End-of-trial inflammatory biomarkers, lipid levels, creatine kinase and markers of renal and liver function in the LoDoCo2 trial

Background

The Low-Dose Colchicine 2 (LoDoCo2) trial demonstrated that colchicine reduced major cardiovascular events in patients with chronic coronary artery disease (CAD). The effect of long-term colchicine treatment on inflammatory biomarkers and markers reflecting renal and liver function have not been investigated yet.

Purpose

This substudy examines levels of inflammatory biomarkers, lipid fractions, creatine kinase (CK) and markers of renal and liver function at close-out of the trial.

Methods

The LoDoCo2 trial randomly assigned patients with chronic CAD to colchicine 0.5 mg once daily or placebo. Blood samples were drawn during close-out visits after a median follow-up of 32.7 (interquartile range [IQR] 24.0–48.6) months.

Results

Assignment to colchicine was associated with lower levels of high-sensitivity C-Reactive Protein (0.94 mg/L [0.53–1.93] vs. 1.24 mg/L [0.73–2.55]; −24.2%; p<0.01) and interleukin-6 (2.70 ng/L [1.79–4.18] vs. 3.16 ng/L [2.07–4.95]; −14.9%; p<0.01), but was not associated with any differences in lipid fractions or markers of renal function. Although CK levels were higher after colchicine (123.0 U/L, [84.0–184.0] vs. 110.0 U/L, [77.0–164.0], p<0.01), the number of participants with marked elevations of CK (>5 times upper limit of normal [ULN]) was low and not different between treatment groups. Levels of alanine aminotransferase (ULN 40 U/L) and albumin (ULN 50 U/L) were higher (p<0.01) in the colchicine group compared to placebo (30.0 U/L [22.0–40.0] vs. 26.0 U/L [19.0–34.0] and 43.01 g/L±2.39 vs. 42.64 g/L±2.48, respectively). There were no differences in gamma-glutamyl transferase or bilirubin.

Conclusion

Long-term low-dose colchicine in patients with chronic CAD was associated with lower levels of hs-CRP and IL-6 but was not associated with clinically important differences in lipid fractions, CK, renal or liver function.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): The National Health Medical Research Council of AustraliaThe Netherlands Organization for Health Research and Development

The effects of colchicine in patients with diabetes mellitus and chronic coronary artery disease: a post-hoc analysis of the LoDoCo2-trial

Background

Atherosclerosis is an inflammatory disease and is accelerated by diabetes mellitus (DM). Patients with chronic coronary artery disease (CAD) who also have DM are at high risk of recurrent cardiovascular events. The role of inflammation in atherosclerosis is well established, whereas the role of inflammation on incident and progression of DM has been hypothesized. The nucleotide-binding oligomerization domain-, leucine-rich repeat-, and pyrin domain-containing protein 3 (NLRP3) inflammasome in particular, may play an important role in the onset and progression of T2DM. The anti-inflammatory drug colchicine attenuates the NLRP3-inflammasome. The Low-Dose Colchicine 2 (LoDoCo2) trial showed that colchicine reduces cardiovascular risk in patients with chronic CAD.

Purpose

The purpose of this study was to assess the effects of colchicine in patients with chronic CAD and DM on cardiovascular events as well as the effect of colchicine on the development of new-onset DM.

Methods

The LoDoCo2 trial randomized 5522 to placebo or colchicine, with a median follow-up of 28.6 months (interquartile range 20.5–44.4). The primary endpoint was a composite of cardiovascular death, spontaneous myocardial infarction, ischaemic stroke, or ischaemia-driven revascularization. Secondary outcomes consisted of the aforementioned events, separately. Cox proportional hazards models were used to investigate univariable associations between DM status for all endpoints in the placebo group. The interactions between treatment group and DM status were evaluated with the addition of treatment and the treatment-by-DM variable interaction.

Results

In total, 1007 participants (18.2%) had DM at baseline. The hazard ratio for the primary endpoint was 0.87 (95% CI, 0.61–1.25) in those with DM and 0.64 (95% CI, 0.51–0.80) in those without DM (p for interaction>0.05). Treatment effects of colchicine were consistent over all secondary endpoints (p for interaction>0.05). The incidence of new-onset DM was 1.5% (34/2270) in the colchicine group and 2.2% (49/2245) in the placebo group (p=0.10). Participants with DM were at higher risk for all endpoints. The primary composite end point in the placebo group occurred in 13.0% (67/515) patients with DM and in 8.8% (197/2245) of the patients without DM (unadjusted hazard ratio 1.54 [95% CI 1.16–2.03, p<0.01]) compared to the group without DM. DM was also strongly associated with the occurrence of all secondary end points.

Conclusion

This study shows that the beneficial effects of colchicine on cardiovascular endpoints are consistent regardless of DM status. The data indicate that larger trials are needed to assess whether colchicine reduces the incidence of new-onset DM.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): National Health Medical Research Council of Australia and the Netherlands Organization for Health Research and Development

Randomised comparative effectiveness trial of Pulmonary Embolism Prevention after hiP and kneE Replacement (PEPPER): the PEPPER trial protocol

INTRODUCTION

More than 1 million elective total hip and knee replacements are performed annually in the USA with 2% risk of clinical pulmonary embolism (PE), 0.1%-0.5% fatal PE, and over 1000 deaths. Antithrombotic prophylaxis is standard of care but evidence is limited and conflicting. We will compare effectiveness of three commonly used chemoprophylaxis agents to prevent all-cause mortality (ACM) and clinical venous thromboembolism (VTE) while avoiding bleeding complications.

METHODS AND ANALYSIS

Pulmonary Embolism Prevention after HiP and KneE Replacement is a large randomised pragmatic comparative effectiveness trial with non-inferiority design and target enrolment of 20 000 patients comparing aspirin (81 mg two times a day), low-intensity warfarin (INR (International Normalized Ratio) target 1.7-2.2) and rivaroxaban (10 mg/day). The primary effectiveness outcome is aggregate of VTE and ACM, primary safety outcome is clinical bleeding complications, and patient-reported outcomes are determined at 1, 3 and 6 months. Primary data analysis is per protocol, as preferred for non-inferiority trials, with secondary analyses adherent to intention-to-treat principles. All non-fatal outcomes are captured from patient and clinical reports with independent blinded adjudication. Study design and oversight are by a multidisciplinary stakeholder team including a 10-patient advisory board.

ETHICS AND DISSEMINATION

The Institutional Review Board of the Medical University of South Carolina provides central regulatory oversight. Patients aged 21 or older undergoing primary or revision hip or knee replacement are block randomised by site and procedure; those on chronic anticoagulation are excluded. Recruitment commenced at 30 North American centres in December 2016. Enrolment currently exceeds 13 500 patients, representing 33% of those eligible at participating sites, and is projected to conclude in July 2024; COVID-19 may force an extension. Results will inform antithrombotic choice by patients and other stakeholders for various risk cohorts, and will be disseminated through academic publications, meeting presentations and communications to advocacy groups and patient participants.

TRIAL REGISTRATION

NCT02810704.

12-month post-trial follow-up of participants in the Australian arm of the second low-dose colchicine trial

Background

In the Australian arm of the LoDoCo2 trial, colchicine 0.5mg daily compared with placebo markedly reduced the risk of cardiovascular (CV) events in patients with chronic coronary disease (2.0 vs 3.9 events per 100 person years, HR 0.51; 95% CI 0.39–0.67). The purpose of this analysis was to explore CV and non-CV outcomes in the Australian cohort out to one year after cessation of trial medication.

Methods

Information was collected on all potential CV events and non-CV deaths as well as a range of other co-morbidities. All CV events were blindly adjudicated. The analysis examined the primary outcome (a composite of CV death, myocardial infarction, ischemic stroke, and unscheduled revascularization) and non-CV deaths by initial randomized treatment from the beginning of the trial up until one year after cessation of trial medication. A landmark analysis was then used to examine these outcomes from the date of last contact during the trial until one year after cessation of trial medication.

Results

The clinical status was confirmed in 1819/1824 (99.7%) participants who were alive at the end of the trial, and in 100% of those participants still taking trial medication at the end of the trial. During post-trial follow up, 515 patients (28.2%) were taking non-study colchicine, including 278 (30.5%) originally randomized to colchicine and 237 (25.9%) randomized to placebo. Over the entire follow-up period that included the 12-month period after the trial medication was ceased, the effect of prior exposure to colchicine on the primary CV outcome was still evident (2.2 vs 3.8 events per 100 person years, HR 0.58; 95% CI 0.45–0.74), however no post-trial CV benefit were apparent in the landmark analysis (3.3 vs 3.4 events per 100 person years, HR 0.97; 95% CI 0.56–0.1.69). Over the entire course of follow-up the incidence of new cancer (7.9% vs 7.2% RR 0.91; 95% CI 0.66–1.25) and non-CV death (0.9 vs 0.6 events per 100 person years, HR 1.44; 95% CI 0.92–2.27) was no different in the treatment groups.

Conclusion

Although the CV benefits of colchicine treatment that emerged during the trial were still evident in the year after stopping study treatment, no additional CV benefit accrued after it was ceased. These data suggest that colchicine should be continued long-term to maximize its CV benefits.

Funding Acknowledgement

Type of funding sources: None.

Evaluation of the prognostic value of GDF-15, ABC-AF-bleeding score and ABC-AF-death score in patients with atrial fibrillation across different geographical areas

Objectives

Growth differentiation factor 15 (GDF-15) is a biomarker independently associated with bleeding and death in anticoagulated patients with atrial fibrillation (AF). GDF-15 is also used as one component in the more precise biomarker-based ABC (age, biomarkers, clinical history)-AF-bleeding and ABC-AF-death risk scores. Data from large trials indicate a geographic variability in regard to overall outcomes, including bleeding and mortality risk. Our aim was to assess the consistency of the association between GDF-15, ABC-AF-bleeding score and ABC-AF-death score, with major bleeding and death, across world geographic regions.

