Optimal duration of anticoagulant therapy after an episode of venous thromboembolism

Optimal Duration of Treatment in Surgical Patients With Calf Venous Thrombosis Involving One or More Veins

The aim of this study was to evaluate different durations of treatment in patients with calf venous thrombosis (CVT) involving 1 or more deep veins. The authors studied 2 groups of patients with postsurgical CVT diagnosed by echo-color Doppler. The first group consisted of 68 patients with CVT involving a single vein, and the second group consisted of 124 patients with CVT involving 2 or more veins. Immediately after diagnosis, all patients were treated with nadroparin calcium and sodium warfarin. Heparin treatment was withdrawn after 5–6 days of treatment, when the international normalized ratio (INR) was stabilized between 2 and 3. Each group was divided into 2 subgroups receiving anticoagulation treatment for 6 or 12 weeks, respectively. The endpoint was proximal extension of the thrombotic lesion, defined as the extension of the thrombus to the popliteal and/or femoral vein. In patients with single-vessel CVT there was no significant difference between the 2 subgroups, whereas in patients with CVT involving 2 or more vessels, a statistically significant difference was observed, the number of cases showing proximal extension of the thrombus being higher among patients treated for 6 weeks. Twelve weeks of anticoagulation treatment is better than 6 weeks only in patients with postsurgical CVT involving 2 or more veins.

Recurrent venous thromboembolism: what is the risk and how to prevent it

Venous thromboembolism (VTE) that includes deep vein thrombosis and/or pulmonary embolism is a frequent, severe, and potentially lethal disease. After a first episode, VTE has a strong tendency to recur. While VTE is an acute disease, it may have variable outcomes in early and late phases after initial presentation. Furthermore, the incidence of late, clinically important consequences (postthrombotic syndrome and/or chronic thromboembolic pulmonary hypertension) increases in case of recurrent events. The aims of the present review are (i) to analyze the incidence and risk factors for recurrence of VTE (either those related to the type of first thrombotic event or to the patients), the risks associated with occurrence of recurrent events, and the problems linked to the diagnosis, not always easy, of recurrent events; (ii) to discuss whether or not it is possible to predict the individual risk of recurrence after a first event, by stratifying patients at high or low risk of recurrence, and how this can influence their treatment; (iii) to comment what the current guidelines and guidance suggest/recommend about anticoagulant treatment after a first VTE event and, finally, to propose practical indications on how to manage individual patients affected by VTE.

Systematic review of emergency physician-performed ultrasonography for lower-extremity deep vein thrombosis

OBJECTIVES

The authors performed a systematic review to evaluate published literature on diagnostic performance of emergency physician-performed ultrasonography (EPPU) for the diagnosis and exclusion of deep venous thrombosis (DVT).

METHODS

Structured search criteria were used to query MEDLINE and EMBASE, followed by a hand search of published bibliographies. Relevance and inclusion criteria required prospective investigation of emergency department (ED) outpatients with suspected DVT; diagnostic evaluations had to consist of EPPU followed by criterion standard (radiology-performed) imaging. Two authors independently extracted data from included studies; study quality was assessed utilizing a validated tool for quality assessment of diagnostic accuracy studies (QUADAS). Pooled data were analyzed using an unweighted summary receiver-operating-characteristic (SROC) curve; sensitivity and specificity were estimated using a random effects model.

RESULTS

The initial search yielded 1,162 publications. Relevance screening and selection yielded six articles including 936 patients. Four of the six studies reported adequate blinding but a number of other methodologic flaws were identified. A random effects model yielded an overall sensitivity of 0.95 (95% confidence interval [CI] = 0.87 to 0.99) and specificity of 0.96 (95% CI = 0.87 to 0.99).

CONCLUSIONS

Systematic review of six studies suggests that EPPU may be accurate for the diagnosis of DVT compared with radiology-performed ultrasound (US). However, given the methodologic limitations identified among the primary studies, the estimates of diagnostic test performance may be overly optimistic. Further research into EPPU for suspected DVT is needed before it can be adopted into routine clinical practice.

Duration of vitamin K antagonist therapy for venous thromboembolism: a systematic review of the literature

PURPOSE

The aim of this study was to evaluate the evidence on the optimal duration of vitamin K antagonist (VKA) therapy for venous thromboembolism (VTE).

METHODS

Randomized controlled trials of VKA for VTE were identified by a computerized database search. Summary event rates for relevant outcomes were calculated using a random effects model with 95% confidence intervals (95% CI).

