrated that once-daily rivaroxaban at a dose of either 20 or 10 mg reduced the risk of recurrent VTE by 70% compared with ASA without significantly increasing the risk of bleeding. In this review, we discuss the EINSTEIN CHOICE trial in the context of previous trials for extended VTE treatment and examine some of the lessons that can be applied to clinical practice.

Rivaroxaban for prevention and treatment of venous thromboembolism

Until recently, heparins and vitamin K antagonists (VKAs) were the cornerstones for prevention and treatment of venous thromboembolism (VTE). This situation changed with the introduction of the direct oral anticoagulants, which are now replacing low-molecular-weight heparin for thromboprophylaxis after elective hip or knee arthroplasty and VKAs for VTE treatment. Rivaroxaban, an oral factor Xa inhibitor, was the first direct oral anticoagulant licensed for VTE prevention and treatment. This paper provides the rationale for factor Xa as a target for anticoagulants, describes the development of rivaroxaban, reviews its pharmacological profile, discusses the clinical trials with rivaroxaban for VTE prevention and treatment and highlights areas of uncertainty.

Characteristics and Outcomes in Patients with Venous Thromboembolism Taking Concomitant Anti-Platelet Agents and Anticoagulants in the AMPLIFY Trial

The double-blind, randomized, AMPLIFY trial compared 6 months' treatment with apixaban (10 mg twice daily for 7 days and 5 mg twice daily thereafter) versus conventional treatment (subcutaneous enoxaparin [1 mg/kg twice daily for ≥ 5 days] overlapped and followed by warfarin [international normalized ratio = 2.0-3.0]) in patients with acute venous thromboembolism (VTE). This post hoc analysis of AMPLIFY compared outcomes among those taking or not taking concomitant anti-platelet therapy. The primary efficacy outcome was recurrent VTE or VTE-related death; the principal safety outcome was major bleeding. Of 5,365 (apixaban, n = 2,676; enoxaparin/warfarin, n = 2,689) randomized patients, 813 (apixaban, n = 402 [15%]; enoxaparin/warfarin, n = 411 [15%]) took concomitant anti-platelet therapy, of which 92% consisted of low-dose aspirin. Rates of VTE or VTE-related death were similar whether or not anti-platelet agents were taken (apixaban: 3.6 and 2.0%; enoxaparin/warfarin: 3.0 and 2.6%; anti-platelet use: relative risk [RR], 1.23; 95% confidence interval [CI], 0.58-2.62; no anti-platelet use: RR, 0.77; 95% CI, 0.52-1.13); interaction p-value = 0.299. Major bleeding rates were threefold higher in those taking versus those not taking anti-platelet agents (apixaban: 1.2 and 0.4%; enoxaparin/warfarin: 4.1 and 1.4%; anti-platelet use: RR, 0.30; 95% CI, 0.11-0.81; no anti-platelet use: RR, 0.31; 95% CI, 0.15-0.63); interaction p-value = 0.924. Concomitant anti-platelet therapy produced a proportionally similar increase in major bleeding in patients randomized to apixaban or conventional therapy, but there were fewer major bleeds with apixaban. Therefore, the overall safety of apixaban over conventional therapy was maintained in patients receiving anti-platelet therapy. Clinicaltrials.gov: NCT00643201.

Advances in Antithrombotic Therapy

Thrombosis remains a major cause of morbidity and mortality. Consequently, advances in antithrombotic therapy are needed to reduce the disease burden. This article focuses on 2 such advances. First, the prevention of atherothrombosis in patients with coronary or peripheral artery disease, which has been enhanced by the finding that the combination of low-dose rivaroxaban plus aspirin is superior to aspirin alone for prevention of recurrent ischemic events. However, this benefit comes at the cost of increased bleeding albeit not fatal bleeding. To overcome this problem, the second advance is the identification of factor XI as a target for new anticoagulants that are potentially safer than those currently available.

Characteristics and Management of Patients with Venous Thromboembolism: The GARFIELD-VTE Registry

BACKGROUND

 Management of venous thromboembolism (VTE), encompassing both deep vein thrombosis (DVT) and pulmonary embolism (PE), varies worldwide.

METHODS

 The Global Anticoagulant Registry in the FIELD - Venous Thromboembolism (GARFIELD-VTE) is a prospective, observational study of 10,685 patients with objectively diagnosed VTE recruited from May 2014 to January 2017 at 417 sites in 28 countries. All patients are followed for at least 3 years. We describe the baseline characteristics of the study population and their management within 30 days of diagnosis.

