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Background: Patients with immune thrombocytopenia are at risk of bleeding during surgery, and intravenous immunoglobulin is commonly used to increase the platelet count. We aimed to establish whether perioperative eltrombopag was non-inferior to intravenous immunoglobulin. Methods: We did a randomised, open-label trial in eight academic hospitals in Canada. Patients were aged at least 18 years, with primary or secondary immune thrombocytopenia and platelet counts less than 100 × 109 cells per L before major surgery or less than 50 × 109 cells per L before minor surgery. Previous intravenous immunoglobulin within 2 weeks or thrombopoietin receptor agonists within 4 weeks before randomisation were not permitted. Patients were randomly assigned to receive oral daily eltrombopag 50 mg from 21 days preoperatively to postoperative day 7 or intravenous immunoglobulin 1 g/kg or 2 g/kg 7 days before surgery. Eltrombopag dose adjustments were allowed weekly based on platelet counts. The randomisation sequence was generated by a computerised random number generator, concealed and stratified by centre and surgery type (major or minor). The central study statistician was masked to treatment allocation. The primary outcome was achievement of perioperative platelet count targets (90 × 109 cells per L before major surgery or 45 × 109 cells per L before minor surgery) without rescue treatment. We did intention-to-treat and per-protocol analyses using an absolute non-inferiority margin of –10%. This trial is registered with ClinicalTrials.gov, NCT01621204. Findings: Between June 5, 2013, and March 7, 2019, 92 patients with immune thrombocytopenia were screened, of whom 74 (80%) were randomly assigned: 38 to eltrombopag and 36 to intravenous immunoglobulin. Median follow-up was 50 days (IQR 49–55). By intention-to-treat analysis, perioperative platelet targets were achieved for 30 (79%) of 38 patients assigned to eltrombopag and 22 (61%) of 36 patients assigned to intravenous immunoglobulin (absolute risk difference 17·8%, one-sided lower limit of the 95% CI 0·4%; pnon-inferiority=0·005). In the per-protocol analysis, perioperative platelet targets were achieved for 29 (78%) of 37 patients in the eltrombopag group and 20 (63%) of 32 in the intravenous immunoglobulin group (absolute risk difference 15·9%, one-sided lower limit of the 95% CI –2·1%; pnon-inferiority=0·009). Two serious adverse events occurred in the eltrombopag group: one treatment-related pulmonary embolism and one vertigo. Five serious adverse events occurred in the intravenous immunoglobulin group (atrial fibrillation, pancreatitis, vulvar pain, chest tube malfunction and conversion to open splenectomy); all were related to complications of surgery. No treatment-related deaths occurred. Interpretation: Eltrombopag is an effective alternative to intravenous immunoglobulin for perioperative treatment of immune thrombocytopenia. However, treatment with eltrombopag might increase risk of thrombosis. The decision to choose one treatment over the other will depend on patient preference, resource limitations, cost, and individual risk profiles. Funding: GlaxoSmithKline and Novartis.

The International Initiative on Thrombosis and Cancer is an independent academic working group of experts aimed at establishing global consensus for the treatment and prophylaxis of cancer-associated thrombosis. The 2013, 2016, and 2019 International Initiative on Thrombosis and Cancer clinical practice guidelines have been made available through a free, web-based mobile phone application. The 2022 clinical practice guidelines, which are based on a literature review up to Jan 1, 2022, include guidance for patients with cancer and with COVID-19. Key recommendations (grade 1A or 1B) include: (1) low-molecular-weight heparins (LMWHs) for the initial (first 10 days) treatment and maintenance treatment of cancer-associated thrombosis; (2) direct oral anticoagulants for the initial treatment and maintenance treatment of cancer-associated thrombosis in patients who are not at high risk of gastrointestinal or genitourinary bleeding, in the absence of strong drug-drug interactions or of gastrointestinal absorption impairment; (3) LMWHs or direct oral anticoagulants for a minimum of 6 months to treat cancer-associated thrombosis; (4) extended prophylaxis (4 weeks) with LMWHs to prevent postoperative venous thromboembolism after major abdominopelvic surgery in patients not at high risk of bleeding; and (5) primary prophylaxis of venous thromboembolism with LMWHs or direct oral anticoagulants (rivaroxaban or apixaban) in ambulatory patients with locally advanced or metastatic pancreatic cancer who are treated with anticancer therapy and have a low risk of bleeding.

Eltrombopag has been shown to be noninferior to intravenous immunoglobulin (IVIG) for improving perioperative platelet counts in patients with immune thrombocytopenia (ITP) in a randomized trial; thus, cost is an important factor for treatment and policy decisions. We used patient-level data from the trial to conduct a cost-effectiveness analysis comparing perioperative eltrombopag 50 mg daily starting dose, with IVIG 1 or 2 g/kg (according to local practice) from a Canadian public health care payer’s perspective over the observation period, from preoperative day 21 to postoperative day 28. Resource utilization data were obtained from the trial data (eltrombopag, n = 38; IVIG, n = 36), and unit costs were collected from the Ontario Schedule of Benefits, Ontario Drug Formulary, and secondary sources. All costs were adjusted to 2020 Canadian dollars. We calculated the incremental cost per patient for all patients randomized. Uncertainty was addressed using nonparametric bootstrapping. The use of perioperative eltrombopag for patients with ITP resulted in a cost-saving of $413 Canadian per patient. Compared with IVIG, the probability of eltrombopag being cost effective was 70% even with no willingness to pay. In a sensitivity analysis based on IVIG dose, we found that with the higher dose of IVIG (2 g/kg), eltrombopag saved $2,714 per patient, whereas with the lower dose of IVIG (1 g/kg), eltrombopag had a higher mean cost of $562 per patient. In summary, based on data from the randomized trial that demonstrated noninferiority, the use of eltrombopag for the management of ITP in the perioperative setting was less costly than IVIG.

Objective To determine the efficacy and safety of dalteparin postoperative bridging treatment versus placebo for patients with atrial fibrillation or mechanical heart valves when warfarin is temporarily interrupted for a planned procedure. Design Prospective, double blind, randomised controlled trial. Setting 10 thrombosis research sites in Canada and India between February 2007 and March 2016. Participants 1471 patients aged 18 years or older with atrial fibrillation or mechanical heart valves who required temporary interruption of warfarin for a procedure. Intervention Random assignment to dalteparin (n=821; one patient withdrew consent immediately after randomisation) or placebo (n=650) after the procedure. Main outcome measures Major thromboembolism (stroke, transient ischaemic attack, proximal deep vein thrombosis, pulmonary embolism, myocardial infarction, peripheral embolism, or vascular death) and major bleeding according to the International Society on Thrombosis and Haemostasis criteria within 90 days of the procedure. Results The rate of major thromboembolism within 90 days was 1.2% (eight events in 650 patients) for placebo and 1.0% (eight events in 820 patients) for dalteparin (P=0.64, risk difference −0.3%, 95% confidence interval −1.3 to 0.8). The rate of major bleeding was 2.0% (13 events in 650 patients) for placebo and 1.3% (11 events in 820 patients) for dalteparin (P=0.32, risk difference −0.7, 95% confidence interval −2.0 to 0.7). The results were consistent for the atrial fibrillation and mechanical heart valves groups. Conclusions In patients with atrial fibrillation or mechanical heart valves who had warfarin interrupted for a procedure, no significant benefit was found for postoperative dalteparin bridging to prevent major thromboembolism. Trial registration Clinicaltrials.gov NCT00432796 .

Essentials Neutrophil extracellular traps (NETs) are generated during deep vein thrombosis (DVT). The role of interferon γ (IFNγ) and natural killer (NK) cells in NET formation was studied. IFNγ promote venous thrombosis through NET formation. NK cell depletion reduces DVT. SUMMARY: Background Neutrophils contribute to venous thrombosis through the release of neutrophil extracellular traps (NETs), but the mechanism triggering their formation remains unclear. In vitro data show that interferon (IFN)-γ induces the formation of NETs. Objectives To determine whether IFN-γ and the transcription factor T-box expressed on T cells (Tbet) promote venous thrombosis through neutrophil activation. Methods Venous thrombosis was induced by flow restriction in the inferior vena cava in IFN-γ-/- , Tbet-/- or wild-type (WT) mice. After 48 h, thrombus size was measured by the use of high-frequency ultrasound. NET formation was determined by immunofluorescence. Results and Conclusions Thrombus formation was reduced in Tbet-/- and IFN-γ-/- mice, suggesting that Tbet/IFN-γ-expressing cells are required for venous thrombosis. The number of NETs formed during thrombosis was significantly lower in Tbet-/- and IFN-γ-/- mice. NET formation was also decreased in WT mice treated with an IFN-γ-blocking antibody. Injection of recombinant IFN-γ into IFN-γ-/- mice rescued the phenotype. Natural killer (NK) cells were specifically depleted prior to venous thrombosis induction. NK cell depletion results in decreased NET formation and smaller thrombi, suggesting that NK cells are required for thrombus development. In depleted mice, adoptive transfer of WT NK cells induced a similar thrombosis burden as in WT mice. In contrast, adoptive transfer of IFN-γ -/- NK cells resulted in thrombi similar in size to those in depleted mice. In vitro, we showed that WT neutrophils released fewer NETs when they were cocultured with IFN-γ-/- NK cells. This study demonstrates that NK cell-dependent IFN-γ production is crucial for thrombus development by promoting the formation of NETs by neutrophils.