Methods

Data were available from 14 767 patients with AF from the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) trial and 8651 patients with AF from the Randomized Evaluation of Long-Term Anticoagulation Therapy (RE-LY) trial in this cohort study. GDF-15 was analysed from plasma samples obtained at randomisation. The geographical consistency of the associations between outcomes and GDF-15, ABC-AF-bleeding score and ABC-AF-death scores were assessed by Cox-regression models including interactions with predefined geographical region.

Results

GDF-15 and the ABC-AF-bleeding score were associated with major bleeding in both trials across regions (p<0.0001). Similarly, GDF-15 and the ABC-AF-death score were associated with all-cause mortality in both trials across regions (p<0.0001). Overall, the association between GDF-15, the ABC-AF-bleeding score and ABC-AF-death risk score with major bleeding and death was consistent across regions in both ARISTOTLE and the RE-LY trial cohorts. The ABC-AF-bleeding and ABC-AF-death risk scores were consistent regarding discriminative ability when comparing geographic regions in both trial cohorts. The C-indices ranged from 0.649 to 0.760 for the ABC-AF-bleeding and from 0.677 to 0.806 for the ABC-AF-death score by different geographic regions.

Conclusions

In patients with AF on anticoagulation, GDF-15 and the biomarker-based ABC-AF-bleeding and ABC-AF-death risk scores are consistently associated with respectively increased risk of major bleeding and death and have similar prognostic value across world geographic regions.

Trial registration number

ClinicalTrials.gov Registry NCT00412984 and NCT00262600.

A Novel Model for Prediction of Thromboembolic and Cardiovascular Events in Patients Without Atrial Fibrillation

Patients without atrial fibrillation (AF) constitute approximately 75% of patients suffering thromboembolism and major adverse cardiovascular events (MACE), but evidence supporting risk stratification in these patients is sparse. We aimed to develop a risk prediction model for identification of patients without AF at high risk of first-time thromboembolic events. We included 72,381 coronary angiography patients without AF and without previous ischemic stroke or transient ischemic attack. The cohort was randomly divided into a derivation cohort (80%, n = 57,680) and a validation cohort (20%, n = 14,701). The primary thromboembolic end point was a composite of ischemic stroke, transient ischemic attack, and systemic embolism. MACE was defined as a composite of cardiac death, myocardial infarction, and ischemic stroke. The final model was compared with 2 validated clinical risk models (CHADS₂ and CHA₂DS₂-VASc). The risk prediction model assigned 1 point to heart failure, hypertension, diabetes mellitus, renal disease, age 65 to 74 years, active smoking, and multivessel obstructive coronary artery disease, and 2 points to age ≥75 years and peripheral artery disease. A C-index of 0.66 (95% CI 0.64 to 0.69) for prediction of the composite thromboembolic end point was found in the validation cohort, which was higher than for CHADS₂ (C-index 0.63 [95% CI 0.60 to 0.67]; p < 0.001) and CHA₂DS₂-VASc (C-index 0.64 [95% CI 0.62 to 0.67]; p = 0.034). The model also predicted MACE (C-index 0.71 [95% CI 0.69 to 0.73]). In conclusion it is possible to identify patients without AF at high risk of first-time thromboembolic events and MACE by use of a simple clinical prediction model.

2180Estimating individual lifetime benefit and bleeding risk of adding rivaroxaban to aspirin for patients with stable cardiovascular disease: results from the COMPASS trial

Background

The Cardiovascular Outcomes for People Using Anticoagulation Strategies (COMPASS) trial has demonstrated that adding low-dose rivaroxaban to aspirin in patients with stable atherosclerotic disease on average reduces recurrence of cardiovascular disease (CVD) events, but increases the risk of major bleeding. For clinical practice, it is important to be able to weigh the absolute benefit from the intervention in terms of lower cardiovascular risk against the absolute increase in risk for major bleeding.

Purpose

The aim of this study was to estimate the individual lifetime benefit and harm of adding low-dose rivaroxaban to aspirin in patients with stable cardiovascular disease by predicting individual months free from CVD events gained and individual months free from major bleeding lost.

Methods

Analyses were based on data of patients with established CVD in the COMPASS trial (n=27,390) and SMART prospective cohort study (n=8,139). The externally validated lifetime SMART-REACH model for recurrent CVD was used to predict life expectancy free of stroke and myocardial infarction, based on the following predictors: sex, current smoking, diabetes mellitus, systolic blood pressure, total cholesterol, creatinine, number of locations of CVD, history of atrial fibrillation, and history of congestive heart failure. A new Fine & Gray competing-risk adjusted Cox proportional hazard model was derived in the COMPASS study population for prediction of life expectancy free from major bleeding, including the same predictors as the SMART-REACH model and additionally ethnicity, geographical region, and history of bleeding requiring transfusion. These lifetime estimates were then combined with hazard ratios from the COMPASS trial to estimate lifetime treatment effects from adding low-dose rivaroxaban to aspirin, expressed in terms of 1) months free from stroke or myocardial infarction gained, and 2) months free from major bleeding lost.

Results

External goodness-of-fit of the SMART-REACH model in the COMPASS study was sufficient. The newly developed major bleeding risk model also showed sufficient external goodness-of-fit in the SMART cohort. The median predicted individual gain in life-expectancy free of stroke or MI from added low-dose rivaroxaban was 16 months (range 1–48 months), while the median predicted individualized lifetime lost in terms of major bleeding was 2 months (range 0–20 months) (Figure 1A). Predicted benefit was higher than predicted harm in more than 90% of the study population. An interactive calculator for use in clinical practice will be made available (example in figure 1B).

Figure 1

Conclusions

There is a wide distribution in lifetime gain and harm from adding low-dose rivaroxaban to aspirin in individual patients with stable CVD. Using these lifetime models, benefits and bleeding risk can be weighed for and with each individual patient, to support treatment decision making in clinical practice.

288Thrombotic events in bleeding patients treated with andexanet alpha: an ANNEXA-4 sub-study

Background/Introduction

Andexanet alfa (“andexanet”) was developed as a specific reversal agent for patients with major bleeding while using factor Xa (FXa) inhibitors. While thrombotic events (TEs) have been reported in patients receiving andexanet, the scope, nature, and timing of these events have not been fully characterized.

Purpose

The ANNEXA-4 study was a prospective, single-arm, open-label clinical trial that evaluated the safety and efficacy of andexanet in patients with acute major bleeding. In this secondary analysis, the occurrence of TEs was investigated.

Methods

Patients presenting with acute major bleeding within 18 hours after their last dose of FXa inhibitor were treated with andexanet. Safety outcomes, including TEs (reviewed by an adjudication committee), were evaluated at 30 days.

Results

Among 352 patients treated with andexanet, 34 (9.7%) experienced one or more TEs (Table). Strokes and deep vein thromboses were the most frequent TE types. Compared to patients with arterial TEs, patients with venous TEs were more likely to have been originally anticoagulated for venous thromboembolism. Median time to first TE was 10.5 days (Figure); time to event was shorter for arterial TEs than for venous TEs. TEs were nonfatal for most patients. Subgroups by age, bleed type, baseline anti-fXa activity, FXa inhibitor dose, and andexanet dose were not associated with the occurrence of TEs. Of the 34 TE patients, 26 (76.4%) had TEs before restart of any (full or prophylactic) anticoagulation; all first TEs occurred in patients not receiving oral anticoagulation. No TEs occurred after resumption of oral anticoagulation (N=100).

Table 1. Thrombotic event characteristics Characteristic Result (n/N [%]) TE type   Strokes 14/352 (4.0%)   Deep vein thromboses 13/352 (3.7%)   Myocardial infarctions 7/352 (2.0%)   Pulmonary embolisms 5/352 (1.4%)   Transient ischemic attacks 1/352 (0.3%) Bleed type   Intracranial 23/227 (10.1%)   Gastrointestinal 7/90 (7.8%)   Other 4/35 (11.4%) Arterial TEs   Anticoagulated for AF 17/22 (77.3%)   Anticoagulated for VTE 6/22 (27.3%) Venous TEs   Anticoagulated for AF 11/18 (61.1%)   Anticoagulated for VTE 8/18 (44.4%)   Median time to first TE 10.5 days   Arterial 6 days   Venous 15 days Outcome   Fatal 7/34 (20.6%)   Nonfatal 27/34 (79.4%) AF = atrial fibrillation; n = number of patients with TEs; N = total number of patients for each characteristic; TE = thrombotic event; VTE = venous thromboembolism.

Figure 1. Thrombotic Events Over Time

Conclusions

In patients with FXa inhibitor-associated acute major bleeding treated with andexanet, TEs occurred a rate not unexpected given the high thrombotic risk of the population. No factors predictive of TEs were identified. Resumption of anticoagulation was associated with fewer TEs.

Acknowledgement/Funding

Study funded by Portola Pharmaceuticals, Inc.

287Diabetes mellitus is a risk factor for ischemic stroke in patients with and without coronary artery disease after coronary angiography

Background

Diabetes (DM) and non-DM patients without coronary artery disease (CAD) by coronary angiography (CAG) have the same low risk of myocardial infarction.

Purpose

To study whether DM patients without CAD have the same risk of ischemic stroke as patients with neither DM nor CAD.