RESULTS

 The median age was 60.2 years; 50.4% were male; 61.7% had DVT and 38.3% had PE ± DVT; and 32.3% were obese (body mass index ≥ 30 kg/m²). The most common risk factors were surgery (12.5%), hospitalization (12.0%) and trauma to the lower limbs (7.8%). At the time of VTE diagnosis, 10.1% had active cancer and 5.7% were chronically immobilized. Treatment for VTE was anticoagulant (AC) therapy alone in 90.9% of patients; 5.1% received thrombolytic and/or surgical/mechanical therapy ± AC and 4.0% received no therapy. Pre-diagnosis, 12.8% received AC therapy alone and 0.2% received thrombolytic and/or surgical/mechanical therapy ± AC. After diagnosis, parenteral AC therapy alone was administered in 17.6% of patients, and it was followed by a direct oral AC (DOAC) in 16.4% or a vitamin K antagonist (VKA) in 26.8%. DOACs alone were prescribed to 32.3% of patients, while 5.9% received VKA alone.

CONCLUSION

 The initial findings from this global registry highlight the heterogeneity in characteristics and management of VTE patients. Prospective follow-up will reveal the impact of this heterogeneity on outcomes.

Lubricant-Infused Surfaces with Built-In Functional Biomolecules Exhibit Simultaneous Repellency and Tunable Cell Adhesion

Lubricant-infused omniphobic surfaces have exhibited outstanding effectiveness in inhibiting nonspecific adhesion and attenuating superimposed clot formation compared with other coated surfaces. However, such surfaces blindly thwart adhesion, which is troublesome for applications that rely on targeted adhesion. Here we introduce a new class of lubricant-infused surfaces that offer tunable bioactivity together with omniphobic properties by integrating biofunctional domains into the lubricant-infused layer. These novel surfaces promote targeted binding of desired species while simultaneously preventing nonspecific adhesion. To develop these surfaces, mixed self-assembled monolayers (SAMs) of aminosilanes and fluorosilanes were generated. Aminosilanes were utilized as coupling molecules for immobilizing capture ligands, and nonspecific adhesion of cells and proteins was prevented by infiltrating the fluorosilane molecules with a thin layer of a biocompatible fluorocarbon-based lubricant, thus generating biofunctional lubricant-infused surfaces. This method yields surfaces that (a) exhibit highly tunable binding of anti-CD34 and anti-CD144 antibodies and adhesion of endothelial cells, while repelling nonspecific adhesion of undesirable proteins and cells not only in buffer but also in human plasma or human whole blood, and (b) attenuate blood clot formation. Therefore, this straightforward and simple method creates biofunctional, nonsticky surfaces that can be used to optimize the performance of devices such as biomedical implants, extracorporeal circuits, and biosensors.

Fibrinolysis: strategies to enhance the treatment of acute ischemic stroke

Stroke is a major cause of disability worldwide, and is the second leading cause of death after ischemic heart disease. Until recently, tissue-type plasminogen activator (t-PA) was the only treatment for acute ischemic stroke. If administered within 4.5 h of symptom onset, t-PA improves the outcome in stroke patients. Mechanical thrombectomy is now the preferred treatment for patients with acute ischemic stroke resulting from a large-artery occlusion in the anterior circulation. However, the widespread use of mechanical thrombectomy is limited by two factors. First, only ⁓ 10% of patients with acute ischemic stroke have a proximal large-artery occlusion in the anterior circulation and present early enough to undergo mechanical thrombectomy within 6 h; an additional 9-10% of patients presenting within the 6-24-h time window may also qualify for the procedure. Second, not all stroke centers have the resources or expertise to perform mechanical thrombectomy. Nonetheless, patients who present to hospitals where thrombectomy is not an option can receive intravenous t-PA, and those with qualifying anterior circulation strokes can then be transferred to tertiary stroke centers where thrombectomy is available. Therefore, despite the advances afforded by mechanical thrombectomy, there remains a need for treatments that improve the efficacy and safety of thrombolytic therapy. In this review, we discuss: (i) current treatment options for acute ischemic stroke; (ii) the mechanism of action of fibrinolytic agents; and (iii) potential strategies to manipulate the fibrinolytic system to promote endogenous fibrinolysis or to enhance the efficacy of fibrinolytic therapy.

Rivaroxaban for Thromboprophylaxis after Hospitalization for Medical Illness

BACKGROUND

Patients who are hospitalized for medical illness remain at risk for venous thromboembolism after discharge, but the role of extended thromboprophylaxis in the treatment of such patients is a subject of controversy.