Introduction Coronavirus disease 2019 (COVID-19) is caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), a virus strain that appeared in Wuhan China in December 2019, that has since spread to become pandemic. An increased risk of venous and arterial thromboembolism has been consistently reported in critically ill patients with COVID-19 in several countries. The mechanism is thought to be multifactorial, largely mediated by the interplay between inflammation and the coagulation system, or thromboinflammation. We aim to report the risk of thrombosis in a Canadian patient population admitted to the intensive care unit (ICU) with COVID-19. Method We conducted a retrospective cohort study of all consecutive patients with COVID-19 admitted to the ICU between March 1st, 2020 and May 10th, 2020 at the Jewish General Hospital (JGH) in Montreal, Canada. The JGH is a tertiary care centre in Montreal, the epicenter of the COVID-19 pandemic in Canada, and the JGH was the first designated hospitalization centre in Montreal for COVID-19 patients. Patients were followed from date of ICU admission to the earliest of the following: objectively confirmed venous or arterial thrombosis; discharge from hospital; death; or study end date (May 24th, 2020). We determined risk of venous (pulmonary embolism (PE) and deep vein thrombosis (DVT)) and arterial (myocardial infarction, cerebrovascular accident, arterial limb ischemia, and mesenteric ischemia) thrombotic events. Results During the study period, a total of 90 patients admitted to the ICU with COVID-19 were included. The median age was 66 years (standard deviation (SD) 13.8), and 41.1% of patients were female. The median body mass index was 30 kg/m2(SD 5.1), and 64% of patients were mechanically ventilated and 10.1% received continuous renal replacement therapy. The median duration of follow-up was 17.1 days (SD 13.4). In all, 98.9% of patients were prescribed anticoagulation, among whom 78.2% were on a prophylaxis dose, 15.0% intermediate dose, and 6.9% therapeutic dose. In all, 11 (12.2%) patients developed a thrombotic complication among whom 9 patients had objectively diagnosed pulmonary embolism (PE) and 2 patients had an arterial thromboembolism. Both arterial events were cerebrovascular accidents. All PE episodes involved segmental arteries. One PE was incidental, and 3 patients had a concomitant diagnosis of DVT. Overall, death was observed in 16.7% of cohort patients and 12.2% of patients were still admitted to hospital at study end date. Conclusion In this first Canadian study of critically ill patients with COVID-19, we found a 12.2% risk of thrombotic complications despite almost 100% use of anticoagulation primarily with standard prophylaxis dosing. This risk is considerably lower than most reported estimates to date from critical care COVID-19 cohorts in Europe, China and the United States. Our results fuel the ongoing discussion of optimal dose of anticoagulation in these patients. Disclosures No relevant conflicts of interest to declare.

Background Direct oral anticoagulants (DOAC) are hydrophilic drugs with plasma levels inversely proportional to lean body mass. Sarcopenic patients with low muscle mass may be at risk for supra-therapeutic DOAC levels and bleeding complications. We therefore sought to examine the influence of lean body mass on DOAC levels in older adults with atrial fibrillation (AF). Methods A prospective cohort study was conducted with patients 65 years of age or more receiving rivaroxaban or apixaban for AF. Appendicular lean mass (ALM) was measured using a bioimpedance device and a dual X-ray absorptiometry scanner. DOAC levels were measured using a standardized anti-Xa assay 4 hours after (peak) and 1 hour before (trough) ingestion. Results The cohort consisted of 62 patients (47% female, 77.0 ± 6.1 years). The prescribed DOACs were apixaban 2.5 mg (21%), apixaban 5 mg (53%), and rivaroxaban 20 mg (26%). Overall, 16% had supra-therapeutic DOAC levels at trough and 25% at peak. In the multivariable logistic regression model, lower ALM was independently associated with supra-therapeutic DOAC levels at trough (odds ratio per ↓ 1-kg 1.23, 95% confidence interval 1.02 to 1.49) and peak (odds ratio per ↓ 1-kg 1.18, 95% confidence interval 1.02 to 1.37). Addition of ALM to a model consisting of age, total body weight, and renal function resulted in improved discrimination for supra-therapeutic DOAC levels. Conclusion Our proof-of-concept study has identified an association between ALM and DOAC levels in older adults with AF. Further research is needed to determine the impact of ALM on bleeding complications and the potential role of ALM-guided dosing for sarcopenic patients.

An amendment to this paper has been published and can be accessed via the original article.

Background There is uncertainty regarding the safety and effectiveness of direct oral anticoagulant agents in patients with antiphospholipid syndrome (APS). We performed a multicenter feasibility study to examine our ability to identify and obtain consent from eligible APS patients and to obtain 95% adherence with daily rivaroxaban administration, in order to inform and power a larger study. Clinical outcomes of bleeding and thrombosis were also collected. Methods APS patients with prior venous thromboembolism (VTE) were recruited over 2 years (Oct 2014–Sept 2016) and followed for ≥ 1 year. Patients were assessed clinically every 3 months and had pill counts performed every 6 months. Numbers of patients fulfilling study criteria, as well as those consenting to participate, were tracked, and percentage adherence based on pill counts was recorded. These data were compared against the feasibility endpoints. Rates of thrombosis and bleeding were calculated. Criterion for feasibility was obtaining consent from 135 of 150 identified APS patients over 2 years. Results Ninety-six eligible patients were identified, and 14 declined participation. Eighty-two patients were followed for a mean of 19 months, representing 129.8 patient-years. Average rivaroxaban adherence was 95.0%. During follow-up, there were 4 thromboembolic events (2 cerebrovascular and 2 VTE). There were no episodes of major bleeding. Conclusions Adequately powered comparative trials using patient-important outcomes in APS are unlikely to be successful due to inability to recruit sufficient numbers of study subjects. This study does not reveal a higher than expected risk of recurrent thromboembolic disease compared to historical cohorts; however, this is an uncontrolled study in relatively low-risk APS patients. Trial registration The study was registered with clinicaltrials.gov, identifier NCT02116036, April 16, 2014.

Background: Patients with immune thrombocytopenia (ITP) are at risk of bleeding during surgery. Intravenous immune globulin (IVIG) is a blood product that is commonly used to increase platelet counts before surgery or invasive procedures for patients with ITP; however, eltrombopag, an oral thrombopoietin receptor agonist, may be an effective alternative. Methods: We conducted a multicenter randomised trial to determine whether eltrombopag was non-inferior to IVIG for the achievement of perioperative platelet count targets without the use of rescue treatment. We did an intention to treat and per-protocol analysis using an absolute non-inferiority margin of -10%. Secondary endpoints were thrombosis, bleeding, adverse events and treatment satisfaction. We enrolled 74 patients with ITP who had a planned major or minor surgery and with a platelet count below 100 x109/L or 50 x109/L respectively. Patients were randomised to receive oral daily eltrombopag from 21 days preoperatively, or IVIG (1 or 2g per kg) seven days preoperatively. Findings: By intention to treat, perioperative platelet targets were achieved by 30 of 38 patients (78·9%) assigned to eltrombopag and 22 of 36 patients (61·1%) assigned to IVIG (absolute difference, 17·8%; one-sided lower limit of the 95% confidence interval, 0·4%; p=0·005 for non-inferiority). Results were similar for patients who completed the protocol. One patient in the eltrombopag group developed a pulmonary embolism 14 days after minor surgery, and one patient in the IVIG group developed a distal deep vein thrombosis 30 days after major surgery. There was no difference in bleeding or adverse events. Patients reported higher treatment satisfaction with eltrombopag. Interpretation: Eltrombopag was no worse than IVIG for the achievement of platelet count targets around the time of surgery for patients with ITP. This population may be at increased risk of thrombosis. Trial Registration: www.clinicaltrials.gov number as NCT01621204. Funding Statement: This trial was funded by GlaxoSmithKline and Novartis. Declaration of Interests: N.M.H., R.J.C., M.B., J.K., A.T., M.S., M.W., P.V., J.C., N.L., S.L., and J.G.K. report no competing financial interests. D.M.A. reports grants from GlaxoSmithKline and Novartis during the conduct of the study; grants and/or personal fees from Novartis, Amgen, Bristol Myers Squibb, UCB, Principia, and Rigel outside the submitted work. C.H. reports personal fees from Novartis, Amgen, and GSK, outside the submitted work. E.J. reports personal fees from Novartis, outside the submitted work. M.S. reports personal fees from Novartis, outside the submitted work. Y.L. reports grants from Novartis during the conduct of the study, and other fees from Pfizer, outside the submitted work. L.L. reports personal fees from Novartis during the conduct of the study. S.A. reports grants from Novartis NL during the conduct of the study; grants from Amgen, outside the submitted work. W.L. reports personal fees from Novartis, outside the submitted work. Ethics Approval Statement: The trial was approved by the research ethics boards at each participating center. The study was conducted in accordance with the Declaration of Helsinki and Good Clinical Practice guidelines.