Methods

We conducted a cohort study of patients, who underwent CAG between 2004 and 2012 in the Western Denmark Heart Registry. Patients previously diagnosed with ischemic stroke or atrial fibrillation (AF) and those treated with an oral anticoagulant were excluded. Patients were stratified according to presence of DM and CAD. Follow-up started 30 days after CAG. We computed event rates and adjusted incidence rate ratios (IRRs) using patients with neither DM nor CAD as reference.

Results

A total of 68,829 patients were included. Median follow-up was 4.0 years. Patients with both DM and CAD were at the highest risk of ischemic stroke (1.25 events per 100 person-years; adjusted IRR 2.10, 95% CI 1.77–2.48) (Figure 1). Patients with CAD alone (0.70 events per 100 person-years; adjusted IRR 1.29, 95% CI 1.12–1.48) or DM alone (0.84 events per 100 person-years; adjusted IRR 1.79, 95% CI 1.41–2.26) were at intermediate risk while patients with neither DM nor CAD (0.46 events per 100 person-years) were at lowest risk. Among DM patients, extent of CAD was further predictive of risk (ptrend<0.001).

Figure 1

Conclusions

Not only CAD but also DM independently predict the risk of ischemic stroke after CAG. Their combination further increases the risk of ischemic stroke depending on the extent of CAD.

P1527The applicability of the dual pathway approach criteria after coronary angiography

Background

The combination of aspirin and low-dose rivaroxaban (dual pathway approach, DPA) has been approved for high-risk patients with stable coronary artery disease (CAD) in the COMPASS trial. Patients with CAD combined with ≥1 DPA criteria, defined as peripheral artery disease, renal failure, heart failure, or diabetes, have been proposed as high-risk patients eligible for DPA.

Purpose

To determine the prevalence of patients meeting the DPA criteria and the association with major adverse cardiovascular events (MACE) in patients with stable CAD after coronary angiography (CAG). Further, to evaluate use of the DPA criteria in CAD patients meeting the inclusion criteria in the COMPASS trial.

Methods

We studied patients included in the Western Denmark Heart Registry after examination by CAD 2004–11. Patients without CAD or myocardial infarction (MI) <1 year before or 30 days after CAG were excluded. Patients were stratified according to 0 or ≥1 DPA criteria and being eligible/ineligible for the COMPASS trial. Event rates and incidence rate ratios (IRRs) of MACE (cardiac death, ischemic stroke, and MI) were estimated.

Results

Of 80,071 patients undergoing CAG, 18,689 (23%) patients had stable CAD. According to the DPA criteria, 7,730 patients (10%) were DPA eligible. Rates of MACE were 1.98 (95% CI 1.86–2.34) events per 100 person-years among DPA ineligible patients and 4.26 (95% CI 4.04–4.50) events per 100 person-years among DPA eligible patients (IRR 2.15, 95% CI 1.98–2.34). When stratifying patients according to eligibility in the COMPASS inclusion criteria, COMPASS eligible patients with 0 DPA criteria and COMPASS ineligible patients with ≥1 DPA criteria were at intermediate risk compared to patients meeting both (high risk) or none (low risk) of these criteria (Figure 1).

Figure 1

Conclusion

In a cohort of consecutive patients undergoing CAG, 1 in 10 patients would be eligible for DPA according to the DPA criteria. Patients with stable CAD and ≥1 DPA criteria had >2-fold higher rate of MACE than CAD patients without any DPA criteria.

Comparison of bleeding risk scores in patients with atrial fibrillation: insights from the RE-LY trial

BACKGROUND

Oral anticoagulation is the mainstay of stroke prevention in atrial fibrillation (AF), but must be balanced against the associated bleeding risk. Several risk scores have been proposed for prediction of bleeding events in patients with AF.

OBJECTIVES

To compare the performance of contemporary clinical bleeding risk scores in 18 113 patients with AF randomized to dabigatran 110 mg, 150 mg or warfarin in the RE-LY trial.

METHODS

HAS-BLED, ORBIT, ATRIA and HEMORR₂ HAGES bleeding risk scores were calculated based on clinical information at baseline. All major bleeding events were centrally adjudicated.

RESULTS

There were 1182 (6.5%) major bleeding events during a median follow-up of 2.0 years. For all the four schemes, high-risk subgroups had higher risk of major bleeding (all P < 0.001). The ORBIT score showed the best discrimination with c-indices of 0.66, 0.66 and 0.62, respectively, for major, life-threatening and intracranial bleeding, which were significantly better than for the HAS-BLED score (difference in c-indices: 0.050, 0.053 and 0.048, respectively, all P < 0.05). The ORBIT score also showed the best calibration compared with previous data. Significant treatment interactions between the bleeding scores and the risk of major bleeding with dabigatran 150 mg BD versus warfarin were found for the ORBIT (P = 0.0019), ATRIA (P < 0.001) and HEMORR₂ HAGES (P < 0.001) scores. HAS-BLED score showed a nonsignificant trend for interaction (P = 0.0607).

CONCLUSIONS

Amongst the current clinical bleeding risk scores, the ORBIT score demonstrated the best discrimination and calibration. All the scores demonstrated, to a variable extent, an interaction with bleeding risk associated with dabigatran or warfarin.

Atherothrombosis and Thromboembolism: Position Paper from the Second Maastricht Consensus Conference on Thrombosis

Atherothrombosis is a leading cause of cardiovascular mortality and long-term morbidity. Platelets and coagulation proteases, interacting with circulating cells and in different vascular beds, modify several complex pathologies including atherosclerosis. In the second Maastricht Consensus Conference on Thrombosis, this theme was addressed by diverse scientists from bench to bedside. All presentations were discussed with audience members and the results of these discussions were incorporated in the final document that presents a state-of-the-art reflection of expert opinions and consensus recommendations regarding the following five topics: 1. Risk factors, biomarkers and plaque instability: In atherothrombosis research, more focus on the contribution of specific risk factors like ectopic fat needs to be considered; definitions of atherothrombosis are important distinguishing different phases of disease, including plaque (in)stability; proteomic and metabolomics data are to be added to genetic information. 2. Circulating cells including platelets and atherothrombosis: Mechanisms of leukocyte and macrophage plasticity, migration, and transformation in murine atherosclerosis need to be considered; disease mechanism-based biomarkers need to be identified; experimental systems are needed that incorporate whole-blood flow to understand how red blood cells influence thrombus formation and stability; knowledge on platelet heterogeneity and priming conditions needs to be translated toward the in vivo situation. 3. Coagulation proteases, fibrin(ogen) and thrombus formation: The role of factor (F) XI in thrombosis including the lower margins of this factor related to safe and effective antithrombotic therapy needs to be established; FXI is a key regulator in linking platelets, thrombin generation, and inflammatory mechanisms in a renin-angiotensin dependent manner; however, the impact on thrombin-dependent PAR signaling needs further study; the fundamental mechanisms in FXIII biology and biochemistry and its impact on thrombus biophysical characteristics need to be explored; the interactions of red cells and fibrin formation and its consequences for thrombus formation and lysis need to be addressed. Platelet-fibrin interactions are pivotal determinants of clot formation and stability with potential therapeutic consequences. 4. Preventive and acute treatment of atherothrombosis and arterial embolism; novel ways and tailoring? The role of protease-activated receptor (PAR)-4 vis à vis PAR-1 as target for antithrombotic therapy merits study; ongoing trials on platelet function test-based antiplatelet therapy adjustment support development of practically feasible tests; risk scores for patients with atrial fibrillation need refinement, taking new biomarkers including coagulation into account; risk scores that consider organ system differences in bleeding may have added value; all forms of oral anticoagulant treatment require better organization, including education and emergency access; laboratory testing still needs rapidly available sensitive tests with short turnaround time. 5. Pleiotropy of coagulation proteases, thrombus resolution and ischaemia-reperfusion: Biobanks specifically for thrombus storage and analysis are needed; further studies on novel modified activated protein C-based agents are required including its cytoprotective properties; new avenues for optimizing treatment of patients with ischaemic stroke are needed, also including novel agents that modify fibrinolytic activity (aimed at plasminogen activator inhibitor-1 and thrombin activatable fibrinolysis inhibitor.

Emergency care of patients receiving non-vitamin K antagonist oral anticoagulants

Non-vitamin K antagonist oral anticoagulants (NOACs), which inhibit thrombin (dabigatran) and factor Xa (rivaroxaban, apixaban, edoxaban) have been introduced in several clinical indications. Although NOACs have a favourable benefit-risk profile and can be used without routine laboratory monitoring, they are associated-as any anticoagulant-with a risk of bleeding. In addition, treatment may need to be interrupted in patients who need surgery or other procedures. The objective of this article, developed by a multidisciplinary panel of experts in thrombosis and haemostasis, is to provide an update on the management of NOAC-treated patients who experience a bleeding episode or require an urgent procedure. Recent advances in the development of targeted reversal agents are expected to help streamline the management of NOAC-treated patients in whom rapid reversal of anticoagulation is required.

Comparison of the ecarin chromogenic assay and diluted thrombin time for quantification of dabigatran concentrations

Essentials Routine monitoring is unnecessary but measuring dabigatran levels is helpful in certain situations. We compared ecarin chromogenic assay (STA-ECA-II) and dilute thrombin time (dTT) in patient samples. Both tests provided accurate measurements over a wide range of dabigatran concentrations. Adoption of STA-ECA-II and dTT into routine clinical practice will improve patient care.