METHODS

In this randomized, double-blind trial, medically ill patients who were at increased risk for venous thromboembolism on the basis of a modified International Medical Prevention Registry on Venous Thromboembolism (IMPROVE) score of 4 or higher (scores range from 0 to 10, with higher scores indicating a higher risk of venous thromboembolism) or a score of 2 or 3 plus a plasma d-dimer level of more than twice the upper limit of the normal range (defined according to local laboratory criteria) were assigned at hospital discharge to either once-daily rivaroxaban at a dose of 10 mg (with the dose adjusted for renal insufficiency) or placebo for 45 days. The primary efficacy outcome was a composite of symptomatic venous thromboembolism or death due to venous thromboembolism. The principal safety outcome was major bleeding.

RESULTS

Of the 12,024 patients who underwent randomization, 12,019 were included in the intention-to-treat analysis. The primary efficacy outcome occurred in 50 of 6007 patients (0.83%) who were given rivaroxaban and in 66 of 6012 patients (1.10%) who were given placebo (hazard ratio, 0.76; 95% confidence interval [CI], 0.52 to 1.09; P=0.14). The prespecified secondary outcome of symptomatic nonfatal venous thromboembolism occurred in 0.18% of patients in the rivaroxaban group and 0.42% of patients in the placebo group (hazard ratio, 0.44; 95% CI, 0.22 to 0.89). Major bleeding occurred in 17 of 5982 patients (0.28%) in the rivaroxaban group and in 9 of 5980 patients (0.15%) in the placebo group (hazard ratio, 1.88; 95% CI, 0.84 to 4.23).

CONCLUSIONS

Rivaroxaban, given to medical patients for 45 days after hospital discharge, was not associated with a significantly lower risk of symptomatic venous thromboembolism and death due to venous thromboembolism than placebo. The incidence of major bleeding was low. (Funded by Janssen Research and Development; MARINER ClinicalTrials.gov number, NCT02111564 .).

Immunologic Identification of the Cleavage Products from the Aα- and Bβ-Chains in the Early Stages of Plasmin Digestion of Fibrinogen

Fragment X components (Mr 225,000 to 333,000) were distinguished on sodium dodecyl sulfate polyacrylamide gels. Western blotting with monoclonal antibodies to Aα-chain segments demonstrated that the Aα-chains of fibrinogen and the largest fragment X components (Mr 285,000-340,000) contained both Aα 259-276 and Aα 540-554. Fragment X components of Mr 270.000-285,000 contained Aα 259-276 but lacked Aα 540-554, whereas the smallest fragment X components (Mr 225.000-270,000) contained neither Aα 540-554 nor Aα 259-276. Studies of the small peptides generated during fragment X formation complemented the studies of the large molecules, by demonstrating peptides containing both Aα 259-276 and Aα 540-554 (Mr 41,600-41,800 and Mr 38,700-38,900), peptides containing Aα 540-554 but not Aα 259-276 (Mr 20,500-21,000 and Mr 17,300-17,500) and peptides containing only Aα 259-276 (Mr 23,600-24,000 and Mr 20,500-21,000). Cleavage of Bβ 1-42 from the amino terminal ends of the Bβ-chains, measured with a specific radioimmunoassay, was linear until 1.6 moles per mole of fibrinogen had been relased, and coincided with loss of the central and carboxy terminal Aα-chain regions, i. e. Aα 259-276 and Aα 540-554. Based on present and previously reported data, a model is proposed for the evolution of the heterogenous group of fragment X derivatives from fibrinogen with the simultaneous release of small peptides. Features of this model include

1. asymmetric cleavage of the fibrinogen dimer and

2. proteolyses of several different bonds occurring simultaneously but at distinct rates.

The prothrombin time does not predict the risk of recurrent venous thromboembolism or major bleeding in rivaroxaban-treated patients

INTRODUCTION

For treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE), rivaroxaban is given in fixed doses without routine coagulation monitoring.

PATIENTS AND METHODS

To determine whether monitoring would enhance its benefit-risk profile, we examined whether peak and trough prothrombin time (PT) values measured in 3797 rivaroxaban-treated patients included in the EINSTEIN DVT and PE studies correlated with subsequent recurrent VTE and major bleeding. In addition, we examined the stability of PT values over time and the impact of clinical variables on PT values.

RESULTS

The mean peak PT values at months 3 and 6 or 12 were 21.9 ± 5 and 21.7 ± 6.0 s, respectively, while the mean trough PT values at months 2 and 6 were 15.1 ± 5.1 and 15.3 ± 2.9 s, respectively. Although peak and through PT values were higher in females, and with older age, frailty, active cancer, low body weight, impaired renal function and use of moderate to strong inhibitors of CYP3A4 and/or P-glycoprotein, and were lower in patients taking strong CYP 3A4 inducers, the differences were small and results were overlapping. Neither peak nor trough PT values correlated with recurrent VTE or major bleeding.