Objective We directly compared the Villalta scale and the Venous Clinical Severity Score (VCSS) to determine which of the two measures would be better at capturing clinically important cases of post-thrombotic syndrome (PTS) and PTS severity compared with patient-reported quality of life (QOL) scores. Methods We performed a secondary analysis of the ATTRACT (acute venous thrombosis: thrombus removal with adjunctive catheter-directed thrombolysis) trial study population. We calculated the correlations of the Villalta scores and VCSSs with QOL scores (short-form 36-item health survey [SF-36] physical component summary [PCS] and mental component summary [MCS]; and VEINES [venous insufficiency epidemiological and economic study]-QOL/symptom [VEINES-QOL/Sym] questionnaire) at each study visit (6, 12, 18, and 24 months of follow-up). The correlation of the random intercept (mean scores) and random slope (rate of change of the scores) among the Villalta scores, VCSS, and VEINES-QOL/Sym scores was assessed using a multivariate longitudinal model. Results The median correlation between Villalta scores and VCSSs was 0.72. The median correlation between the Villalta scores and VEINES-QOL and VEINES-Sym scores at all follow-up visits was −0.68 and −0.71, respectively. The median correlation between the Villalta scores and SF-36 PCS and MCS scores was −0.51 and −0.31, respectively. For the VCSSs, the median correlation with the VEINES-QOL and VEINES-Sym scores at all follow-up visits was −0.39 and −0.41, respectively. The median correlation between the VCSSs and SF-36 PCS and MCS scores was −0.32 and −0.13, respectively. The correlations between the random effects in the multivariate longitudinal models showed a similar pattern. The effect of covariate adjustment by age, sex, and body mass index was minor. Conclusions The Villalta scores and VCSSs correlated strongly. The Villalta scale showed a substantially greater correlation with venous disease-specific and general QOL scores compared with the correlation with the VCSS. Our findings suggest that when a single scale is used to assess for clinically meaningful PTS, the Villalta scale will better capture the effects of PTS on patient-reported QOL.

Introduction Venous thromboembolism (VTE), which includes deep vein thrombosis and pulmonary embolism remains the third most common cause of mortality among all cardiovascular diseases. Studies support intertwined roles of innate inflammatory systems and thrombosis in the pathogenesis of VTE. Toll-like receptors (TLRs) are transmembrane proteins that play pivotal roles in the innate immune system by detecting « pathologic ligands » and transducing signals into a prothrombotic state. Endogenous RNA, released from cells under pathological conditions, has been identified as a potent pro-coagulant factor and a ligand for TLR3. We hypothesize that eRNA and TLR3 promote venous thrombosis development after vessel injury. Methods The ferric chloride (FeCl3) model was used to induce venous thrombosis in mice. WT or TLR3 deficient (-/-) mice received an i.v. injection of either vehicle, a specific fluorescent probe for RNA (Syto RNA Select), RNase1, poly (I:C) or RNA extracted from murine endothelial cells (eRNA). Human umbilical vein endothelial cells (HUVECs) were treated with siRNA directed against TLR3 or an IL-8 receptor (CXCR2) antagonist. Results Using a cell-permeant nucleic acid stain, we demonstrated that FeCl3 promoted RNA release in vivo and thus increased the RNA content in the thrombus. Therefore, RNase 1 treatment reduced thrombus size compared to mice injected with vehicle. In contrast, eRNA and poly (I:C) increased thrombus size in WT mice whereas no modifications were observed in TLR3-/- mice. Poly (I:C) and eRNA treatments bolstered neutrophil infiltration in WT but not in TLR3-/- mice. Similarly, the expression of citrullinated histone 3 (CitH3), a neutrophil extracellular traps (NETs) biomarker, was heightened by poly (I:C) and eRNA in WT but not in TLR3/- mice. In vitro, eRNA stimulated CXCL5 mRNA expression, a murine isoform of human IL-8, in WT but not in TLR3-/- endothelial cells. ELISA analysis corroborated that CXCL5 expression is induced by eRNA via TLR3 in endothelial cells. To confirm these data, human endothelial cells treated with poly (I:C) were transfected with siRNA targeting TLR3. This contributes to the abolition of neutrophil recruitment as compared with control siRNA. The administration of an IL-8 receptor (CXCR2) antagonist to the human endothelial cells abrogated neutrophil infiltration. Conclusions These results suggest that eRNA through TLR3 enhances neutrophil recruitment and NET formation leading to venous thrombosis.

Objective—Coagulation and inflammation are inter-related. Gas6 (growth arrest–specific 6) promotes venous thrombosis and participates to inflammation through endothelial-innate immune cell interactions. Innate immune cells can provide the initiating stimulus for venous thrombus development. We hypothesize that Gas6 promotes monocyte recruitment during venous thrombosis.Approach and Results—Deep venous thrombosis was induced in wild-type and Gas6-deficient (−/−) mice using 5% FeCl3and flow reduction in the inferior vena cava. Total monocyte depletion was achieved by injection of clodronate before deep venous thrombosis. Inflammatory monocytes were depleted using an anti–C-C chemokine receptor type 2 (CCR2) antibody. Similarly, injection of an anti–chemokine ligand 2 (CCL2) antibody induced CCL2 depletion. Flow cytometry and immunofluorescence were used to characterize the monocytes recruited to the thrombus. In vivo, absence of Gas6 was associated with a reduction of monocyte recruitment in both deep venous thrombosis models. Global monocyte depletion by clodronate leads to smaller thrombi in wild-type mice. Compared with wild type, the thrombi from Gas6−/−mice contain less inflammatory (CCR2hiCX3CR1lo) monocytes, consistent with a Gas6-dependent recruitment of this monocyte subset. Correspondingly, selective depletion of CCR2hiCX3CR1lomonocytes reduced the formation of venous thrombi in wild-type mice demonstrating a predominant role of the inflammatory monocytes in thrombosis. In vitro, the expression of both CCR2 and CCL2 were Gas6 dependent in monocytes and endothelial cells, respectively, impacting monocyte migration. Moreover, Gas6-dependent CCL2 expression and monocyte migration were mediated via JNK (c-Jun N-terminal kinase).Conclusions—This study demonstrates that Gas6 specifically promotes the recruitment of inflammatory CCR2hiCX3CR1lomonocytes through the regulation of both CCR2 and CCL2 during deep venous thrombosis.

International audience; Venous thromboembolism (VTE) is the second leading cause of death in patients with cancer. These patients are at a high risk of VTE recurrence and bleeding during anticoagulant therapy. The International Initiative on Thrombosis and Cancer is an independent academic working group aimed at establishing a global consensus for the treatment and prophylaxis of VTE in patients with cancer. The International Initiative on Thrombosis and Cancer last updated its evidence-based clinical practice guidelines in 2016 with a free, web-based mobile phone application, which was subsequently endorsed by the International Society on Thrombosis and Haemostasis. The 2019 International Initiative on Thrombosis and Cancer clinical practice guidelines, which are based on a systematic review of the literature published up to December, 2018, are presented along with a Grading of Recommendations Assessment Development and Evaluation scale methods, with the support of the French National Cancer Institute. These guidelines were reviewed by an expanded international advisory committee and endorsed by the International Society on Thrombosis and Haemostasis. Results from head-to-head clinical trials that compared direct oral anticoagulant with low-molecular-weight heparin are also summarised, along with new evidence for the treatment and prophylaxis of VTE in patients with cancer.

Background The Bridging ITP Trial is an open-label randomized trial designed to compare the oral thrombopoietin receptor agonist eltrombopag and intravenous immune globulin (IVIG) for patients with immune thrombocytopaenia (ITP) who require an increase in platelet count before elective surgery. Here, we report the study methods and rationale. Methods We designed a multi-centre, non-inferiority randomized trial comparing daily oral eltrombopag starting 3 weeks pre-operatively, and IVIG administered 1 week pre-operatively for patients with ITP requiring a platelet count increase prior to surgery. Starting dose of eltrombopag is 50 mg daily with a weekly pre-operative dose titration schedule, and treatment is continued for 1 week after surgical haemostasis is achieved. IVIG is administered at a dose of 1 to 2 g/kg 1 week pre-operatively with the allowance for a second dose within 1 week after surgical haemostasis. The objective of the study is to demonstrate non-inferiority of eltrombopag for the primary endpoint of achieving the pre-operative platelet count threshold (50 × 109/L for minor surgery; or 100 × 109/L for major surgery) and sustaining platelet count levels above the threshold for 1 week after surgical haemostasis is achieved, without the use of rescue treatment. Secondary endpoints include thrombosis, bleeding and patient satisfaction. Conclusion The Bridging ITP Trial will evaluate the efficacy and safety of eltrombopag as an alternative to IVIG in the peri-operative setting for patients with ITP. The protocol was designed to provide a management strategy that can be applied in clinical practice. ClinicalTrials.gov Identifier NCT01621204.