RESULTS

Ten studies met inclusion criteria. The incidence of recurrent VTE (3 months, 7.9 VTE per 100 patient-years [95% CI, 5.2 to 10] versus 4-12 months, 4.9 VTE per 100 patient-years [95% CI, 3.6 to 6.2] versus continuous therapy, 0.7 VTE per 100 patient-years [95% CI, 0.3 to 1.1]) and total adverse events (3 months, 11.2 events per 100 patient-years [95%CI, 7.1 to 15.4] versus 4-12 months, 7.4 events per 100 patient-years [95%CI, 6.2 to 8.5] versus continuous therapy 3.1 events per 100 patient-years [95%CI, 2.2 to 4.0] declined as VKA therapy duration increased. Continuous reduced intensity therapy (INR 1.5-2) was associated with more recurrent VTE (2.3 VTE per 100 patient-years [95%CI, 1.5 to 3.0]). Continuous VKA therapy (INR 2-3) was beneficial for patients with a second VTE and antiphospholipid antibodies. The incidence of recurrent VTE was similar with 6 or 12 weeks of therapy for isolated calf DVT.

CONCLUSION

Randomized controlled trials indicate that continuous VKA therapy (INR 2-3) for VTE is associated with better clinical outcomes than shorter durations. Patients with a second VTE or antiphospholipid antibodies also benefit from continuous anticoagulation. Patients with calf DVT should be treated for at least 6 weeks.

Traitement de la maladie thromboembolique veineuse chez les patients souffrant de cancers

PURPOSE

Venous tromboembolic treatment in patients with cancer can be a clinical dilemma. Comorbid conditions, significant risk of recurrence of bleeding associated with warfarin, difficult venous access, are some of the factors that often complicate anticoagulants therapy in patients with cancer.

EXEGESIS

Low molecular weight heparin has replaced unfractionated heparin as the first line treatment in the majority of patients with venous thromboembolism and cancer, in hospital or safely at home. Recent trial demonstrated that long-term low molecular weight heparin administrated over a 6-month period reduced the rate of recurrence venous thromboembolism with non increase in bleeding compared with oral anticoagulant therapy. Placement of an inferior vena caval filter should be reserved for patients with active or very high risk of bleeding, but oncologist should consider these sobering results in such patients. Whether anticoagulants might also improve cancer survival rates independent of their effect on thromboembolism deserves further investigation.

PERSPECTIVE

In future, new antithrombotic agents such as oral direct thrombin or long-acting synthetic factor Xa inhibitor may be useful in these patients.

Haemophilia and thrombophilia: an unexpected association!

In patients with haemophilia, a close correlation is usually observed between the clinical expression of the disease and plasmatic factor VIII/factor IX clotting activity. However, some patients experience milder bleeding phenotypes than others, although they exhibit a similar biological profile. The high prevalence of some inherited thrombophilia risk factors offers the possibility of a co-inheritance in haemophilic patients which could influence the phenotypic expression of the disease. Rare thrombotic complications occurring in haemophiliacs could also be facilitated by the co-inheritance of modifier genes. The majority of thrombotic events occurring in haemophiliacs are in relation to clotting factor infusions or central venous catheters. Concerning surgical situations, in the absence of therapeutic recommendations, postoperative thromboprophylaxis is not systematically performed in haemophiliacs. However, substitutive treatment more or less completely corrects the coagulation defect and makes the venous thrombosis risk closer to the control population. It should be emphasized that haemophilia does not fully protect against venous thromboembolic disease. Patients with haemophilia very infrequently experience thrombotic events. Thus, the management of thrombotic complications occurring in haemophilic patients should be discussed in each case according to the precipitating risk factors, the clinical context and the thrombo-haemorrhagic balance of the patient with respect to a particular clinical situation.

Should patients on warfarin for 3 months for idiopathic proximal deep venous thrombosis receive bridging therapy precolonoscopy (with expected biopsy)?

A 63-year-old woman presents to discuss periprocedure anticoagulation management. She has been on oral warfarin with an international normalized ratio between 2 and 3 for the past 3 months because of an idiopathic left popliteal vein thrombosis. A colonic polyp was identified during her purely diagnostic colonoscopy performed as part of her age- and gender-appropriate cancer screening. Immediate repeat colonoscopy with polypectomy is recommended. The clinician is asked to provide periprocedural anticoagulation recommendations.

Diagnosis, investigation, and management of deep vein thrombosis

Deep vein thrombosis is an important cause of morbidity and mortality worldwide, and its clinical diagnosis is unreliable. This article explains current screening and diagnostic methods as well as treatment

Blood rheology in deep venous thrombosis--relation to persistent and transient risk factors

INTRODUCTION

The risk of recurrence in patients with symptomatic deep venous thrombosis (DVT) is higher in patients with persistent risk factors than in patients with transient risk factors. The purpose of this prospective study was to investigate the course of rheological variables in patients with DVT up to 1 year after the acute event in relation to risk factors.

PATIENTS AND METHODS

In 37 patients with proven DVT plasma fibrinogen, plasma viscosity, red cell aggregation, whole blood viscosity, hematocrit and platelet aggregation were studied in the acute phase, at 6 weeks and at 12 months.