CONCLUSIONS

PT monitoring is unlikely to improve the benefit-risk profile of rivaroxaban in patients with DVT or PE. The study was registered at www.clinicaltrials.gov as #NCT00440193 (EINSTEIN-DVT) and #NCT00439777 (EINSTEIN-PE).

Standard and Low Molecular Weight Heparin Have no Effect on Tissue Plasminogen Activator Induced Plasma Clot Lysis or Fibrinogenolysis

Although heparin is often given as an adjunct to tissue plasminogen activator (t-PA), the effect of heparin on t-PA induced fibrin(ogen)olysis is controversial. To address this controversy, we examined the effects of standard and low molecular weight heparin (enoxaparine) on both t-PA induced clot lysis and t-PA mediated fibrinogenolysis in a human plasma system. Accordingly, 125I-labeled fibrin clots were incubated in t-PA containing citrated plasma in the presence or absence of these glycosaminoglycans, and the extent of thrombolysis was determined by measuring residual radioactivity of the clots, while Bβ1–42 levels were used as a specific index of fibrinogenolysis. Over a wide range of t-PA concentrations (0.1 to 1.6 μg/ml), neither heparin nor enoxaparine influences either t-PA induced clot lysis or t-PA mediated Bβ1–42 generation. These findings suggest that either agent could be used as an adjunct to t-PA without compromising either the thrombolytic potential of t-PA or its clotselectivity

More Effective Suppression of Hemostatic System Activation in Patients Undergoing Cardiac Surgery by Heparin Dosing Based on Heparin Blood Concentrations rather than ACT

This study was designed to determine whether the maintenance of higher than usual patient-specific heparin concentrations during cardiopulmonary bypass (CPB) was associated with more effective suppression of hemostasis system activation.

Thirty-one patients scheduled for repeat cardiac sugery or combined procedures (i.e., coronary revascularization + valve repair/replacement) were consented and enrolled in this study. All patients received porcine heparin and protamine and were randomly assigned to monitoring of anticoagulation by either celite ACT alone (Control, n = 16) or by kaolin ACT combined with on-site measurements of whole blood heparin concentration (Intervention, n = 15). Blood specimens collected before administration of heparin, before weaning from CPB and after administration of protamine were analyzed with a battery of coagulation assays.

Patients in the intervention cohort received appreciably greater heparin doses than control patients, resulting in higher anti-Xa heparin levels at the end of CPB. Fibrinopeptide A and D-dimer levels were higher in the control group before discontinuation of CPB. Percent decrease during CPB were greater in the control group for factors V and VIII, fibrinogen and antithrombin III. Percent decrease in complement 3 was greater in the control group after protamine and bleeding times measured in the Intensive Care Unit were significantly more prolonged in this group.

Maintenance of higher patient-specific heparin concentrations during CPB more effectively suppresses excessive hemostatic system activation than do standard heparin doses chosen based on measurement of ACT. These findings may explain, at least in part, the significant reduction in perioperative blood loss and blood product use when higher heparin concentrations are maintained.

Benefits and risks of extended treatment of venous thromboembolism with rivaroxaban or with aspirin

BACKGROUND

Full- or lower-dose anticoagulant therapy or aspirin can be used for extended therapy in patients with venous thromboembolism (VTE), but information on their relative benefit-risk profiles is limited.

METHODS

Data from the EINSTEIN-CHOICE trial were used to compare the benefit-risk profiles of extended treatment with rivaroxaban (20 or 10 mg once daily) and aspirin (100 mg once daily) in VTE patients who had completed 6 to 12 months of anticoagulation therapy. One-year cumulative incidences of recurrent VTE and major bleeding were estimated and benefits and risks were calculated by determining the between group differences in a hypothetical population of 10,000 VTE patients treated for 1 year.

FINDINGS

A total of 1107 patients were treated with 20 mg of rivaroxaban, 1127 with 10 mg of rivaroxaban, and 1131 with aspirin. The cumulative incidences of recurrent VTE in the rivaroxaban 20-mg, rivaroxaban 10-mg and aspirin groups were 1.9%, 1.6%, and 5.0%, respectively, whereas the cumulative incidences of major bleeding were 0.7%, 0.4% and 0.5%, respectively. The incidences of the combined outcome of recurrent VTE and major bleeding were 2.8% and 3.4% lower in the rivaroxaban 20-mg and 10-mg groups than in the aspirin group. For 10,000 patients treated for 1 year, there would be 284 (95% confidence interval [CI] 106 to 462) and 339 (95% CI 165 to 512) fewer events with rivaroxaban 20 mg or 10 mg than with aspirin.