Importance: Patients with atrial fibrillation (AF) who use a direct oral anticoagulant (DOAC) and request elective surgery or procedure present a common clinical situation yet perioperative management is uncertain. Objective: To investigate the safety of a standardized perioperative DOAC management strategy. Design, Setting, and Participants: The Perioperative Anticoagulation Use for Surgery Evaluation (PAUSE) cohort study conducted at 23 clinical centers in Canada, the United States, and Europe enrolled and screened patients from August 1, 2014, through July 31, 2018. Participants (n = 3007) had AF; were 18 years of age or older; were long-term users of apixaban, dabigatran etexilate, or rivaroxaban; were scheduled for an elective surgery or procedure; and could adhere to the DOAC therapy interruption protocol. Interventions: A simple standardized perioperative DOAC therapy interruption and resumption strategy based on DOAC pharmacokinetic properties, procedure-associated bleeding risk, and creatinine clearance levels. The DOAC regimens were omitted for 1 day before a low-bleeding-risk procedure and 2 days before a high-bleeding-risk procedure. The DOAC regimens were resumed 1 day after a low-bleeding-risk procedure and 2 to 3 days after a high-bleeding-risk procedure. Follow-up of patients occurred for 30 days after the operation. Main Outcomes and Measures: Major bleeding and arterial thromboembolism (ischemic stroke, systemic embolism, and transient ischemic attack) and the proportion of patients with an undetectable or minimal residual anticoagulant level (

Introduction Venous thromboembolism (VTE) remains the third most common cause of mortality among all cardiovascular diseases. Innate inflammatory mechanisms contribute to the pathogenesis of VTE. Toll-like receptors (TLRs) play pivotal roles in the innate immune system by detecting “danger signals”. Endogenous RNA has been identified as a potent procoagulant factor in thrombosis and may possibly act through TLR3. Objective To investigate how eRNA mediate procoagulant effects through endothelial TLR3 in venous thrombosis. Methods The FeCl3 model was used to induce venous thrombosis in WT or TLR3 deficient (-/-) mice. A specific fluorescent probe for RNA (Syto RNA Select), RNase1, poly(I:C) or RNA extracted from murine endothelial cells (eRNA) were injected to mice. HUVECs were treated with poly(I:C) or eRNA extracted from HEK 293 cells in the presence of a TLR3 antagonist. Gene expression and signaling pathways activated were analyzed using western blot and real-time quantitative PCR. Turbidimetric measurement of plasma clot formation was performed by incubating HUVECs treated with poly(I:C) or eRNA with human plasma. Results We found that FeCl3 promoted RNA release in vivo and increased the RNA content within the thrombus. RNase1 treatment reduced thrombus size compared to control mice. In contrast, eRNA and poly(I:C) treatment increased thrombus size in WT mice whereas no modifications were observed in TLR3-/- mice. Hence, poly(I:C) and eRNA treatments bolstered neutrophil infiltration in WT but not in TLR3-/- mice. In vitro, eRNA stimulated the release of CXCL5 in WT but not in TLR3-/- endothelial cells. In addition, eRNA enhanced plasma clot formation by downregulating thrombomodulin mRNA expression. These effects are mediated through NFkB activation. Conclusion These results suggest that eRNA through TLR3 enhances neutrophil recruitment and clot formation leading to venous thrombosis.

Unusual site deep vein thrombosis (USDVT) is an uncommon form of venous thromboembolism (VTE) with heterogeneity in pathophysiology and clinical features. While the need for anticoagulation treatment is generally accepted, there is little data on optimal USDVT treatment. The TRUST study aimed to characterize the epidemiology, treatment and outcomes of USDVT. From 2008 to 2012, 152 patients were prospectively enrolled at 4 Canadian centers. After baseline, patients were followed at 6, 12 and 24months. There were 97 (64%) cases of splanchnic, 33 (22%) cerebral, 14 (9%) jugular, 6 (4%) ovarian and 2 (1%) renal vein thrombosis. Mean age was 52.9years and 113 (74%) cases were symptomatic. Of 72 (47%) patients tested as part of clinical care, 22 (31%) were diagnosed with new thrombophilia. Of 138 patients evaluated in follow-up, 66 (48%) completed at least 6months of anticoagulation. Estrogen exposure or inflammatory conditions preceding USDVT were commonly associated with treatment discontinuation before 6months, while previous VTE was associated with continuing anticoagulation beyond 6months. During follow-up, there were 22 (16%) deaths (20 from cancer), 4 (3%) cases of recurrent VTE and no fatal bleeding events. Despite half of USDVT patients receiving6months of anticoagulation, the rate of VTE recurrence was low and anticoagulant treatment appears safe. Thrombophilia testing was common and thrombophilia prevalence was high. Further research is needed to determine the optimal investigation and management of USDVT.

Background: Whether the level of patient’s knowledge about warfarin plays any role in maintenance of therapeutic international normalized ratio (INR) is controversial. Several studies have looked at patients’ warfarin knowledge and the level of patients’ anticoagulation control (AC). Most studies had small numbers and did not use validated questionnaires. Objectives: To use the Oral Anticoagulation Knowledge (OAK) test to assess patients’ knowledge of AC and to examine associations between knowledge, INR, and adverse events. Methods: In this cross-sectional study, patients were asked to complete the OAK test. Data on clinical and demographic characteristics, INR values, and thrombosis or bleeding events during the preceding 1 year period were collected. Associations between OAK scores, patient characteristics, proportion of therapeutic INRs, and bleeding/thrombosis events were assessed. Results: A total of 225 patients completed the OAK test. Mean (SD) age was 70 (13.4) years, 53% were male, and 75% were on warfarin for >3 years. Over the preceding year, 57.3% of INRs were therapeutic, and there were 22 bleeding and 6 thrombotic events. The mean OAK score was 12/20 (passing score = 15/20); 64% of patients failed the OAK test. Predictors of passing the OAK test were younger age ( P = .01) and higher level of education ( P = .03). There was no association between OAK score and proportion of therapeutic INRs, or OAK score and bleeding or thrombosis events. Conclusion: We used the OAK test to assess patients’ AC knowledge. Results suggests that while younger and more educated patients were more likely to pass the OAK test, the OAK test results may not predict INR control or occurrence of bleeding or thrombotic events.

Background: Growth arrest-specific 6 (Gas6)-deficient mice are protected against venous thromboembolism (VTE), suggesting a role for Gas6 in this disorder. We previously demonstrated that Gas6 induces forkhead box O1 (FoxO-1) phosphorylation through the phosphoinositide 3-kinase-Akt pathway. FoxO-1 regulates the expression of vascular cell adhesion molecule-1 (VCAM-1), a molecule that has been implicated in VTE. Objectives: To assess the role of FoxO-1 in Gas6-dependent VCAM-1 expression. Methods: Thrombin was used to stimulate endothelial cells (ECs). Wild-type (WT) and Gas6 ECs were transfected with small interfering RNA targeting Axl or FoxO-1, a luciferase-coupled plasmid containing the FoxO-1 consensus sequence, and a phosphorylation-resistant FoxO-1 mutant, or treated with an Akt inhibitor. VCAM-1 mRNA expression was measured by real time-qPCR. VCAM-1 protein expression and FoxO-1 and Akt phosphorylation were assessed by western blot analysis. FoxO-1 localization was assessed by immunofluorescence. Adhesion of bone marrow mononuclear cells (BM-MCs) on ECs was assessed by fluorescence. Results and conclusions: Thrombin induces both VCAM-1 expression and FoxO-1 phosphorylation and nuclear exclusion in WT ECs only. Silencing of FoxO-1 enhances VCAM-1 expression in both WT and Gas6 ECs. Inhibition of Akt or FoxO-1 phosphorylation prevents VCAM-1 expression in WT ECs. These data show that Gas6 induces FoxO-1 phosphorylation, leading to derepression of VCAM-1 expression. BM-MC-EC adhesion is increased by thrombin in WT ECs. BM-MC-EC adhesion is further increased when FoxO-1 is silenced, but decreased when FoxO-1 phosphorylation is inhibited. These results demonstrate that the Gas6-FoxO-1 signaling axis plays an important role in VCAM-1 expression in the context of VTE by promoting BM-MC-EC adhesion.

Venous thrombosis is a common condition affecting 1 - 2% of the population, with an annual incidence of 1 in 500. Venous thrombosis can lead to death through pulmonary embolism or results in the post-thrombotic syndrome, characterized by chronic leg pain, swelling, and ulceration, or in chronic pulmonary hypertension resulting in significant chronic respiratory compromise. This is the most common cardiovascular disease after myocardial infarction and ischemic stroke and is a clinical challenge for all medical disciplines, as it can complicate the course of other disorders such as cancer, systemic disease, surgery, and major trauma. Experimental models are necessary to study these mechanisms. The stasis model induces consistent thrombus size and a quantifiable amount of thrombus. However, it is necessary to systematically ligate side branches of the inferior vena cava to avoid variability in thrombus sizes and any erroneous data interpretation. We have developed a non-invasive technique to measure thrombus size using ultrasonography. Using this technique, we can assess thrombus development and resolution over time in the same animal. This approach limits the number of mice required for quantification of venous thrombosis consistent with the principle of replacement, reduction, and refinement of animals in research. We have demonstrated that thrombus weight and histological analysis of thrombus size correlate with measurement obtained with ultrasonography. Therefore, the current study describes how to induce deep vein thrombosis in mice using the inferior vena cava stasis model and how to monitor it using high frequency ultrasound.