SUMMARY

Background Although routine coagulation monitoring is unnecessary, measuring plasma dabigatran concentrations can be useful for detecting drug accumulation in renal failure or overdose, assessing the contribution of dabigatran to serious bleeding, planning the timing of urgent surgery or intervention, or determining the suitability for thrombolytic therapy for acute ischemic stroke. Dabigatran concentrations can be quantified using chromogenic or clot-based tests, such as the ecarin chromogenic assay (ECA) and the diluted thrombin time (dTT), respectively. Objective The purpose of this study was to compare the results of these assays with dabigatran concentrations measured by the reference standard of mass spectrometry in samples from 50 dabigatran-treated patients collected at peak and trough after at least 4 months of drug intake. Methods Drug levels measured with either the STA Ecarin Chromogenic Assay-II (STA-ECA-II) or dTT were linearly correlated with those determined by mass spectrometry over a wide range of concentrations. Results and Conclusions For detection of levels below 50 ng mL-1 both tests have specificities of at least 96%, suggesting that they accurately detect even low levels of drug. Therefore, regardless of whether a chromogenic or clot-based platform is preferred, the STA-ECA-II and dTT are useful tests for measuring dabigatran concentrations. Unfortunately, neither test is licensed by the United States Food and Drug Administration. Although approved in other jurisdictions, the dTT and STA-ECA-II are not widely or rapidly available in most hospitals. Therefore, cooperation between regulators and hospitals is urgently needed to render these tests readily available to inform patient care.

Once versus twice daily aspirin after coronary bypass surgery: a randomized trial

Essentials Coronary artery bypass graft (CABG) failure is associated with myocardial infarction and death. We tested whether more frequent dosing improves aspirin (ASA) response following CABG surgery. Twice-daily compared with once-daily dosing reduces ASA hyporesponsiveness after CABG surgery. The efficacy of twice-daily ASA needs to be tested in a trial powered for clinical outcomes.

SUMMARY

Background Acetyl-salicylic acid (ASA) hyporesponsiveness occurs transiently after coronary artery bypass graft (CABG) surgery and may compromise the effectiveness of ASA in reducing thrombotic graft failure. A reduced response to ASA 81 mg once-daily after CABG surgery is overcome by four times daily ASA dosing. Objectives To determine whether ASA 325 mg once-daily or 162 mg twice-daily overcomes a reduced response to ASA 81 mg once-daily after CABG surgery. Methods Adults undergoing CABG surgery were randomized to ASA 81 mg once-daily, 325 mg once-daily or 162 mg twice-daily. The primary outcome was median serum thromboxane B2 (TXB2 ) level on postoperative day 4. We pooled the results with those of our earlier study to obtain better estimates of the effect of ASA 325 mg once-daily or in divided doses over 24 h. Results We randomized 68 patients undergoing CABG surgery. On postoperative day 4, patients randomized to receive ASA 81 mg once-daily had a median day 4 TXB2 level of 4.2 ng mL-1 (Q1, Q3: 1.5, 7.5 ng mL-1 ), which was higher than in those randomized to ASA 162 mg twice-daily (1.1 ng mL-1 ; Q1, Q3: 0.7, 2.7 ng mL-1 ) and similar to those randomized to ASA 325 mg once-daily (1.9 ng mL-1 ; Q1, Q3: 0.9, 4.7 ng mL-1 ). Pooled data showed that the median TXB2 level on day 4 in groups receiving ASA 162 mg twice-daily or 81 mg four times daily was 1.1 ng mL-1 compared with 2.2 ng mL-1 in those receiving ASA 325 mg once-daily. Conclusions Multiple daily dosing of ASA is more effective than ASA 81 mg once-daily or 325 mg once-daily at suppressing serum TXB2 formation after CABG surgery. A twice-daily treatment regimen needs to be tested in a clinical outcome study.

Mortality outcomes in patients transfused with fresher versus older red blood cells: a meta-analysis

BACKGROUND

Among transfused patients, the effect of the duration of red blood cell storage on mortality remains unclear. This study aims to compare the mortality of patients who were transfused with fresher versus older red blood cells.

METHODS

We performed an updated systematic search in the CENTRAL, MEDLINE, EMBASE and CINAHL databases, from January 2015 to October 2016. RCTs of hospitalized patients of any age comparing transfusion of fresher versus older red blood cells were eligible. We used a random-effects model to calculate pooled risk ratios (RRs) with corresponding 95% confidence interval (CI).

RESULTS

We identified 14 randomized trials that enrolled 26 374 participants. All-cause mortality occurred in 1219 of 9531 (12·8%) patients who received a transfusion of fresher red blood cells and 1810 of 16 843 (10·7%) in those who received older red blood cells (RR: 1·04, 95% CI: 0·98-1·12, P = 0·90, I² = 0%, high certainty for ruling out benefit of fresh blood, moderate certainty for ruling out harm of fresh blood). In six studies, in-hospital death occurred in 691 of 7479 (9·2%) patients receiving fresher red cells and 1291 of 14 757 (8·8%) receiving older red cells (RR: 1·06, 95% CI: 0·97-1·15, P = 0·81, I² = 0%, high certainty for ruling out benefit of fresh blood, moderate certainty for ruling out harm of fresh blood).

CONCLUSION

Transfusion of fresher red blood cells does not reduce overall or in-hospital mortality when compared with older red blood cells. Our results support the practice of transfusing patients with the oldest red blood cells available in the blood bank.

Effect of standardized perioperative dabigatran interruption on the residual anticoagulation effect at the time of surgery or procedure

ESSENTIALS: Anticoagulants need to be stopped preprocedure so there is little or no remaining anticoagulant effect. We assessed the residual anticoagulant effect with standardized interruption for patients on dabigatran. With this protocol, 80-86% of patients had no residual anticoagulant effect at the time of a procedure. A standardized perioperative dabigatran protocol appears to be safe, but requires further study.

BACKGROUND

In patients taking dabigatran who require treatment interruption for a surgery/procedure, a sufficient interruption interval is needed so that there is little or no residual anticoagulant effect at the time of the surgery/procedure.

METHODS

A prospective cohort study of patients receiving dabigatran (110 mg or 150 mg twice daily) who required an elective surgery/procedure and received a standardized dabigatran interruption protocol based on surgery/procedure bleeding risk and renal function was performed. Before the surgery/procedure, a blood sample was taken for measurement of the prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), and dilute thrombin time (dTT). We determined the proportion of all patients and those having a high bleeding risk surgery/procedure with normal coagulation test results at the time of the surgery/procedure. The APTT and dTT were considered to be most likely to reflect a dabigatran anticoagulant effect. Patients were followed up for 30 days postprocedure to assess for bleeding and thromboembolism.

RESULTS

One hundred and eighty-one patients were studied: 118 with low bleeding risk, and 63 with high bleeding risk. For all patients, the proportions with normal PT, APTT, TT dTT levels were 92.8%, 79.6%, 33.1%, and 80.7%, respectively. In patients with high bleeding risk, the proportions with normal PT, APTT, TT dTT levels were 93.7%, 85.7%, 57.1%, and 87.3%, respectively. During follow-up, there was one (0.6%) major bleed, there were nine (5.0%) minor bleeds, and there was one (0.6%) transient ischemic attack.

CONCLUSIONS

In patients receiving dabigatran who require an elective surgery/procedure, a standardized interruption protocol yielded 80-86% of patients with no residual anticoagulant effect at the time of surgery/procedure, and with a low incidence of bleeding.

Management of bleeding with oral anticoagulants in patients with atrial fibrillation

Fear of bleeding is a common barrier to the use of anticoagulants. Warfarin has been the only oral anticoagulant for more than 60 years and warfarin-related bleeding is reported to be the most common drug-related cause of emergency hospitalization in elderly Americans. Non-vitamin K oral antagonists were introduced five years ago and compared with warfarin are associated with lower risk of intracranial bleeding, and similar or lower case fatality after major bleeding. Despite their superior safety profile, serious bleeding can occur. Most bleeding can be managed with holding the drug, local measures to control the bleeding and transfusion support as required because the NOACs have a relatively short half life and their anticoagulant effect rapidly dissipates. In patients with ongoing bleeding despite supportive measures and in those with life-threatening bleeding, consideration may be given to the use of general hemostatic agents. Experimental and animal evidence suggests that 3 and 4 factor prothrombin complex concentrates can improve hemostasis in the presence of a NOAC and this is reinforced by anecdotal evidence in humans. Specific antidotes are currently in phase 3 trials and could become available in the near future.

Real-world variability in dabigatran levels in patients with atrial fibrillation

BACKGROUND

In clinical practice, physicians are given the choice of selecting one of two dabigatran doses based on patient characteristics, with the lower dose typically used in patients at a higher risk of bleeding.

OBJECTIVES

The objectives of the study were to (i) estimate the inter- and intra-patient variability in dabigatran levels with 110 mg (DE110) and 150 mg (DE150) doses, (ii) examine the effect of physicians' dose selection on levels in DE110 and DE150 subgroups, and (iii) explore whether a single trough measurement identifies patients with extreme levels on subsequent visits.

METHODS

In this prospective observational study of 100 patients with atrial fibrillation (AF), peak and trough levels of dabigatran were measured with the Hemoclot(®) assay at baseline and every 2 months thereafter (maximum four visits).

RESULTS

Inter-patient variability in dabigatran levels (geometric coefficient of variation [gCV], 51-64%) was greater than intra-patient variability (gCV, 32-40%). Similar medians and distributions of levels were observed in DE110 and DE150 subgroups. Patients receiving DE110 were older, had lower renal function and weighed less than those receiving DE150. Up to 40% of patients whose trough levels were in the upper extremes, and up to 80% of patients whose trough levels were in the lower extremes at baseline, showed subsequent levels that fell in the middle quartiles.