INTERPRETATION

Compared with aspirin, extended anticoagulation with once daily rivaroxaban reduces recurrent VTE with a favourable benefit-risk profile.

FUNDING

Bayer AG.

Evaluation of a Soluble Fibrin Assay in Patients with Suspected Pulmonary Embolism

In order to determine the clinical utility of an enzyme immunoassay (EIA) for soluble fibrin in patients with suspected pulmonary embolism (PE), 195 unselected patients with suspected PE underwent blood sampling for measurement of plasma levels of soluble fibrin, and objective testing for PE. A soluble fibrin result of ≤ 0.75 Μg/ml showed a sensitivity of 100% for PE and a specificity of 12.8%, whereas a soluble fibrin result of ≤ 1.35 Μg/ml showed a sensitivity of 90.3% and a specificity of 49.4% for PE. The soluble fibrin assay has potential clinical utility in excluding PE.

Measurement of Markers of Activated Coagulation in Antithrombin III Deficient Subjects

Functional antithrombin III levels were measured by factor Xa inhibition in 63 members of a large family with type 2 antithrombin III deficiency and individuals were classified as antithrombin III deficient or non-deficient according to the results. FI+2 and TAT complexes were measured using an ELISA and FPA levels were measured by radioimmunoassay.

Thirty subjects (48%) were classified as antithrombin III deficient and 33 (52%) as antithrombin III non-deficient. The mean level of FI+2 was significantly higher in the deficient adults (0.87 ± 0.26) compared to both the non-deficient adults (0.70 ± 0.21) (p = 0.03) and the deficient adults receiving warfarin (0.16 ± 0.01) (p <0.001). The differences in the mean values of TAT complexes and FPA between deficient and non-deficient individuals were not statistically significant.

These findings suggest that untreated antithrombin III deficient subjects generate more thrombin than their non-deficient family members and that warfarin inhibits this thrombin formation. In this cross-sectional study, it is not possible to correlate the levels of the surrogate makers with future clinical outcome.

The Effect of Antithrombin III-Independent Thrombin Inhibitors and Heparin on Fibrin Accretion onto Fibrin-Coated Polyethylene

Prosthetic vascular grafts become coated with a layer of fibrin that contributes to graft thrombosis and occlusion. We compared the effect of antithrombin III-independent inhibitors of thrombin with heparin for their ability to prevent fibrin accretion onto a model of a vascular graft formed in vitro by coating polyethylene tubing with thrombin bound to a layer of polymerized fibrin. Equivalent antithrombin concentrations of heparin, D-Phe-Pro-Arg CH2Cl (PPACK), recombinant hirudin (r-hirudin), and Hirulog-1 were added to barium chloride-adsorbed plasma containing radiolabelled fibrinogen. Whereas, PPACK and r-hirudin persistently inhibited fibrin accretion, the inhibition by heparin was transient. Hirulog-1 had no effect on early fibrin accretion and was actually associated with enhanced accretion at 30 min (control 11.7 ± 2.0 μg fibrin/cm2; Hirulog-1, 18.4 ± 3.5 μg fibrin/cm2, p <0.001). Both Hirulog-1 and r-hirudin displaced radiolabelled thrombin from the fibrin surface. Whereas hirudin-thrombin complexes are stable, Hirulog-1 produces only transient inhibition of the displaced thrombin thereby accounting for the enhanced fibrin accretion with this anticoagulant. These studies show that the antithrombin III-independent inhibitors, r-hirudin and PPACK, are more effective inhibitors of fibrin accretion onto fibrin-coated polyethylene than heparin or Hirulog-1. In addition, they emphasize the importance of determining the ability of anticoagulants to displace thrombin from fibrin and to form stable thrombin-inhibitor complexes; lack of stability of thrombin-inhibitor complexes must be countered by levels of anticoagulant that are adequate to maintain its effectiveness.

Rivaroxaban for Stroke Prevention after Embolic Stroke of Undetermined Source

BACKGROUND

Embolic strokes of undetermined source represent 20% of ischemic strokes and are associated with a high rate of recurrence. Anticoagulant treatment with rivaroxaban, an oral factor Xa inhibitor, may result in a lower risk of recurrent stroke than aspirin.