Background Post-thrombotic syndrome (PTS) occurs in 20-50% of patients following proximal deep vein thrombosis (DVT), despite anticoagulation treatment. The International Society on Thrombosis and Haemostasis recommends using the Villalta scale to standardize the diagnosis of PTS and to quantify its severity. However, many investigators use the Venous Clinical Severity Score (VCSS) to assess PTS. Different to the Villalta score, the VCSS was developed as a measure for chronic venous disease and not PTS specifically. The aim of the study was to determine which of Villalta and VCSS best captures clinically important PTS and PTS severity by analyzing the relationship of each to QoL scores in the Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis (ATTRACT) trial study population. Methods A secondary analysis of the ATTRACT randomized controlled clinical trial was conducted. 621 ATTRACT patients with symptomatic proximal DVT are included in this analysis. Correlations of the Villalta and VCSS scores with QoL scores (Short-Form Health Survey-36 physical component score/mental component score [SF-36 PCS/MCS]; the Venous Insufficiency Epidemiological and Economic Study-QoL/Symptoms [VEINES-QoL/Sym] questionnaire) were examined at study visits. The correlation of the random intercept (mean scores) and random slope (rate of change of the scores) between the Villalta, VCSS and the VEINES-QoL/Sym scores was assessed using a multivariate longitudinal model. Results The mean age at enrolment was 51 years of age, 78% were white, 62% were male, the mean BMI was 32 kg/m2, 57% had iliofemoral DVT, 19% had a previous ipsilateral DVT and 93% were taking one or more anticoagulation therapies prior to randomization. The median (range) correlation coefficients across all follow-up visits for the Villalta scale and VEINES-QOL and the Villalta scale and VEINES-Sym were -0.73 (0.51, -0.73) and -0.75 (-0.50, -0.76), respectively. The median (range) correlation coefficients for the Villalta scale and the SF-36 PCS or the SF-36 MCS across all follow-up visits were -0.51 (-0.35, -0.54) and -0.31 (-0.21, -0.38), respectively. In all correlation analyses between the Villalta scale and QoL measures, correlations at baseline were the weakest, and then increased until 6 months, after which the correlation coefficients remained relatively constant. The median correlation coefficient (range) across all follow-up visits for VCSS and VEINES-QOL and for VCSS and VEINES-Sym were -0.39 (-0.37, -0.39) and -0.41 (-0.36, -0.41), respectively. The median correlation (range) between VCSS and SF-36 PCS and for VCSS and MCS were -0.32 (-0.31, -0.32) and -0.12 (-0.12, -0.14), respectively. The magnitude of the correlations remained relatively constant from 6 months to 24 months follow-up visits. The Villalta scale had a strong negative correlation with VEINES-QoL and VEINES-Sym, a moderate negative correlation with SF-36 PCS, and a weak negative correlation with SF-36 MCS. Conversely, the VCSS had a weak negative correlation with VEINES-QoL, VEINES-Sym and SF-36 PCS, and a very weak negative correlation with SF-36 MCS. Adjustment for age, sex, ethnicity, race, extent of DVT and previous ipsilateral DVT did not change our findings. Each pair of disease severity scales and QoL scales were analyzed as a multivariate outcome in a multivariate longitudinal model. A random intercept (mean scores) and random slope (rate of change of the scores) were present in all these multivariate longitudinal models. The impact of covariates (i.e. age, sex and BMI) was also examined. The Villalta score and VCSS score have a positive correlation between their random intercept and random slope. This suggests that patients with a higher average Villalta score also tend to have a higher average VCSS score (correlation is 0.74 and 0.69 if adjusted). Those that have a higher rate of change in Villalta score over time tend to have a higher rate of change in VCSS (correlation is 0.72 and 0.84 if adjusted). The impact from covariate adjustment by age, sex and BMI was minor. Conclusion For all measures, the Villalta scale has a substantially higher correlation with QOL than the VCSS. Our findings support the use of the Villalta scale to assess PTS in preference to VCSS, as it better captures the impact of PTS on patient reported QoL, a key consideration in patients with chronic PTS.

Background The perioperative management of patients who take a direct oral anticoagulant (DOAC) for atrial fibrillation and require treatment interruption for an elective surgery/procedure is a common clinical scenario for which best practices are uncertain. The Perioperative Anticoagulant Use for Surgery Evaluation (PAUSE) study is designed to address this unmet clinical need. We discuss the rationale for the PAUSE design and analysis plan as well as the rationale supporting the perioperative DOAC protocol. Methods PAUSE is a prospective study with three parallel cohorts, one for each DOAC, to assess a standardized but patient-specific perioperative management protocol for DOAC-treated patients with atrial fibrillation. The perioperative protocol accounts for DOAC type, patient's renal function and surgery/procedure-related bleeding risk. The primary study aim is to demonstrate the safety of the PAUSE protocol for the perioperative management of each DOAC. The secondary aim is to determine the effect of the pre-procedure interruption on residual anticoagulation when measured by the dilute thrombin time for dabigatran and anti-factor Xa levels for rivaroxaban and apixaban. The study hypothesis is that the perioperative management protocol for each DOAC is safe for patient care, defined by expected risks for major bleeding of 1% (80% power to exclude 2%), and for arterial thromboembolism of 0.5% (80% power to exclude 1.5%) in each DOAC group. Conclusion The PAUSE study has the potential to establish a standard-of-care approach for the perioperative management of DOAC-treated patients. The PAUSE management protocol is designed to be easily applied in clinical practice, as it is standardized and also patient specific.

In this study, we develop an analytical framework for personalizing the anticoagulation therapy of patients who are taking warfarin. Consistent with medical practice, our treatment design consists of two stages: (i) the initiation stage, modeled using a partially-observable Markov decision process, during which the physician learns through systematic belief updates about the unobservable patient sensitivity to warfarin, and (ii) the maintenance stage, modeled using a Markov decision process, during which the physician relies on his formed belief about patient sensitivity to determine the stable, patient-specific, warfarin dose to prescribe. We develop an expression for belief updates in the POMDP, establish the optimality of the myopic policy for the MDP, and derive conditions for the existence and uniqueness of a myopically optimal dose. We validate our models using a real-life patient data set gathered at the Hematology Clinic of the Jewish General Hospital in Montreal. The proposed analytical framework and case study enable us to develop useful clinical insights, for example, concerning the length of the initiation period and the importance of correctly assessing patient sensitivity.

Over- and undercoagulation with warfarin are associated with hemorrhagic and thromboembolic events, respectively. Genetic and clinical factors affect warfarin response, and the causes of this variability remain unclear. We present descriptive statistics and test for predictors of poor anticoagulation control. The Quebec Warfarin Cohort (QWC) comprises 1059 new warfarin users, with prospective follow-up using telephone questionnaires every 3 months for 1 year, and using healthcare administrative databases (RAMQ and Med-Echo) for 5 years prior to cohort entry and up to 10 years following active patient participation. Genetic material was collected, and genotyping of CYP2C9 and VKORC1 genes was conducted. Measured outcomes included the percentage of time patients spent within therapeutic range, anticoagulation control, warfarin dose, bleeding, and thromboembolic events. We report baseline characteristics and outcomes after 1 year of follow-up. Poor anticoagulation control was defined as time in therapeutic range

In the Original Article by Douketis et al. "The Perioperative Anticoagulant Use for Surgery Evaluation (PAUSE) Study for Patients on a Direct Oral Anticoagulant who Need an Elective Surgery or Procedure: Design and Rationale (Thromb Haemost 2017;117:2415-2424; DOI: 10.1160/TH17-08-0553), the authors have identified two errors that they wish to correct: First, on page 2419, second paragraph, Clinical Outcomes subheading, the authors state that, "The primary clinical outcomes are arterial thromboembolism, comprising stroke (ischemic or haemorrhagic), systemic embolism or transient ischemic attack and major bleeding. The inclusion of "haemorrhagic stroke is incorrect as only ischemic strokes are included in their definition of an arterial thromboembolism outcome. The definitions of study outcomes are correctly indicated in Appendix A (pg. 2424) of the paper, where the authors state: "The second primary outcome is arterial thromboembolism, comprising (1) ischemic stroke, defined as any new focal neurologic deficit that persists for 24 hours or any new focal neurologic deficit of any duration that occurs with evidence of acute infarction on computed tomography (CT) or magnetic resonance imaging (MRI) of the brain; (2) systemic embolism, defined as symptomatic embolism to upper or lower extremity or abdominal organ, confirmed intraoperatively or by objective imaging studies (e.g. CT angiography) and (3) transient ischemic attack, defined as symptomatic focal neurologic deficit (lasting typically 1 hour) that occurs with no evidence of acute infarction on CT/MRI of the brain. Second, the depiction of the pre-procedure interruption interval for dabigatran-treated patientswith a CrCl 50 mL/min is incorrect in Figure 1 (pg. 2418) of the paper, as the arrow should extend so it reflects 2 days off treatment (i.e., day -2 and day -1). The incorrect (currently published) version is shown below, with incorrect area shaded in red: (Figure Presented).