CONCLUSIONS

Our data support the practice of selecting the dabigatran dose based upon clinical characteristics because it results in similar levels of drug exposure in patients given DE110 or DE150. They do not support the concept that a single Hemoclot(®) measurement reliably identifies patients with consistently high or low values.

Multiple daily doses of acetyl-salicylic acid (ASA) overcome reduced platelet response to once-daily ASA after coronary artery bypass graft surgery: a pilot randomized controlled trial

BACKGROUND

The efficacy of ASA for prevention of graft failure following CABG surgery may be limited by incomplete platelet inhibition due to increased post-operative platelet turnover.

OBJECTIVES

To determine whether acetyl-salicylic acid (ASA) 325 mg once-daily or 81 mg four-times daily overcomes the impaired response to ASA 81 mg once-daily in post-operative coronary artery bypass graft (CABG) patients.

METHODS

We randomized 110 patients undergoing CABG surgery to either ASA 81 mg once-daily, 81 mg four times daily or 325 mg once-daily and compared their effects on serum thromboxane B2 (TXB2 ) suppression and arachidonate-induced platelet aggregation.

RESULTS

One hundred patients were included in the final analysis. Platelet counts fell after surgery, reached a nadir on day 2, and then gradually increased. Although there was near complete suppression of TXB2 on the second or third post-operative day, TXB2 levels increased in parallel with the rise in platelet count on subsequent days. This increase was most marked in patients receiving ASA 81 mg once-daily and less evident in those receiving ASA four times daily. On post-operative day 4, (i) median TXB2 levels were lower with four times daily ASA than with either ASA 81 mg once-daily (1.1 ng/mL; Quartile(Q) Q1,Q3: 0.5, 2.4 and 13.3 ng/mL; Q1,Q3: 7.8, 30.8 ng/mL, respectively; P < 0.0001) or ASA 325 mg once-daily (3.4 ng/mL; Q1,Q3: 2.0, 8.2 ng/mL; P = 0.002), and (ii) ASA given four times daily was more effective than ASA 81 mg once-daily and 325 mg once-daily at suppressing platelet aggregation.

CONCLUSIONS

Four times daily ASA is more effective than ASA 81 and 325 mg once-daily at suppressing serum TXB2 formation and platelet aggregation immediately following CABG surgery.

Active metabolite concentration of clopidogrel in patients taking different doses of aspirin: results of the interaction trial

BACKGROUND

The CURRENT-OASIS-7 and PLATO trials suggest that the benefit of clopidogrel is influenced by the dose of aspirin.

OBJECTIVE

To explore a potential pharmacokinetic interaction between aspirin and clopidogrel, and determinants of clopidogrel active metabolite (AM) levels.

METHODS

In part 1, using a 2 × 2 factorial design, we randomized patients to clopidogrel 600 mg loading dose (LD) followed by 150 mg day(-1) for 6 days and 75 mg day(-1) thereafter, or clopidogrel 300 mg LD followed by 75 mg day(-1) thereafter, and compared aspirin at 325 mg or 81 mg day(-1) . In part 2, patients were given a 600-mg clopidogrel LD, and were randomly allocated to aspirin 325 mg or 81 mg day(-1) . We combine the data from the two parts. Blood samples were collected 1 h after administration of the study drug.

RESULTS

We randomized 302 patients (mean age 60.4 ± 9.9 years). Clopidogrel AM levels were similar in patients randomized to aspirin 325 or 81 mg (geometric mean, 12.70 ng mL(-1) ; 95% CI, 10.96-14.72 ng mL(-1) ; and geometric mean, 12.55 ng mL(-1) ; 95% CI, 10.80-14.58 ng mL(-1) ; P = 0.91). Blood levels of clopidogrel were lower in CYP2C19*2 loss-of-function (LOF) carriers compared with non-carriers (10.72 ng mL(-1) ; 95% CI, 8.83-13.01 ng mL(-1) ; and 15.21 ng mL(-1) ; 95% CI, 13.30-17.40 ng mL(-1) , respectively; P = 0.003) whereas levels in gain of function carriers and non-carriers were similar (13.31 ng mL(-1) ; 95% CI, 11.53-15.35 ng mL(-1) ; and 14.07 ng mL(-1) ; 95% CI, 11.74-16.87 ng mL(-1) , respectively; P = 0.4). Independent baseline predictors of clopidogrel AM levels were LOF genotype, body mass index, diabetes, proton pump inhibitor use and creatinine clearance, but accounted for only 20% of the variability in levels.

CONCLUSION

Aspirin dose does not predict clopidogrel AM levels 1 h post-LD. Most of the variability in clopidogrel AM levels is not explained by patient characteristics or CYP2C19 metabolizer status.

Comparison of the effects of apixaban and rivaroxaban on prothrombin and activated partial thromboplastin times using various reagents

BACKGROUND

Clinical situations occur where expedient assessment of the anticoagulant activity of the direct factor Xa (FXa) inhibitors is required. Although quantitative anti-FXa (FXa) assays can be used to measure plasma levels of apixaban or rivaroxaban, turnaround is often slow and many laboratories do not perform these assays.

OBJECTIVE

We compared the in vitro effects of apixaban and rivaroxaban on two readily available laboratory tests, the prothrombin time (PT) and activated partial thromboplastin time (APTT), performed with different reagents. We aimed to identify the most sensitive reagents.

METHODS

Rivaroxaban or apixaban was added to human plasma at a range of concentrations covering expected peak and trough levels, and concentrations were confirmed using calibrated anti-FXa assays. Samples were assayed with six PT and seven APTT reagents using different coagulometers.

RESULTS AND CONCLUSIONS

TriniCLOT PT Excel S was the only reagent to demonstrate sensitivity to apixaban. All of the PT reagents were sensitive to rivaroxaban with TriniCLOT PT Excel S and HemosIL HS PLUS being the most sensitive. Sensitivity to rivaroxaban varied among APTT reagents; four reagents exhibited the greatest responsiveness, and of these, Actin FSL was the most responsive. Commonly used coagulation tests may be useful for assessing the anticoagulant effect of rivaroxaban but not of apixaban. The reason for the different effects of apixaban and rivaroxaban on the PT and APTT is unknown.

Loading dose vs. maintenance dose of warfarin for reinitiation after invasive procedures: a randomized trial

BACKGROUND

There is uncertainty regarding the optimal dosing regimen for the resumption of warfarin after interruption for invasive procedures.

AIM

To determine the efficacy and safety of warfarin resumption with loading doses or with the most recent maintenance dose.

METHODS

Patients receiving warfarin treatment and planned for invasive procedures with an expected hospital stay of ≤ 1 day were randomized to resume warfarin on the day of the procedure, defined as day 1, with most recent maintenance dose or with 2 initial days of double maintenance dose. Efficacy outcomes were proportion of international normalized ratio (INR) levels ≥ 2.0 on day 5 (primary outcome) and day 10. Safety outcomes were bleeding and thromboembolic events. In addition, D-dimer levels were analyzed on days 5 and 10 in a subset of the population.

RESULTS

There were 49 patients analyzed in each group. INR of ≥ 2.0 had been achieved by day 5 for 13% in the maintenance-dose group and for 50% in the loading-dose group (relative risk [RR] 0.27, 95% confidence interval [CI] 0.10-0.60) and by day 10 for 68% and 87%, respectively (RR 0.78, 95% CI 0.65-1.00). There were no thromboembolic events, and there was one major bleed before resumption of warfarin and one minor bleed, both in the maintenance-dose group. There was no difference between the groups in the proportion of patients with excessive INRs or elevated D-dimer levels or in the median D-dimer level.

CONCLUSION

Resumption of warfarin after minor-moderately invasive procedures with two loading doses achieves therapeutic INR faster than does only maintenance dose.

A guide to GRADE guidelines for the readers of JTH

More than 70 organizations worldwide have adopted the GRADE methodology for guideline development. The ninth iteration of the American Collage of Chest Physicians guidelines (AT9) adopted structural and policy changes that resulted in a greater adherence to GRADE guidance than previous iterations. The most important of these changes include minimizing the impact of financial and intellectual conflict of interest, increasing the rigor of evidence evaluation, acknowledging uncertainty in estimates of typical values and preferences, and awareness of the large variability in values and preferences. One of the consequences of the greater adherence to GRADE methodology is an increase in weak vs. strong recommendations in AT9. The result of the GRADE process highlights the desirability of higher-quality evidence both regarding the outcomes of alternative management strategies and regarding the distribution of values and preferences in patients considering those alternatives. It also encourages shared decision making in encounters between physicians and patients. Although some physicians might find the uncertainty underlying medical practice discouraging or unsettling, relative to denying or obscuring the uncertainty, acknowledging and addressing the uncertainty will lead to more credible, realistic, and useful recommendations.

Adherence to anticoagulant treatment with dabigatran in a real-world setting

BACKGROUND

In clinical trials, adherence to a prescribed regimen with dabigatran was enhanced by frequent follow-up visits and pill counts.

OBJECTIVES

To describe the experience of dabigatran treatment in clinical practice, focusing on adherence.

PATIENTS/METHODS

In a cross-sectional cohort study, we interviewed 103 patients treated for at least 3 months with dabigatran and followed by our anticoagulant clinic. We obtained information on the number of capsules of dabigatran dispensed by the pharmacy of each patient covering the entire treatment period and calculated the adherence. In addition, information on the frequency of missed capsules, bleeding, thromboembolic events and other adverse events, specifically dyspepsia, was captured from the interviews and medical records.