METHODS

We compared the efficacy and safety of rivaroxaban (at a daily dose of 15 mg) with aspirin (at a daily dose of 100 mg) for the prevention of recurrent stroke in patients with recent ischemic stroke that was presumed to be from cerebral embolism but without arterial stenosis, lacune, or an identified cardioembolic source. The primary efficacy outcome was the first recurrence of ischemic or hemorrhagic stroke or systemic embolism in a time-to-event analysis; the primary safety outcome was the rate of major bleeding.

RESULTS

A total of 7213 participants were enrolled at 459 sites; 3609 patients were randomly assigned to receive rivaroxaban and 3604 to receive aspirin. Patients had been followed for a median of 11 months when the trial was terminated early because of a lack of benefit with regard to stroke risk and because of bleeding associated with rivaroxaban. The primary efficacy outcome occurred in 172 patients in the rivaroxaban group (annualized rate, 5.1%) and in 160 in the aspirin group (annualized rate, 4.8%) (hazard ratio, 1.07; 95% confidence interval [CI], 0.87 to 1.33; P=0.52). Recurrent ischemic stroke occurred in 158 patients in the rivaroxaban group (annualized rate, 4.7%) and in 156 in the aspirin group (annualized rate, 4.7%). Major bleeding occurred in 62 patients in the rivaroxaban group (annualized rate, 1.8%) and in 23 in the aspirin group (annualized rate, 0.7%) (hazard ratio, 2.72; 95% CI, 1.68 to 4.39; P<0.001).

CONCLUSIONS

Rivaroxaban was not superior to aspirin with regard to the prevention of recurrent stroke after an initial embolic stroke of undetermined source and was associated with a higher risk of bleeding. (Funded by Bayer and Janssen Research and Development; NAVIGATE ESUS ClinicalTrials.gov number, NCT02313909 .).

Mechanistic Basis for the Differential Effects of Rivaroxaban and Apixaban on Global Tests of Coagulation

Rivaroxaban and apixaban are both small molecules that reversibly inhibit factor Xa. Compared with rivaroxaban, apixaban has minimal effects on the prothrombin time and activated partial thromboplastin time. To investigate this phenomenon, we used a factor Xa-directed substrate in a buffer system. Although rivaroxaban and apixaban inhibited factor Xa with similar K _i values at equilibrium, kinetic measurements revealed that rivaroxaban inhibited factor Xa up to 4-fold faster than apixaban ( p  < 0.001). Using a discontinuous chromogenic assay to monitor thrombin production by prothrombinase in a purified system, rivaroxaban was 4-fold more potent than apixaban (K _i values of 0.7 ± 0.3 and 2.9 ± 0.5 nM, respectively; p  = 0.02). Likewise, in thrombin generation assays in plasma, rivaroxaban prolonged the lag time and suppressed endogenous thrombin potential to a greater extent than apixaban. To characterize how the two inhibitors differ in recognizing factor Xa, inhibition of prothrombinase was monitored in real-time using a fluorescent probe for thrombin. The data were fit using a mixed-inhibition model and the individual association and dissociation rate constants were determined. The association rates for the binding of rivaroxaban to either free factor Xa or factor Xa incorporated into the prothrombinase complex were 10- and 1,193-fold faster than those for apixaban, respectively, whereas dissociation rates were about 3-fold faster. Collectively, these findings suggest that rivaroxaban and apixaban differ in their capacity to inhibit factor Xa and provide a plausible explanation for the observation that rivaroxaban has a greater effect on global tests of coagulation than apixaban.

Non-vitamin K antagonist oral anticoagulants in atrial fibrillation patients with bioprosthetic valves

INTRODUCTION

The non-vitamin K antagonist oral anticoagulants (NOACs), which include dabigatran, apixaban, edoxaban and rivaroxaban, are preferred over vitamin K antagonists for stoke prevention in most patients with non-valvular atrial fibrillation. The NOACs are contraindicated in atrial fibrillation patients with rheumatic mitral stenosis or mechanical heart valves. There is evidence that bioprosthetic heart valves are less thrombogenic than mechanical heart valves, but it is unknown whether the risk of thromboembolism in atrial fibrillation patients with bioprosthetic valves differs from that in patients without such valves. Areas covered: The authors present a review of the efficacy and safety evidence surrounding the use of NOACs for stroke prevention in atrial fibrillation patients with bioprosthetic heart valves. Expert commentary: While the data is limited, there is no significant difference in thromboembolic, and bleeding outcomes in patients with AF and bioprosthetic heart valves treated with NOAC therapy. Future studies are required before definitive conclusions can be drawn regarding the safety and efficacy of NOAC therapy in AF patients bioprosthetic heart valves.