Background: Patients with immune thrombocytopenia (ITP) may require treatment to raise the platelet count before surgery. Intravenous immune globulin (IVIG) is commonly used for this purpose, but eltrombopag, an oral thrombopoietin receptor agonist, may be a good alternative. We compared perioperative eltrombopag or IVIG for the achievement of platelet count targets for major or minor surgery. Methods: We conducted a randomized, non-inferiority trial at 8 centers in Canada.ITP patients with a platelet count Results: From 2013 to 2019, 38 patients were assigned to received eltrombopag and 36 patients were assigned to receive IVIG before major (n= 31) or minor (n= 43) surgery. Five patients did not complete the study. By intention to treat, 30/38 (78.9%) patients on eltrombopag achieved perioperative platelet count targets compared with 22/36 (61.1%) on IVIG (absolute risk difference, 17.8%; one-sided lower limit of the 95% confidence interval, 0.4%; p=0.005 for non-inferiority). Results were similar in the per protocol analysis (absolute risk difference: 15.8%; one-sided lower limit of the 95% CI, -2.1%; p=0.009). Eltrombopag was superior to IVIG in the intention-to-treat analysis (p=0.047) but not in the per-protocol analysis (p =0.074). One patient developed pulmonary embolism 14 days after minor surgery (skin biopsy) and 7 days after stopping eltrombopag when the platelet count was 135 x109/L. Of 18 patients who underwent splenectomy on study, marked post-splenectomy thrombocytosis (platelets >1,000 x109/L) occurred in 2 (11.1%) patients, both of whom were on eltrombopag. Global treatment satisfaction scores were higher for eltrombopag. Conclusion: Eltrombopag is non-inferior and may be superior to IVIG for achieving target platelet counts perioperatively for patients with ITP. Post-operative thromboprophylaxis should be considered with eltrombopag. Funding Source:This was an investigator-initiated trial funded by Novartis. Disclosures Arnold: Novartis: Honoraria, Research Funding; Rigel: Consultancy, Research Funding; Bristol-Myers Squibb: Research Funding; Principia: Consultancy. Heddle:Novartis: Research Funding. Hsia:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria; Jansen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Sholzberg:Novartis: Honoraria; Amgen: Honoraria, Research Funding. Lin:Pfizer: Consultancy; Novartis: Research Funding; Octapharma: Research Funding; Amgen: Consultancy. Larratt:Novartis: Honoraria. Amini:Amgen NL: Research Funding; Novartis NL: Research Funding. Schipperus:Novartis: Research Funding. Lim:Pfizer Canada: Consultancy, Honoraria; Portola Pharmaceuticals: Consultancy; Bristol-Myers Squibb: Honoraria. OffLabel Disclosure: Eltrombopag is not licenced for perioperative treatment in patients with ITP.

OBJECTIVES: Warfarin (W) is a highly prescribed anticoagulant for the treatment and prevention of thromboembolic diseases. However, anticoagulation stability is often a challenge due to the narrow therapeutic range of the drug. In recent years, dietary vitamin K (VK) has emerged as an important modulator of long-term anticoagulation stability. In trials, patients receiving small doses of supplemental VK (100–150 mg/d) spend significantly more time in the therapeutic range (%TTR) and present fewer bleeding and thrombotic complications. Whether similar beneficial effects can be achieved through diet remains unknown. We determined whether increasing dietary VK intake by ≥150 µg/day improves anticoagulation stability of W-treated patients with a history of INR instability. METHODS: We conducted a 24-week randomized controlled trial at the Anticoagulation Clinics of the Montreal Heart Institute and the Jewish General Hospital (Montreal). The main inclusion criteria were: 1) be anticoagulated for >6 months with a target international normalized ratio (INR) range of 2.0–3.0 or 2.5–3.5, and 2) present a %TTR

Recent evidence suggests that warfarin use may be associated with a reduced risk of prostate cancer. We aimed to determine whether exposure to warfarin is also associated with a reduced risk of prostate cancer death. A nested case–control study was conducted within a population-based cohort of 10,012 men aged ≥50 years with newly diagnosed prostate cancer between 1985 and 2002 and with no history of cancer since 1970 using the linked records of Saskatchewan Health and Saskatchewan Cancer Agency registry. We identified 2,309 cases who died of prostate cancer during follow-up. For each case, one control alive at the time of the case’s death and matched for length of follow-up (±6 months) was randomly selected. Prescription counts were used to define warfarin exposure. Multivariate conditional logistic regression analysis was used to calculate the adjusted incidence rates of prostate cancer death in relation to warfarin use while adjusting for confounding by age, year of prostate cancer diagnosis, clinical stage and grade of cancer at diagnosis, Chronic Disease Score, and use of warfarin before diagnosis. Ever use of warfarin following a diagnosis of prostate cancer was associated with an adjusted rate ratio of 1.44 (95 % confidence interval (CI) 1.33–1.84) for prostate cancer death. The adjusted rate ratio with one-year use of warfarin was 1.77 (95 % CI 1.25–2.50) compared to never use. The unadjusted rate ratio with five-year use of warfarin was 0.64 (95 % CI 0.40–1.00) and remained unchanged in the adjusted analysis (0.65, 95 % CI 0.37–1.13), although no longer statistically significant. Our study does not provide conclusive evidence for a protective effect of long-term warfarin on prostate cancer-specific mortality. Moreover, short-term warfarin use may be associated with an increased risk of prostate cancer death.

Gas6 (growth-arrest specific gene 6) plays a role in thrombus stabilization. Gas6 null (−/−) mice are protected from lethal venous and arterial thromboembolism through platelet signaling defects induced only by 5μM ADP and 10μM of the thromboxane analog, U46619. This subtle platelet defect, despite a dramatic clinical phenotype, raises the possibility that Gas6 from a source other than platelets contributes to thrombus formation. Thus, we hypothesize that Gas6 derived from the vascular wall plays a role in venous thrombus formation. Bone marrow transplantation and platelet depletion/reconstitution experiments generating mice with selective ablations of Gas6 from either the hematopoietic or nonhematopoietic compartments demonstrate an approximately equal contribution by Gas6 from both compartments to thrombus formation. Tissue factor expression was significantly reduced in the vascular wall of Gas6−/− mice compared with WT. In vitro, thrombin-induced tissue factor expression was reduced in Gas6−/− endothelial cells compared with wild-type endothelium. Taken together, these results demonstrate that vascular Gas6 contributes to thrombus formation in vivo and can be explained by the ability of Gas6 to promote tissue factor expression and activity. These findings support the notion that vascular wall-derived Gas6 may play a pathophysiologic role in venous thromboembolism.

Background— The most important complication of atrial fibrillation (AF) is thromboembolic stroke. Although AF-related remodeling is considered important in atrial thrombogenesis, its role never has been directly tested. This study assessed effects of AF-related remodeling on the atrial thrombogenic milieu by using radiofrequency ablation (RFA) to create a quantifiable prothrombotic nidus. Methods and Results— We studied normal control dogs (control, n=16) and 3 canine AF-models: (1) atrial tachycardia remodeling (ATR; n=16) induced by atrial tachypacing (400 bpm for 1 week, with atrioventricular block and ventricular pacing at 80 bpm); (2) congestive heart failure (CHF; n=14) attribu table to ventricular tachypacing (240 bpm for 2 weeks); and (3) chronic AF (CAF; n=8) induced by atrial tachypacing (35±3 days) without atrioventricular block. CAF dogs had AF for 13±1 days until euthanization. After remodeling was established, RFA lesions were created in both atria. Half the ATR and CHF dogs were subjected to atrial tachypacing during 7-day post-RFA follow-up. Electrophysiological and echocardiographic studies were performed before RFA and 7 days after RFA, and then hearts were removed and atrial thrombi were quantified by histomorphometry. Burst-pacing–induced AF duration was significantly greater in ATR, CHF, and CAF groups versus control group. The atrial effective refractory period shortened in ATR and CAF groups. Left atrial diameter was significantly larger with CHF, but not with ATR. Neither total thrombus volume nor thrombus volume per lesion differed significantly among groups. Table. Properties of Ablation Lesions and Atrial Thrombi Experimental Group Control (n=16) ATR (n=16) CHF (n=14) CAF (n=8) N of ablation lesions per dog 6.9±0.3 6.6±0.2 7.2±0.2 6.9±0.4 Ablation lesion area, mm 2 53.1±3.5 58.3±4.8 57.7±4.9 44.3±3.7 Ablation lesion depth, mm 5.2±0.2 5.1±0.3 5.3±0.2 5.2±0.2 Ablation lesion volume, mm 3 205.2±17.8 211.6±17.6 231.5±29.0 176.8±22.2 N of thrombi per dog 5.4±0.4 4.7±0.3 5.6±0.4 6.5±0.4 Presence of thrombus, % 80±5 72±5 77±6 95±3 Mean thrombus volume in both atria, mm 3 20.8±3.4 14.9±2.2 12.2±2.6 22.5±5.6 Mean thrombus volume in left atria, mm 3 8.2±1.5 4.0±0.9 5.5±1.6 8.1±3.3 Mean thrombus volume in right atria, mm 3 30.1±5.4 22.7±4.3 17.9±4.1 32.8±8.3 Total thrombus volume in both atria, mm 3 140.5±21.3 99.7±16.8 86.1±17.5 131.1±22.7 Total thrombus volume in left atria, mm 3 22.8±5.3 11.8±3.3 17.0±3.7 23.3±6.4 Total thrombus volume in right atria, mm 3 117.7±21.5 87.8±17.2 69.1±16.1 107.8±23.3 Thrombus volume normalized to ablation lesion area in both atria, mm 3 /mm 2 0.5±0.1 0.4±0.1 1.5±1.1 0.8±0.3 Thrombus volume normalized to ablation lesion volume in both atria 0.2±0.1 0.1±0.0 0.5±0.4 0.3±0.1 ATR indicates atrial tachycardia remodeling; CAF, chronic atrial fibrillation; and CHF, congestive heart failure. There were no statistically significant differences for any groups vs control group for any of these variables studied. Conclusions— None of the AF substrates tested, including sustained atrial tachycardia/AF itself, enhanced post-RFA atrial thrombus formation. Indices of electrical and structural remodeling did not predict post-RFA thrombogenic potential. Contrary to widely held but previously untested notions, we were unable to demonstrate prothrombotic effects of AF-related remodeling.