RESULTS

The mean age was 75.5 (± 8.5) years, 46% were females, and the mean CHADS2 score was 2.5. Dispensation data were obtained for 99 patients and adherence was 99.7% (median; interquartile range 94.6%-100%) with 11 patients showing < 80% adherence. During their interview, 31 patients (30%) acknowledged that they sometimes had missed taking the medication, ranging from 'twice in 6 years' to 'every day'. One additional patient with adherence < 80% was identified. Twenty-one patients (20%) reported bleeding complications, two of which were major; one patient had an ischemic stroke and 34 (33%) reported some degree of dyspepsia. There were no significant differences in the results between RE-LY study-experienced and study-naïve patients.

CONCLUSION

In our clinical practice adherence to the twice-daily dabigatran regimen was generally good, although 12% of the patients had an inadequate adherence. Routine feedback from the pharmacies could inform the physician to improve the anticoagulant management.

Anti-PF4/heparin antibodies and venous graft occlusion in postcoronary artery bypass surgery patients randomized to postoperative unfractionated heparin or fondaparinux thromboprophylaxis

BACKGROUND

Anti-PF4/heparin antibodies are frequently generated after coronary artery bypass grafting (CABG) surgery, with platelet-activating IgG implicated in heparin-induced thrombocytopenia (HIT). It is controversial whether non-platelet-activating antibodies are associated with thrombosis.

OBJECTIVES

To determine in post-CABG patients whether thromboprophylaxis using fondaparinux vs. unfractionated heparin (UFH) reduces the frequency of anti-PF4/heparin antibodies, and whether anti-PF4/heparin antibodies are associated with early graft occlusion.

METHODS/PATIENTS

In a pre-planned secondary analysis of a randomized control trial (RCT) comparing fondaparinux vs. UFH thromboprophylaxis post-CABG, we determined the frequency of anti-PF4/heparin antibody formation by solid-phase enzyme-immunoassay (EIA) and of platelet-activating antibodies by serotonin-release assay (SRA); the SRA and fluid-phase EIA were used to assess fondaparinux cross-reactivity. We also examined whether anti-PF4/heparin antibodies were associated with early arterial or venous graft occlusion (6-week CT angiography).

RESULTS

We found no significant difference in the frequency of antibody formation between patients who received fondaparinux vs. UFH (65.3% vs. 46.0%; P = 0.069), and no significant fondaparinux cross-reactivity. Venous graft occlusion(s) occurred in 6/26 patients who formed 'strong' IgG antibodies (≥ 1.0 optical density [OD] units and ≥ 2× baseline) vs. 3/66 who did not (P = 0.0139). In both unadjusted and adjusted analyses, strong postoperative (but not pre-operative) anti-PF4/heparin IgG responses were associated with a markedly increased risk of early venous (but not arterial) graft occlusion (adjusted OR, 9.25 [95% CI, 1.73, 49.43]; P = 0.0093); notably, none of the three SRA-positive patients developed a venous graft occlusion.

CONCLUSIONS

Fondaparinux vs. UFH thromboprophylaxis postCABG does not reduce anti-PF4/heparin antibody formation. Non-platelet-activating anti-PF4/heparin IgG antibodies generated post operatively are associated with early venous graft occlusion.

Anticoagulation management in patients with mechanical heart valves having pacemaker or defibrillator insertion

BACKGROUND

In patients with a high risk for stroke and having invasive procedures with a high risk for bleeding it is unclear how anticoagulant therapy should be managed.

METHODS

We reviewed data from all patients with mechanical heart valves, who had elective insertion or replacement of pacemaker or implantable cardioverter defibrillator (ICD) during the past 8years at our hospital. Data on anticoagulant treatment, pocket hematoma and thromboembolic complications were captured.

RESULTS

Of the 111 patients reviewed, 68 (61%) had a mechanical valve in the mitral position with or without other valves replaced and 43 (39%) had a mechanical valve only in the aortic position. Fifty-nine (53%) were undergoing replacement for their device. Six patients received a tapered warfarin regimen and 102 received preoperative bridging anticoagulation of whom 12 also received postoperative bridging. One stroke occurred 40days after pacemaker replacement in a patient with mitral mechanical valve and without postoperative bridging. Six patients (5.5%) developed pocket hematoma without a significant association to postoperative bridging, type of mechanical valve or to type of device. Predictors for pocket hematoma appeared to be replacement surgery (odds ratio 12.5; 95% confidence interval [CI], 0.69-228) and an international normalized ratio of 1.5 or higher on the day of surgery (odds ratio 8.4; 95% CI, 0.96-68.1).

CONCLUSION

We found a low risk for stroke in the absence of postoperative bridging. For patients with device replacement surgery reversal of the anticoagulant effect at the time of procedure might reduce the risk for pocket hematoma, but this requires prospective evaluation including the risk of thromboembolism.

Reversal of the anti-platelet effects of aspirin and clopidogrel

BACKGROUND

Guidelines recommend stopping aspirin and clopidogrel 7 to 10 days before surgery to allow time for replacement of permanently inhibited platelets by newly released uninhibited platelets.

OBJECTIVES

The purpose of the present study was to determine the rate of offset of the anti-platelet effects of aspirin and clopidogrel after stopping treatment and the proportion of untreated donor platelets that are required to reverse their anti-platelet effects.

METHODS

Cohort 1 consisted of 15 healthy subjects who received aspirin 81 mg day(-1) or clopidogrel 75 mg day(-1) for 7 days and underwent serial blood sampling until platelet function testing results normalized. Cohort 2 consisted of 36 healthy subjects who received aspirin 325 mg day(-1), clopidogrel 75 mg day(-1), aspirin 81 mg day(-1) plus clopidogrel 75 mg day(-1) or no treatment for 7 days and underwent a single blood sampling.

RESULTS

In cohort 1, arachidonic acid (AA)-induced light transmission aggregation (LTA) returned to baseline levels in all subjects within 4 days of stopping aspirin, coinciding with the partial recovery of plasma thromboxane B(2) concentrations. ADP-induced LTA did not return to baseline levels until 10 days after stopping clopidogrel. In cohort 2, AA-induced LTA in patient treated with aspirin reached control levels after mixing with 30% untreated donor platelets whereas ADP-induced LTA in patients treated with clopidogrel reached control levels only after the addition of 90% or more donor platelets.

CONCLUSIONS

Platelet aggregation recovers within 4 days of stopping aspirin but clopidogrel must be stopped for 10 days to achieve a normal aggregatory response.

Randomized controlled trial of a new portable calf compression device (Venowave) for prevention of venous thrombosis in high-risk neurosurgical patients

BACKGROUND

Patients undergoing neurosurgical procedures are at risk of venous thromboembolism (VTE), but often have contraindications for anticoagulant prophylaxis.

OBJECTIVES

To assess the efficacy and tolerability of a new, lightweight, portable, battery-powered, intermittent calf compression device, Venowave, for the prevention of VTE in neurosurgical inpatients.

PATIENTS/METHODS

We performed an open randomized controlled trial comparing Venowave with control for the prevention of VTE in patients undergoing neurosurgery. The primary outcome was the composite of asymptomatic deep vein thrombosis (DVT) detected by screening venography or compression ultrasound performed on day 9 (± 2 days) and symptomatic VTE.

RESULTS

We randomized 75 patients to receive Venowave devices and 75 to the control group. All patients were prescribed graduated compression stockings and physiotherapy. VTE occurred in three patients randomized to Venowave and in 14 patients randomized to control (4.0% vs. 18.7%, relative risk 0.21; 95% confidence interval 0.05-0.75, P = 0.008). Similar reductions were seen for proximal DVT (2.7% vs. 8.0%) and symptomatic VTE (0% vs. 2.7%), and the results were consistent in all subgroups examined.

CONCLUSIONS

Venowave devices are effective in preventing VTE in high-risk neurosurgical patients.

Fondaparinux treatment of acute heparin-induced thrombocytopenia confirmed by the serotonin-release assay: a 30-month, 16-patient case series

BACKGROUND

Fondaparinux is theoretically an attractive agent for the treatment of immune heparin-induced thrombocytopenia (HIT), a prothrombotic disorder caused by platelet-activating anti-platelet factor 4/heparin antibodies. Although reports of the use of fondaparinux for this indication have thus far been favorable, the diagnosis of HIT in most cases was not based on definitive laboratory confirmation of heparin-dependent, platelet-activating antibodies.

OBJECTIVES

To report thrombotic and major bleeding outcomes with fondaparinux in patients with a high likelihood of having acute HIT based on clinical features and a positive result in the confirmatory platelet serotonin-release assay (SRA), a sensitive and specific test for platelet-activating HIT antibodies.

METHODS/PATIENTS

We reviewed consecutive eligible patients with SRA-positive HIT (mean peak serotonin release, 91% [normal, < 20%]; mean IgG-specific PF4/heparin enzyme immunoassay result, 2.53 optical density units [normal, < 0.45 units]) in one medical center over a 30-month period who received fondaparinux for anticoagulation during acute HIT (platelet count, < 150 × 10(9) L(-1)). Where available, plasma samples were used to measure thrombin-antithrombin (TAT) complex levels.

RESULTS

Sixteen patients with SRA-positive HIT received fondaparinux: 14 surgical (11 after cardiac surgery; three after vascular surgery) and two medical (acute stroke). Fifty-six per cent of patients had HIT-associated thrombosis at the time of diagnosis. No patient developed new, recurrent or progressive thrombosis; one patient developed a major bleed (calf hematoma). One patient judged to have irreversible tissue necrosis before receiving fondaparinux therapy ultimately required limb amputation. TAT complex levels were reduced within 24 h of starting fondaparinux, and 13 of 13 patients were successfully switched to warfarin.

CONCLUSION

Fondaparinux shows promise for the treatment of patients with SRA-positive acute HIT.