Peri-operative Adverse Outcomes in Patients with Atrial Fibrillation Taking Warfarin or Edoxaban: Analysis of the ENGAGE AF-TIMI 48 Trial

BACKGROUND

Peri-operative management of anticoagulated patients with atrial fibrillation (AF) is challenging. To gain information on the peri-operative management of edoxaban, we compared outcomes in patients on warfarin or edoxaban enrolled in ENGAGE AF-TIMI 48 who underwent a surgery or invasive procedure.

METHODS

Data from patients undergoing their first surgery/procedure were analysed and results compared by anticoagulant (warfarin vs. higher- or lower-dose edoxaban regimen [HDER and LDER, respectively]). Patients were classified by procedural management: anticoagulant interrupted (last dose 4-10 days pre-procedure) or anticoagulant continued (last dose ≤ 3 days pre-procedure). Stroke/systemic embolism (SSE), major bleeding (MB), MB or clinically relevant non-MB (CRNMB) and death were assessed from 7 days pre- until 30 days post-procedure. The chi-square test was used to compare outcomes across treatment groups.

RESULTS

A total of 7,193 patients (34%) underwent surgery/procedure: 3,116 had anticoagulant interrupted, 4,077 had anticoagulant continued. Among patients on warfarin, HDER and LDER who had anticoagulant interrupted, rates of SSE were 0.6, 0.5 and 0.9% (p = 0.53), rates of MB were 1.0, 1.2 and 1.1% (p = 0.94) and rates of MB or CRNMB were 3.9, 4.2 and 3.6% (p = 0.78); among patients on warfarin, HDER and LDER who had anticoagulant continued, rates of SSE were 1.1, 0.7 and 0.9% (p = 0.51), rates of MB were 3.6, 2.6 and 2.4% (p = 0.13) and rates of MB or CRNMB were 8.5, 7.9 and 6.6% (p = 0.17).

CONCLUSION

In patients requiring surgery/procedure in ENGAGE AF-TIMI 48, peri-operative rates of SSE, MB and death were not significantly different in patients who received edoxaban or warfarin.

Treatment Challenges in Venous Thromboembolism: An Appraisal of Rivaroxaban Studies

Venous thromboembolism (VTE) presents a continuing clinical burden to healthcare systems and there are patient groups for whom VTE management is challenging. Depending on the patient profile, the optimal duration of anticoagulation for VTE treatment can be unclear. EINSTEIN CHOICE was a Phase III, randomized, double-blind trial that compared the safety and efficacy of two once-daily (od) doses of the direct, oral factor Xa inhibitor rivaroxaban (20 and 10 mg) with acetylsalicylic acid (ASA; 100 mg daily) for prevention of recurrent VTE. Extended therapy with rivaroxaban at either dose was more effective than ASA at preventing recurrent VTE without increasing bleeding risk. Another group that is challenging to treat in the context of VTE is patients with cancer-associated thrombosis. Cancer is associated with a hypercoagulable state, while cancer treatment itself may increase VTE risk. Evidence supporting the use of non-vitamin K antagonist oral anticoagulants in patients with cancer is growing through specifically designed studies. Cancer Associated thrombosis-expLoring soLutions for patIentS through Treatment and prevention with rivarOxaban (CALLISTO) is an international research program exploring the role of rivaroxaban for the prevention and treatment of cancer-associated thrombosis. Here, we present overviews of three CALLISTO studies: PRO-LAPS II, CASTA-DIVA and COSIMO. Currently available and anticipated results from studies in a variety of patients at risk of or with VTE will provide valuable insights and seek to optimize future VTE management.

Edoxaban for the Treatment of Cancer-Associated Venous Thromboembolism

BACKGROUND

Low-molecular-weight heparin is the standard treatment for cancer-associated venous thromboembolism. The role of treatment with direct oral anticoagulant agents is unclear.

METHODS

In this open-label, noninferiority trial, we randomly assigned patients with cancer who had acute symptomatic or incidental venous thromboembolism to receive either low-molecular-weight heparin for at least 5 days followed by oral edoxaban at a dose of 60 mg once daily (edoxaban group) or subcutaneous dalteparin at a dose of 200 IU per kilogram of body weight once daily for 1 month followed by dalteparin at a dose of 150 IU per kilogram once daily (dalteparin group). Treatment was given for at least 6 months and up to 12 months. The primary outcome was a composite of recurrent venous thromboembolism or major bleeding during the 12 months after randomization, regardless of treatment duration.