Background A rapid method of reversal is required for patients on warfarin who suffer acute bleeding or require emergency surgery. Prothrombin complex concentrates (PCCs) have recently been recommended by the Canadian Blood Services for use at a fixed low dose of 1000 IU of Factor (F)IX activity. The main goal of this study was to investigate both the effectiveness and the safety of fixed low-dose PCCs. Study Design and Methods We retrospectively reviewed charts from 103 patients who received PCCs for reversal of warfarin therapy. Results A total of 103 patients were treated with PCC at a single fixed dose of 1000 IU of F IX activity. Fifty patients (48.5%) had a final international normalized ratio (INR) response of not more than 1.5 and an additional 45 patients (43.7%) had a final INR response between 1.6 and 2.0. However, 86 patients (83.5%) had an excellent clinical response consisting of control of bleeding without the requirement of additional measures. In a multivariable model, patients who received fresh-frozen plasma and patients who were given doses greater than 1000 IU of PCC were both identified as predictors of a poor clinical response (odds ratio [OR] 3.48, 95% confidence interval [CI] 0.76-15.89, p = 0.11; and OR 10.8, 95% CI 2.08-56.28, 95% CI, p = 0.005, respectively). There were five adverse events up to 30 days after PCC use. Conclusion At a fixed dose of 1000 IU of F IX activity, PCC seems to be effective and safe but randomized controlled trials, specifically examining different doses of PCC, are required to confirm the above observations.

Summary. Background: Venous thrombosis (VT) is an important cause of morbidity and mortality in clinical medicine. Animal models studying venous thrombosis are scarce and, in most cases, very crude and rely on sacrificing the animals to excise formed thrombi. Developing an in vivo murine model of venous thrombosis can be a powerful tool for studying venous thrombosis. Objectives: We sought to use a high-frequency ultrasound system (HFUS) to dynamically and non-invasively monitor thrombus formation in the inferior vena cava (IVC) of mice. Methods: We developed a murine model of venous thrombosis using, for detection, the Vevo 770®, a micro-imaging HFUS. Two different thrombosis models were used to generate thrombi in the IVC of C57Bl/6NCr mice: (i) ligation and (ii) application of ferric chloride (FeCl3). We then assessed venous thrombosis by HFUS. Results: In both models, measurements of the clot pathologically correlated favorably with measurements acquired with HFUS. Thrombus develops less than an hour after ligation or FeCl3-induced injury of the IVC and the size of the clot increases over time for up to 24 h. Importantly, we demonstrate that HFUS can be used to monitor the effect of an anticoagulant such as dalteparin until complete resolution of the thrombus. Conclusions: These data show that HFUS assesses venous thrombosis in mice reliably and non-invasively. Developing a murine model of thrombosis using more accurate, and clinically more relevant, techniques such as ultrasonography, is a step towards a better understanding of the pathophysiology of venous thromboembolism.

In this study, we validated a thromboelastography (TEG) method to evaluate the hemostatic effects of 3 peptides. The first peptide is an ideal amphipathic peptide composed of 22 leucine and lysine in a ratio of 2:1. At a very low concentration, the peptide had a procoagulant effect shown by decreases in reaction time (R) and coagulation time (K) but was impaired by a decrease in maximum amplitude (MA). At higher concentrations, the peptide had an anticoagulant effect. The α angle was minimally affected by the peptide. The second peptide is melittin derived from bee venom. Melittin showed procoagulant effects reflected by a decrease in clotting time but led to lower MA. The third peptide derived from fibrinogen γ chain promoted hemostasis only at an optimal concentration and became anticoagulant at a higher concentration. The hemostatic mechanisms of each peptide were discussed. Our study would facilitate further development of peptides for either hemorrhage control or thrombosis treatment.

Hyperhomocysteinemia (HHcy) has been shown to induce endothelial dysfunction in part as a result of enhanced oxidative stress. Function and survival of endothelial progenitor cells (EPCs, defined as sca1+c-kit+flk-1+bone marrow-derived cells), which significantly contribute to neovascularization and endothelial regeneration, depend on controlled production of reactive oxygen species (ROS). Mice heterozygous for the gene deletion of methylenetetrahydrofolate reductase ( Mthfr+/−) have a 1.5- to 2-fold elevation in plasma homocysteine. This mild HHcy significantly reduced the number of circulating EPCs as well as their differentiation. Mthfr deficiency was also associated with increased ROS production and reduced nitric oxide (NO) generation in Mthfr+/−EPCs. Treatment of EPCs with sepiapterin, a precursor of tetrahydrobiopterin (BH4), a cofactor of endothelial nitric oxide synthase (eNOS), significantly reduced ROS and improved NO production. mRNA and protein expression of eNOS and the relative amount of eNOS dimer compared with monomer were decreased by Mthfr deficiency. Impaired differentiation of EPCs induced by Mthfr deficiency correlated with increased senescence, decreased telomere length, and reduced expression of SIRT1. Addition of sepiapterin maintained cell senescence and SIRT1 expression at levels comparable to the wild type. Taken together, these results demonstrate that Mthfr deficiency impairs EPC formation and increases EPC senescence by eNOS uncoupling and downregulation of SIRT1.

Background It remains uncertain if patients with atrial fibrillation or mechanical heart valves requiring interruption of warfarin for procedures benefit from post-procedure anticoagulant bridging therapy. Methods In order to determine the efficacy and safety of postoperative LMWH bridging, we conducted a multicenter randomized double-blind controlled trial of patients with atrial fibrillation or a mechanical heart valve who require interruption of warfarin for a planned procedure. We excluded patients with active bleeding within 30 days, platelet count Results Starting in October 2006 we randomized a total of 1471 patients of whom 1167 had atrial fibrillation (without mechanical heart valves) and 304 had mechanical valves (99 also had atrial fibrillation). Last follow up was completed in May 2016. Baseline characteristics were similar between the LMWH and the placebo groups (see Table 1). Due to a randomization program system error at two centres more atrial fibrillation patients were randomized to dalteparin rather than to placebo. Major thromboembolism occurred in 6/820 (0.71%) dalteparin patients and 7/650 (1.11%) placebo patients. Major post-procedure bleeding occurred in 12 (1.46%) dalteparin patients and 16 (2.46%) placebo patients. Findings were similar in patients with atrial fibrillation alone and in patients with mechanical heart valves (with or without atrial fibrillation) (Table 2). Conclusions In patients with atrial fibrillation and/or mechanical heart valves who had warfarin interrupted for a procedure there was no benefit from post-procedure LMWH bridging. Disclosures Kovacs: Bayer: Research Funding; Daiichi Sankyo Pharma Development: Research Funding. Wells:Janssen: Honoraria; Sanofi: Honoraria; BMS: Honoraria, Research Funding; Bayer: Honoraria. Schulman:Boehringer-Ingelheim: Honoraria, Research Funding; Daiichi-Sankyo: Honoraria; Sanofi: Honoraria; Bayer: Honoraria.