A critical appraisal of bleeding events reported in venous thromboembolism prevention trials of patients undergoing hip and knee arthroplasty

BACKGROUND

Anticoagulants are effective for the prevention of venous thromboembolism (VTE) but cause bleeding. Interpretation of the risks and benefits of new anticoagulant regimens for VTE prevention is complicated by a lack of standardized definitions and reporting of bleeding. We reviewed the reporting of bleeding in randomized controlled trials of new anticoagulants compared with standard doses of enoxaparin in hip and knee arthroplasty, and examined the possible impact of differences in the definition of major bleeding on interpretation of the trial results.

METHODS

Electronic searches identified 16 phase III trials published between 2001 and 2010 involving 41,265 patients comparing one of five new anticoagulants with a common comparator, enoxaparin.

RESULTS

Major bleeding rates in patients treated with enoxaparin ranged from 0.1% to 3.1% in hip arthroplasty trials and from 0.2% to 1.4% in knee arthroplasty trials. In studies that excluded surgical-site bleeding from the definition, major bleeding rates were about 10-fold lower than in those which included surgical-site bleeding. Within the individual trials, the choice of bleeding definition and the methods of assessment of bleeding influenced the conclusions regarding the risk of bleeding with new anticoagulant regimens relative to enoxaparin. Eight of the 16 studies demonstrated a ≥ 40% relative risk differences in major bleeding between treatment groups but the difference was statistically significant in only two of these trials.

CONCLUSION

Randomized VTE prevention trials report markedly different rates of major bleeding despite similar patient populations and doses and durations of anticoagulant prophylaxis and were underpowered to detect modest differences in patient-important bleeding events. Standardization of bleeding definitions and reporting seems desirable.

Comparison of the anticoagulant intensities of fondaparinux and enoxaparin in the Organization to Assess Strategies in Acute Ischemic Syndromes (OASIS)-5 trial

BACKGROUND

In the OASIS-5 trial, fondaparinux reduced major bleeding with similar short-term efficacy as enoxaparin but lowered death and stroke during long-term follow-up. The mechanism of lower bleeding and improved efficacy with fondaparinux is uncertain.

METHODS AND RESULTS

We compared the anti-Xa concentration (reflecting drug levels), Xa clot time (reflecting anticoagulant effect) and endogenous thrombin potential (ETP; a global test of hemostatic function) in plasma samples collected 6, 24 and 72 h after the first dose of the study drug in 48 patients randomly assigned fondaparinux 2.5 mg day(-1) and 42 patients assigned enoxaparin 1 mg kg(-1) twice daily in the OASIS-5 trial. Patients assigned to fondaparinux compared with enoxaparin had a significantly lower mean anti-Xa level [0.52 IU mL(-1) (SD 0.22 IU mL(-1)) vs. 1.2 IU mL(-1) (SD 0.45 IU mL(-1)), P<0.0001] and Xa clot time [64.9 s (SD 17.7 s) vs. 111.8 s (SD 29.6 s), P<0.0001], and significantly higher ETP area under the curve (AUC) [386.7 mA (SD 51.5 mA) vs. 206.4 mA (SD 90.6 mA), P<0.001] at 6 h, and these differences remained evident at 24 and 72 h. There was significantly less variability of the results of anti-Xa levels, Xa clot time and ETP AUC for fondaparinux compared with enoxaparin at 6 h (P<0.001 for each comparison).

CONCLUSION

Fondaparinux 2.5 mg day(-1) compared with enoxaparin 1 mg kg(-1) twice daily produces less variable anticoagulant effect and lower mean anticoagulant intensity. These results most likely explain the reduced risk of bleeding seen with fondaparinux compared with enoxaparin in the OASIS-5 trial and suggest that a lower intensity of anticoagulation than used in the past may be sufficient to prevent recurrent ischemic events and death in patients with ACS who are concurrently treated with aspirin and clopidogrel.

Mean platelet volume as a predictor of cardiovascular risk: a systematic review and meta-analysis

AIM

To determine whether an association exists between mean platelet volume (MPV) and acute myocardial infarction (AMI) and other cardiovascular events. Platelet activity is a major culprit in atherothrombotic events. MPV, which is widely available in clinical practice, is a potentially useful biomarker of platelet activity in the setting of cardiovascular disease.

METHODS AND RESULTS

We performed a systematic review and meta-analysis investigating the association between MPV and AMI, all-cause mortality following myocardial infarction, and restenosis following coronary angioplasty. Results were pooled using random-effects modeling. Pooled results from 16 cross-sectional studies involving 2809 patients investigating the association of MPV and AMI indicated that MPV was significantly higher in those with AMI than those without AMI [mean difference 0.92 fL, 95% confidence interval (CI) 0.67-1.16, P < 0.001). In subgroup analyses, significant differences in MPV existed between subjects with AMI, subjects with stable coronary disease (P < 0.001), and stable controls (P < 0.001), but not vs. those with unstable angina (P = 0.24). Pooled results from three cohort studies involving 3184 patients evaluating the risk of death following AMI demonstrated that an elevated MPV increased the odds of death as compared with a normal MPV (11.5% vs. 7.1%, odds ratio 1.65, 95% CI 1.12-2.52, P = 0.012). Pooled results from five cohort studies involving 430 patients who underwent coronary angioplasty revealed that MPV was significantly higher in patients who developed restenosis than in those who did not develop restenosis (mean difference 0.98 fL, 95% CI 0.74-1.21, P < 0.001).

CONCLUSIONS

Elevated MPV is associated with AMI, mortality following myocardial infarction, and restenosis following coronary angioplasty. These data suggest that MPV is a potentially useful prognostic biomarker in patients with cardiovascular disease. Whether the relationship is causal, and whether MPV should influence practice or guide therapy, remains unknown.

Effect of a simple two-step warfarin dosing algorithm on anticoagulant control as measured by time in therapeutic range: a pilot study

BACKGROUND

The efficacy and safety of vitamin K antagonists for the prevention of thromboembolism are dependent on the time for which the International Normalized Ratio (INR) is in the therapeutic range. The objective of our study was to determine the effect of introducing a simple two-step dosing algorithm, as compared with dosing by anticoagulation clinic staffs on the basis of their experience, on time in therapeutic range (TTR) of warfarin therapy.

METHODS

We compared TTRs of all clinic patients before and after the introduction of a simple two-step dosing algorithm at a single anticoagulation clinic in Canada, between 1 August 2006 and 24 December 2008. TTR was calculated using the linear interpolation method of Rosendaal.

RESULTS

We included 873 patients in the 'before' phase and 1088 patients in the 'after' phase. Introduction of the dosing algorithm significantly increased TTR of patients with a therapeutic INR range of 2-3 from 67.2% to 73.2% (P < 0.001), and that of patients with a therapeutic INR range of 2.5-3.5 from 49.8% to 63.8% (P < 0.001).

CONCLUSIONS

The introduction of a simple two-step warfarin-dosing algorithm in place of dosing by experienced anticoagulation clinic staff significantly improved mean TTR for patients in a tertiary-care anticoagulation clinic. This inexpensive and widely applicable algorithm has the potential to improve warfarin control.

Mean platelet volume as a predictor of cardiovascular risk: a systematic review and meta-analysis

AIM

To determine whether an association exists between mean platelet volume (MPV) and acute myocardial infarction (AMI) and other cardiovascular events. Platelet activity is a major culprit in atherothrombotic events. MPV, which is widely available in clinical practice, is a potentially useful biomarker of platelet activity in the setting of cardiovascular disease.

METHODS AND RESULTS

We performed a systematic review and meta-analysis investigating the association between MPV and AMI, all-cause mortality following myocardial infarction, and restenosis following coronary angioplasty. Results were pooled using random-effects modeling. Pooled results from 16 cross-sectional studies involving 2809 patients investigating the association of MPV and AMI indicated that MPV was significantly higher in those with AMI than those without AMI [mean difference 0.92 fL, 95% confidence interval (CI) 0.67-1.16, P < 0.001). In subgroup analyses, significant differences in MPV existed between subjects with AMI, subjects with stable coronary disease (P < 0.001), and stable controls (P < 0.001), but not vs. those with unstable angina (P = 0.24). Pooled results from three cohort studies involving 3184 patients evaluating the risk of death following AMI demonstrated that an elevated MPV increased the odds of death as compared with a normal MPV (11.5% vs. 7.1%, odds ratio 1.65, 95% CI 1.12-2.52, P = 0.012). Pooled results from five cohort studies involving 430 patients who underwent coronary angioplasty revealed that MPV was significantly higher in patients who developed restenosis than in those who did not develop restenosis (mean difference 0.98 fL, 95% CI 0.74-1.21, P < 0.001).

CONCLUSIONS

Elevated MPV is associated with AMI, mortality following myocardial infarction, and restenosis following coronary angioplasty. These data suggest that MPV is a potentially useful prognostic biomarker in patients with cardiovascular disease. Whether the relationship is causal, and whether MPV should influence practice or guide therapy, remains unknown.

VITATOPS, the VITAmins TO prevent stroke trial: rationale and design of a randomised trial of B-vitamin therapy in patients with recent transient ischaemic attack or stroke (NCT00097669) (ISRCTN74743444)

BACKGROUND

Epidemiological studies suggest that raised plasma concentrations of total homocysteine (tHcy) may be a common, causal and treatable risk factor for atherothromboembolic ischaemic stroke, dementia and depression. Although tHcy can be lowered effectively with small doses of folic acid, vitamin B(12) and vitamin B(6), it is not known whether lowering tHcy, by means of B vitamin therapy, can prevent stroke and other major atherothromboembolic vascular events.