RESULTS

Of the 1050 patients who underwent randomization, 1046 were included in the modified intention-to-treat analysis. A primary-outcome event occurred in 67 of the 522 patients (12.8%) in the edoxaban group as compared with 71 of the 524 patients (13.5%) in the dalteparin group (hazard ratio, 0.97; 95% confidence interval [CI], 0.70 to 1.36; P=0.006 for noninferiority; P=0.87 for superiority). Recurrent venous thromboembolism occurred in 41 patients (7.9%) in the edoxaban group and in 59 patients (11.3%) in the dalteparin group (difference in risk, -3.4 percentage points; 95% CI, -7.0 to 0.2). Major bleeding occurred in 36 patients (6.9%) in the edoxaban group and in 21 patients (4.0%) in the dalteparin group (difference in risk, 2.9 percentage points; 95% CI, 0.1 to 5.6).

CONCLUSIONS

Oral edoxaban was noninferior to subcutaneous dalteparin with respect to the composite outcome of recurrent venous thromboembolism or major bleeding. The rate of recurrent venous thromboembolism was lower but the rate of major bleeding was higher with edoxaban than with dalteparin. (Funded by Daiichi Sankyo; Hokusai VTE Cancer ClinicalTrials.gov number, NCT02073682 .).

Direct Oral Anticoagulants for Pulmonary Embolism: Importance of Anatomical Extent

Pulmonary embolism (PE) studies used direct oral anticoagulants (DOACs) with or without initial heparin. We aimed to (1) evaluate if PE patients benefit from initial heparin; (2) describe patient characteristics in the DOAC studies; and (3) investigate whether the anatomical extent of PE correlates with N-terminal pro-brain natriuretic peptide (NT-proBNP) levels, cause of PE, and recurrence rate. Our methods were (1) an indirect meta-analysis comparing the recurrence risk in DOAC-treated patients with or without initial heparin to those patients given heparin/vitamin K antagonist (VKA). (2) To compare the PE studies, information was extracted on baseline characteristics including anatomical extent. (3) The Hokusai-VTE study was used to correlate anatomical extent of PE with NT-proBNP levels, causes of PE, and recurrent venous thromboembolism (VTE). The meta-analysis included 11,539 PE patients. The relative risk of recurrent VTE with DOACs versus heparin/VKAs was 0.8 (95% confidence interval [CI]: 0.6–1.1) with heparin lead-in and 1.1 (95% CI: 0.8–1.5) without heparin. In the DOAC studies, the proportion of patients with extensive PE varied from 24 to 47%. In Hokusai-VTE, NT-proBNP was elevated in 4% of patients with limited and in over 60% of patients with extensive disease. Cause of PE and anatomical extent were not related. Recurrence rates increased from 1.6% with limited to 3.2% with extensive disease in heparin/edoxaban-treated patients, and from 2.4 to 3.9% in heparin/warfarin recipients. In conclusion, indirect evidence suggests a heparin lead-in before DOACs may be advantageous in PE. Anatomical extent was related to elevated NT-proBNP and outcome, but not to PE cause.

Global public awareness about atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is an important cause of ischemic stroke that often remains undetected until stroke occurs. Awareness of the risk factors and symptoms is important so that AF can be diagnosed and thromboprophylaxis given. However, the extent of public awareness of AF is uncertain. We assessed public awareness of AF across six continents and compared it with that of other thrombotic and non-thrombotic disorders.

METHODS

In collaboration with Ipsos-Reid, we conducted an internet-based, cross-sectional survey between September and October of 2016 in 10 countries: Argentina, Australia, Canada, Germany, Japan, Thailand, the Netherlands, Uganda, United Kingdom, and United States. Participants were selected from survey panels in weighted, age-stratified categories (40-60, 61-74, and ≥75 years). The survey included 11 questions about demographics and assessed awareness about AF, as well as that of other thrombotic and non-thrombotic disorders. Proportions and 95% confidence intervals (CI) were calculated.

RESULTS

Of a total of 6312 respondents, overall awareness of AF was 48% (95% CI, 46-50%), which was lower than awareness about other thrombotic and non-thrombotic disorders except for deep vein thrombosis (awareness 43%, 95% CI, 41-45%). Awareness about AF ranged from 25% to 69% across countries, while awareness of the risk factors for AF ranged from 8% to 52%, and awareness that AF leads to stroke ranged from 36% to 46%. Among those reporting awareness of AF, 82% correctly identified palpitations as an AF symptom.

CONCLUSIONS

Global public awareness of AF is low. Improving awareness may empower patients to seek timelier stroke preventive care.