Introduction: The perioperative management of patients who are taking a direct oral anticoagulant (DOAC) for atrial fibrillation (AF) and require an elective surgery/procedure is uncertain. No studies have addressed the timing of perioperative DOAC interruption and resumption, and if perioperative heparin bridging and coagulation function testing are needed. The Perioperative Anticoagulant Use for Surgery Evaluation (PAUSE) Study hypothesized that a simple, standardized perioperative management strategy, based on DOAC-specific interruption and resumption intervals, that foregoes perioperative heparin bridging and coagulation function testing, is safe for patient care, with associated low rates of major bleeding (1%) and arterial thromboembolism (0.5%). We postulated that this management yields a high proportion of patients (>90%) with a minimal to no DOAC level at surgery/procedure. Methods: PAUSE is a prospective study with 3 parallel DOAC cohorts of patients with AF taking apixaban, dabigatran or rivaroxaban and requiring anticoagulant interruption for an elective surgery/procedure. Patients were managed using a standardized protocol based on DOAC pharmacokinetic properties, procedure-associated bleeding risk (Appendix 1) and creatinine clearance (CrCl). DOACs were interrupted for 1 day before and after surgery for a low bleed risk surgery and 2 days before and after a high bleed surgery; longer interruption was done in patients on dabigatran with a CrCl Results: We enrolled 3007 patients from 23 sites in Canada, the U.S. and Europe (Appendix 4). The patient characteristics were (Figure 2): mean age 72.5 years; 66.1% male; 33.5% high bleeding risk surgery/procedure, with 1257 patients in the apixaban cohort, 668 in the dabigatran cohort and 1082 in the rivaroxaban cohort (Table 1). DOAC interruption and resumption intervals are shown in Table 2. The 30-day postoperative rate (95% CI) of major bleeding was 1.35% (0-2.00) in the apixaban cohort, 0.90% (0-1.73) in the dabigatran cohort and 1.85% (0-2.65) in the rivaroxaban cohort; the rate (95% CI) of arterial thromboembolism was 0.16% (0-0.48) in the apixaban cohort, 0.6% (0-1.33) in the dabigatran cohort and 0.37% (0-0.82) in the rivaroxaban cohort (Table 3). There were 2541 (84.5%) patients with preoperative DOAC levels measured: a level Conclusions: In patients with AF who were taking a DOAC (apixaban, dabigatran, rivaroxaban) and required anticoagulant interruption for an elective surgery/procedure, using a standardized DOAC-specific perioperative management strategy was safe for patient care, with associated low rates of perioperative MB (90% overall; 98.8% at high bleeding risk) had a minimal or no residual DOAC level at the time of the surgery/procedure. PAUSE is the largest study, to date, that addresses how to manage the common problem of perioperative DOAC management. It is likely to have a practice-changing impact and will inform future practice guidelines in perioperative care. Study Funding: CIHR (313156) and the H&S Foundation of Canada (G-14-0006136). Aniara-Hyphen Biomed (assays). Acknowledgments: We thank Drs. Walter Ageno, David Garcia, Lehana Thabane, Wendt Lim, Lori Linkins, William Ristevski, and Demetrios J. Sahlas. Also, Kayla Lucier, Grace Wang, Tara McDougall, and HRLMP and CRLB. Supported by CanVector and REDCap. Disclosures Douketis: Bayer: Other: Advisory Board; Janssen: Consultancy; BMS: Other: Advisory Board; Biotie: Other: Advisory Board; Daiichi-Sankyo: Other: Advisory Board; Boehringer-Ingelheim: Consultancy, Other: Advisory Board, Research Funding; The Medicines Company: Other: Advisory Board; Sanofi: Consultancy, Other: Advisory Board; Astra-Zeneca: Other: Advisory Board; Portola: Other: Advisory Board; Pfizer: Other: Advisory Board. Spyropoulos:Janssen Scientific Affairs, LLC: Consultancy. Carrier:Bayer: Honoraria; Leo Pharma: Research Funding; Pfizer: Honoraria; BMS: Honoraria, Research Funding. Vanassche:Bayer: Consultancy; Boehringer Ingelheim: Consultancy; BMS/Pfizer: Consultancy. Verhamme:Bayer: Honoraria, Research Funding; Medtronic: Honoraria; Portola: Honoraria; Boehringer Ingelheim: Honoraria; Leo Pharma: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Daiichi-Sankyo: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding. Shivakumar:Pfizer: Honoraria; Servier: Honoraria; Bayer: Honoraria; LEO Pharma: Honoraria. Gross:Pfizer: Honoraria; Bayer: Honoraria; LEO Pharma: Honoraria; Servier: Honoraria. Lee:Pfizer: Consultancy, Research Funding; BMS: Research Funding; Servier: Honoraria; LEO Pharma: Consultancy, Research Funding; Bayer: Consultancy, Honoraria. Le Templier:BMS-pfizer: Honoraria. Wu:Leo Pharma: Honoraria; Pfizer: Honoraria; BMS-Pfizer: Honoraria. Coppens:Bayer: Honoraria, Other: Non-financial support, Research Funding; CSL Behring: Honoraria, Other: non-financial support, Research Funding; Uniqure BV: Research Funding. Arnold:Bristol Myers Squibb: Research Funding; UCB: Consultancy; Amgen: Consultancy, Research Funding; UCB: Consultancy; Amgen: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Bristol Myers Squibb: Research Funding; Novartis: Consultancy, Research Funding. Caprini:Alexion Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Recovery Force: Consultancy; BMS: Membership on an entity's Board of Directors or advisory committees; Pfizor: Membership on an entity's Board of Directors or advisory committees; Janssen R&D: Membership on an entity's Board of Directors or advisory committees. Summer:Octapharma: Honoraria. Schulman:Daiichi-Sankyo: Honoraria; Bayer: Honoraria; Sanofi: Honoraria; Boehringer-Ingelheim: Honoraria, Research Funding.

BACKGROUND: Pulmonary embolism is a common condition. Some patients subsequently develop chronic thromboembolic pulmonary hypertension (CTEPH). Many care gaps exist in the diagnosis and management of CTEPH patients including lack of awareness, incomplete diagnostic assessment, and inconsistent use of surgical and medical therapies.METHODS: A representative interdisciplinary panel of medical experts undertook a formal clinical practice guideline development process. A total of 20 key clinical issues were defined according to the patient population, intervention, comparator, outcome (PICO) approach. The panel performed an evidence-based, systematic, literature review, assessed and graded the relevant evidence, and made 26 recommendations.RESULTS: Asymptomatic patients postpulmonary embolism should not be screened for CTEPH. In patients with pulmonary hypertension, the possibility of CTEPH should be routinely evaluated with initial ventilation/ perfusion lung scanning, not computed tomography angiography. Pulmonary endarterectomy surgery is the treatment of choice in patients with surgically accessible CTEPH, and may also be effective in CTEPH patients with disease in more ‘distal’ pulmonary arteries. The anatomical extent of CTEPH for surgical pulmonary endarterectomy is best assessed by contrast pulmonary angiography, although positive computed tomography angiography may be acceptable. Novel medications indicated for the treatment of pulmonary hypertension may be effective for selected CTEPH patients.CONCLUSIONS: The present guideline requires formal dissemination to relevant target user groups, the development of tools for implementation into routine clinical practice and formal evaluation of the impact of the guideline on the quality of care of CTEPH patients. Moreover, the guideline will be updated periodically to reflect new evidence or clinical approaches.

SummaryUnanticipated elevation of the INR is common in patients receiving warfarin. We performed a prospective cohort study of 107 warfarintreated patients with INR values of more than 10 who received a single 2.5 mg dose of oral vitamin K. During the first week, one patient experienced major bleeding, and one died. In the first 90 days after enrolment four patients had major bleeding (3.7%, 1.0% to 9.3%), eight patients (7.5%, 3.3% to 14.2%) died and two had objectively confirmed thromboembolism. Based on our low rate of observed major bleeding we conclude that 2.5 mg of oral vitamin K is a reasonable treatment for patients with INR values of more than 10 who are not actively bleeding.

Summary. Background: Growth Arrest Specific gene product 6 (gas6) is a γ-carboxylated protein that protects endothelial cells against apoptosis. Gas6 has previously been shown to induce phospatidyl-3-inositol-kinase (PI3K)/Akt signaling. Other studies have demonstrated a link between PI3K/Akt signaling and forkhead transcription factors in endothelial cells. Objective: To test the hypothesis that gas6 promotes cell survival via a forkhead-dependent pathway. Results and Conclusions: Treatment of serum-starved human umbilical vein endothelial cells (HUVECs) with gas6 induced time-dependent phosphorylation and nuclear exclusion of FOXO1a. This effect was suppressed by the PI3K inhibitor wortmannin, demonstrating that FOXO1a phosphorylation is PI3-kinase dependent. Transduction of HUVECs with a phosphorylation-resistant form of FOXO1a [triple mutant (TM)-FOXO1a] abrogated the pro-survival effect of gas6 on serum-starved endothelial cells. Finally, treatment of serum-starved HUVECs with gas6 resulted in a reduction of FOXO1a transcriptional activity and downregulation of the pro-apoptotic gene, p27kip1. Taken together, these findings suggest that gas6 protects endothelial cells from apoptosis by a mechanism that involves PI3K-Akt-dependent inactivation of FOXO1a.

Haemophilia B is characterized by a deficiency of the gamma-carboxylated protein, factor IX (FIX). As a first step to optimize a gene therapy strategy to treat haemophilia B, we employed a previously described approach (Biochemistry 2000;39: 14322) of altering the propeptide of vitamin K-dependent proteins in vitro, to improve the carboxylation efficiency of FIX. Both native FIX and FIX with a prothrombin propeptide (proPT-FIX) produced recombinant FIX in vitro following transfection of their cDNAs into human embryonic kidney (HEK) 293 cells. Using hydroxyapatite chromatography to separate carboxylated from uncarboxylated FIX, we are able to show that >90% of FIX is gamma-carboxylated and that substituting the propeptide of prothrombin into FIX does not further increase the relative amounts of carboxylated material. These results demonstrate that the nature of the propeptide, per se is not the sole determinant of optimal carboxylation of FIX in our expression system in HEK 293 cells.