RESULTS

In the acute phase, patients had higher fibrinogen (medians and ranges; 450 [270-611] vs. 247 [170-340] mg/dl, p < 0.01), plasma viscosity (1.67 [1.48-1.96] vs. 1.60 [1.50-1.70] mPa s, p < 0.01), red cell aggregation (9.76 [5.87-12.66] vs. 5.66 [3.67-8.46] arbitrary units; p < 0.01) and whole blood viscosity (5.78 [5.61-5.87] vs. 5.59 [5.27-5.9] mPa s, p < 0.01), but lower hematocrit (40 [32-46] vs. 45 [38-50]%, p < 0.01) and platelet aggregation (by epinephrine: 41 [13-85] vs. 79 [29-91]%, (p < 0.01) than controls. During the 1-year follow-up, fibrinogen, plasma viscosity, red cell aggregation and whole blood viscosity constantly decreased, whereas hematocrit and platelet aggregation increased in the total of patients (all p < 0.01). Subgroup analysis according to risk factors showed that at 12 months patients with persistent risk factors (N = 21) had higher plasma fibrinogen (357 [235-450] vs. 247 [214-335] mg/dl, p < 0.01), plasma viscosity (1.65 [1.50-1.80] vs. 1.59 [1.42-1.77] mPa s, p < 0.05) and red cell aggregation (7.82 [6.0-11.3] vs. 6.3 [5.2-7.1] arb. units, p < 0.01) than patients with transient risk factors (N = 16). Compared with controls, these variables were increased in patients with persistent risk factors (all p < 0.01), but not in patients with transient risk factors (all n.s.).

CONCLUSION

In patients with persistent risk factors rheological changes are still present 1 year after acute DVT, whereas in patients with transient risk factors blood rheology returns to normal. Further studies are needed to clarify whether blood rheology might be helpful to identify patients at high risk of recurrence.

[Duration of oral anticoagulant therapy in deep venous thrombosis of the lower limbs]

The optimal duration of oral anticoagulant therapy is a matter of debate. It is essential to balance the desired effect of the anticoagulants in reducing recurrences against the risk of major bleeding. Recent data suggest that it is necessary to tailor the duration of anticoagulation individually according to the topography of deep vein thrombosis (DVT) and the presence of risk factors. A six-week treatment for patients with isolated calf DVT is sufficient. For proximal DVT and/or pulmonary embolism, a short anticoagulant course seems sufficient in patients with temporary risk factors (three months) and a longer anticoagulant course (six months at least) is recommended for cases with permanent risk factors or idiopathic DVT. The inherited or acquired hypercoagulable states can be divides into those that are common and associated with a modest risk of recurrence (i.e. isolated factor V Leiden or G20210A prothrombin gene) and those are uncommon but associated with a high risk of recurrence (i.e. antithrombin, protein C or S deficiencies and anticardiolipin antibodies). Thus, the presence of one of these last abnormalities favours more prolonged anticoagulant therapy. For the high-risk of recurrence patients, there is a paucity of evidence based medicine particularly for patients with biological thrombophilia, and randomised controlled trials in this population are required. An assessment of low- or fixed-dose oral anticoagulation is also necessary in order to reduce the bleeding risk.

[Duration of oral anticoagulant therapy in venous thromboembolism]

PURPOSE

The optimal duration of oral anticoagulant therapy after a first episode of venous thromboembolism is still a matter of debate. It is essential to balance the desired effect of the anticoagulants in reducing recurrences against the risk of major bleeding. The aims of this paper are to describe the current concepts in this field.

CURRENT KNOWLEDGE AND KEY POINTS

Recent data, based on randomised controlled trials, suggest that it is necessary to tailor the duration of anticoagulation individually according to the topography of venous thromboembolism and the presence of risk factors. A 6-week treatment for patients with isolated calf vein thrombosis is sufficient. For proximal thrombosis and/or pulmonary embolism, a short anticoagulant course seems sufficient in patients with temporary risk factors (3 months) and a longer anticoagulant course (6 months at least) is recommended for cases with permanent risk factors or idiopathic venous thromboembolism. The inherited or acquired hypercoagulable states can be divided into those that are common and associated with a modest risk of recurrence (i.e., isolated factor V Leiden or G20210A prothrombin gene) and those that are uncommon but associated with a high risk of recurrence (i.e., antithrombin, protein C or S deficiencies and anticardiolipin antibodies). Thus, the presence of one of these last abnormalities favours more prolonged anticoagulant therapy.

FUTURE PROSPECTS AND PROJECTS

1) For patients at high risk of recurrence, there is a paucity of evidence-based medicine, particularly for patients with biological thrombophilia, and randomised controlled trials in this population are required. An assessment of low- or fixed-dose oral anticoagulation is also necessary in order to reduce the bleeding risk. 2) It is not always possible to precisely determine the optimal duration with the available data. We have performed a meta-analysis on summary data which suggests that a long course of oral anticoagulant therapy is superior to a short course. An individual meta-analytic approach is needed to draw more precise conclusions on an interesting and important clinical topic and we propose to perform this analysis in a international collaborative group.