AIM

To determine whether the addition of B-vitamin supplements (folic acid 2 mg, B(6) 25 mg, B(12) 500 microg) to best medical and surgical management will reduce the combined incidence of stroke, myocardial infarction (MI) and vascular death in patients with recent stroke or transient ischaemic attack (TIA) of the brain or eye.

DESIGN

A prospective, international, multicentre, randomised, double blind, placebo-controlled clinical trial.

SETTING

One hundred and four medical centres in 20 countries on five continents.

SUBJECTS

Eight thousand (6600 recruited as of 5 January, 2006) patients with recent (<7 months) stroke (ischaemic or haemorrhagic) or TIA (brain or eye).

RANDOMISATION

Randomisation and data collection are performed by means of a central telephone service or secure internet site.

INTERVENTION

One tablet daily of either placebo or B vitamins (folic acid 2 mg, B(6) 25 mg, B(12) 500 mug).

PRIMARY OUTCOME

The composite of stroke, MI or death from any vascular cause, whichever occurs first. Outcome and serious adverse events are adjudicated blinded to treatment allocation.

SECONDARY OUTCOMES

TIA, unstable angina, revascularisation procedures, dementia, depression. STATISTICAL POWER: With 8000 patients followed up for a median of 2 years and an annual incidence of the primary outcome of 8% among patients assigned placebo, the study will have at least 80% power to detect a relative reduction of 15% in the incidence of the primary outcome among patients assigned B vitamins (to 6.8%/year), applying a two-tailed level of significance of 5%.

CONCLUSION

VITATOPS aims to recruit and follow-up 8000 patients between 1998 and 2008, and provide a reliable estimate of the safety and effectiveness of folic acid, vitamin B(12), and vitamin B(6) supplementation in reducing recurrent serious vascular events among a wide range of patients with TIA and stroke throughout the world.

Gastrointestinal bleeding after acute ischemic stroke

OBJECTIVE

Recent studies report that major bleeding is associated with a significant increase in mortality after acute coronary syndrome. Major bleeding has also been reported to be common after ischemic stroke, most often gastrointestinal, but its association with clinical outcome is less certain. We sought to describe the incidence, risk factors, and association with clinical outcomes of gastrointestinal bleeding following acute ischemic stroke.

METHODS

Consecutive patients with acute ischemic stroke, who were admitted to 11 Ontario hospitals, were identified from the Registry of the Canadian Stroke Network (2003-2006). Stroke severity was measured using the Canadian Neurological Scale. Dependence was measured with the modified Rankin Scale (mRS), and categorized into strokes with no or mild-moderate dependency (mRS 0-3) and those with severe dependence or death (mRS 4-6). Multivariable logistic regression was used to determine the association between gastrointestinal bleeding and clinical outcome (death or severe dependence at hospital discharge and 6-month mortality), independent of comorbidities and in-hospital medical complications.

RESULTS

In total, 6,853 patients with acute ischemic stroke were included. One hundred (1.5%) patients experienced gastrointestinal hemorrhage during hospitalization, of which 36 (0.5%) required blood transfusion. On multivariable analyses, previous history of peptic ulcer disease, cancer, and stroke severity were independent predictors of gastrointestinal bleeding. Gastrointestinal hemorrhage was independently associated with death or severe dependence at discharge (OR 3.3; 95% CI 1.9-5.8) and mortality at 6 months (HR 1.5; 95% CI 1.1-2.0).

CONCLUSIONS

Gastrointestinal hemorrhage is relatively uncommon after acute ischemic stroke but is associated with increased odds of death and severe dependence.

Clinical factors influencing the sensitivity to warfarin when restarted after surgery

BACKGROUND AND OBJECTIVE

Resumption of oral anticoagulation after surgery may result in a different maintenance dose of warfarin than before the procedure. Knowledge of the clinical determinants of postoperative response could help avoid excessive anticoagulation in sensitive patients or avoid extended delays in achieving a therapeutic level in resistant patients.

DESIGN

Retrospective review.

SUBJECTS

Two hundred warfarin-treated patients who were managed by our clinic for surgery.

OUTCOME

Two independent adjudicators classified the postoperative response to warfarin as Resistant, Normal or Sensitive, based on previous maintenance dose, international normalized ratio (INR) on the day of resumption, number of days until INR of >1.9 and doses of warfarin given. A third adjudicator resolved disagreements. Clinical data were extracted from the patient records and correlated with the response.

RESULTS

Interobserver agreement for classification of postoperative response was moderate (weighted kappa 0.46) with 37 (18.5%) considered resistant, 135 (67.5%) normal, 27 (13.5%) sensitive and one patient was not classifiable. The main type of surgery was cardiac. In univariable analysis only addition of amiodarone after surgery was associated with a sensitive response (P = 0.04). After adjustment for all other factors with an ordered categorical response, amiodarone remained as the sole independent risk factor (P = 0.02) for a sensitive response, odds ratio 0.41 (95% confidence interval 0.19-0.89) for Normal instead of Sensitive or for Resistant instead of Normal.

CONCLUSION

Altered sensitivity to warfarin occurs in about one-third of patients after surgery and can be predicted by the introduction of concomitant amiodarone therapy but not by patient factors or the nature of the procedure. Changes in concomitant medications after surgery should alert doctors of the potential for increased sensitivity to warfarin.

Combined antiplatelet and anticoagulant therapy: clinical benefits and risks

The combination of anticoagulant and antiplatelet therapy is more effective than antiplatelet therapy alone for the initial and long-term management of acute coronary syndromes but increases the risk of bleeding. Antiplatelet therapy is often combined with oral anticoagulants in patients with an indication for warfarin therapy (e.g. atrial fibrillation) who also have an indication for antiplatelet therapy (e.g. coronary artery disease) but the appropriateness of such an approach is unresolved. Anticoagulation appears to be as effective as antiplatelet therapy for long-term management of acute coronary syndrome and stroke, and possibly peripheral artery disease, but causes more bleeding. Therefore, in such patients who develop atrial fibrillation, switching from antiplatelet therapy to anticoagulants might be all that is required. The combination of anticoagulant and antiplatelet therapy has only been proven to provide additional benefit over anticoagulants alone in patients with prosthetic heart valves. The combination of aspirin and clopidogrel is not as effective as oral anticoagulants in patients with atrial fibrillation, whereas the combination of aspirin and clopidogrel is more effective than oral anticoagulants in patients with coronary stents. Whether the benefits of triple therapy outweigh the risks in patients with atrial fibrillation and coronary stents requires evaluation in randomized trials.

Combined antiplatelet and anticoagulant therapy: clinical benefits and risks

The combination of anticoagulant and antiplatelet therapy is more effective than antiplatelet therapy alone for the initial and long-term management of acute coronary syndromes but increases the risk of bleeding. Antiplatelet therapy is often combined with oral anticoagulants in patients with an indication for warfarin therapy (e.g. atrial fibrillation) who also have an indication for antiplatelet therapy (e.g. coronary artery disease) but the appropriateness of such an approach is unresolved. Anticoagulation appears to be as effective as antiplatelet therapy for long-term management of acute coronary syndrome and stroke, and possibly peripheral artery disease, but causes more bleeding. Therefore, in such patients who develop atrial fibrillation, switching from antiplatelet therapy to anticoagulants might be all that is required. The combination of anticoagulant and antiplatelet therapy has only been proven to provide additional benefit over anticoagulants alone in patients with prosthetic heart valves. The combination of aspirin and clopidogrel is not as effective as oral anticoagulants in patients with atrial fibrillation, whereas the combination of aspirin and clopidogrel is more effective than oral anticoagulants in patients with coronary stents. Whether the benefits of triple therapy outweigh the risks in patients with atrial fibrillation and coronary stents requires evaluation in randomized trials.

Association between asymptomatic deep vein thrombosis detected by venography and symptomatic venous thromboembolism in patients undergoing elective hip or knee surgery

BACKGROUND

Venography is commonly used to compare the efficacy of different thromboprophylaxis strategies for preventing deep vein thrombosis (DVT) in patients undergoing total hip replacement (THR) or total knee replacement (TKR).

METHODS

We explored the relation between asymptomatic DVT and symptomatic venous thromboembolism (VTE) in patients undergoing THR or TKR treated with standard doses of enoxaparin (30 mg b.i.d. or 40 mg o.d.) by comparing the incidence of asymptomatic DVT in venographic studies with the incidence of symptomatic VTE in studies where venography was not performed.

RESULTS

In 10 venographic studies involving 5796 patients, the incidence of asymptomatic DVT after THR was 13.2% [95% CI, 12.2-14.2%] and after TKR was 38.1% (95% CI, 35.5-40.8%). In two studies involving 3500 patients who did not undergo venography, the 90-day incidence of symptomatic VTE after THR was 2.7% (95% CI, 2.1-3.4%) and after TKR was 1.8% (95% CI, 0.9-2.7%). For every symptomatic VTE in THR studies where venography was not performed there were five asymptomatic DVTs in the venographic studies; for TKR, the ratio was 1:21. The incidence of asymptomatic DVT and the symptomatic VTE/asymptomatic DVT ratio was influenced by the venogram reading committee (Gothenburg vs. Hamilton: total DVT after THR, 19.5% vs. 8.7%, P < 0.0001; for TKR, 42.7% vs. 27.2%, P < 0.0001).

CONCLUSIONS

Comparisons across trials show a consistent relation between asymptomatic venographic DVT in patients undergoing elective THR or TKR surgery and symptomatic VTE in patients not undergoing venography. Differences exist in the strength of the relation depending on the type of surgery and the venogram reading committee.