Incidence of arterial embolism in patients on treatment with old and new anticoagulants for venous thromboembolism.

The separate nature of venous and arterial thrombotic disorders has recently been challenged. Patients with venous thromboembolism (VTE) have an increased risk of subsequent symptomatic arterial cardiovascular events, the risk being higher in those with unexplained episodes. Among the implications of this association, there is the potential for old and new antithrombotic drugs to impact on the development of both venous and arterial cardiovascular events. According to the results of recent studies, aspirin in low doses, when administered for the long-term management of patients with unprovoked VTE, reduces by approximately 35% the risk of recurrent VTE while offering a considerable protection against the development of arterial cardiovascular events. By contrast, there is no room to expect a reduction in the risk of subsequent arterial cardiovascular events in patients treated with vitamin K antagonists (VKA) in comparison to patients in whom VKAs are discontinued. According to the results from recent randomized clinical trials, the likelihood of arterial cardiovascular events in patients on the novel direct factor Xa inhibitors is unlikely to differ from that of patients receiving conventional anticoagulation. As dabigatran has been associated with a slight increase in the risk of myocardial infarction over warfarin, its use should be discouraged in patients with coronary heart disease. The long-term use of low-dose apixaban beyond the first months in patients with unprovoked VTE may decrease the long-term risk of arterial, as well as venous, thrombotic events.

Venous thromboembolism and arterial complications.

An increasing body of evidence suggests the likelihood of a link between venous and arterial thrombosis. The two vascular complications share several risk factors, such as age, obesity, smoking, diabetes mellitus, blood hypertension, hypertriglyceridemia, and metabolic syndrome. Moreover, there are many examples of conditions accounting for both venous and arterial thrombosis, such as the antiphospholipid antibody syndrome, hyperhomocysteinemia, malignancies, infections, and the use of hormonal treatment. Finally, several recent studies have consistently shown that patients with venous thromboembolism are at a higher risk of arterial thrombotic complications than matched control individuals. We, therefore, speculate the two vascular complications are simultaneously triggered by biological stimuli responsible for activating coagulation and inflammatory pathways in both the arterial and the venous system. Future studies are needed to clarify the nature of this association, to assess its extent, and to evaluate its implications for clinical practice.

Optimal duration of anticoagulation in patients with venous thromboembolism.

The risk of recurrent venous thromboembolism (VTE) approaches 40 per cent of all patients after 10 yr of follow up. This risk is higher in patients with permanent risk factors of thrombosis such as active cancer, prolonged immobilization from medical diseases, and antiphospholipid syndrome; in carriers of several thrombophilic abnormalities, including deficiencies of natural anticoagulants; and in patients with unprovoked presentation. Patients with permanent risk factors of thrombosis should receive indefinite anticoagulation, consisting of subtherapeutic doses of low molecular weight heparin in cancer patients, and oral anticoagulants in all other conditions. Patients whose VTE is triggered by major surgery or trauma should be offered three months of anticoagulation. Patients with unprovoked VTE, including carriers of thrombophilia, and those whose thrombotic event is associated with minor risk factors (such as hormonal treatment, minor injuries, long travel) should receive at least three months of anticoagulation. The decision as to go on or discontinue anticoagulation after this period should be individually tailored and balanced against the haemorrhagic risk. Post-baseline variables, such as the D-dimer determination and the ultrasound assessment of residual thrombosis can help identify those patients in whom anticoagulation can be safely discontinued. As a few emerging anti-Xa and anti-IIa compounds seem to induce fewer haemorrhagic complications than conventional anticoagulation, while preserving at least the same effectiveness, these have the potential to open new scenarios for decisions regarding the duration of anticoagulation in patients with VTE.

Heart disease in patients with pulmonary embolism.

PURPOSE OF REVIEW: Several heart diseases are promoters of left-side cardiac thrombosis and could lead to arterial embolism. The same mechanism may be responsible for right-side cardiac thrombosis and therefore be a direct source of pulmonary embolism. RECENT FINDINGS: Yasuoka et al. showed a higher incidence of perfusion defects in lung scan in patients with spontaneous echocontrast in the right atrium than in those without it (40% and 7% respectively; P=0.006). We recently assessed the prevalence of heart diseases in 11.236 consecutive patients older than 60 years discharged from Venetian hospitals with a diagnosis of pulmonary embolism. We observed a higher prevalence of all-cause heart diseases (odds ratio 1.26; 95% confidence interval, 1.13-1.40) in patients with a diagnosis of pulmonary embolism alone (secondary or unprovoked) compared with those discharged with a diagnosis of pulmonary embolism associated with deep vein thrombosis, generating the hypothesis that some specific heart diseases in older patients could themselves be a possible source of pulmonary emboli. SUMMARY: Further prospective studies are required to confirm these findings, which have the potential to open new horizons for the interpretation and management of venous thromboembolic disease.

Heparin-induced thrombocytopenia (HIT): clinical and economic outcomes.

Heparin-induced thrombocytopenia (HIT) is an immune-mediated adverse drug reaction that occurs following exposure to unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH). HIT with thrombosis (HITT) can cause devastating venous thromboembolism or arterial clots, prolonged hospitalization, and increased costs. To explore the economic and clinical implications of HIT and HITT, we initiated a single-center patient registry. In this report, we describe patient characteristics, comorbidities, management strategies, clinical outcomes, and costs. We enrolled 349 hospitalized patients with an enzyme immunoassay-confirmed diagnosis of HIT over a 40-month period. Patients were assessed for the primary outcome of 30-day mortality, as well as baseline characteristics, development of thrombosis, and the economic impact of HIT. The primary outcome measure was 30-day mortality and occurred in 58 (16.6%) patients, 40 (15.3%) in the HIT group versus 18 (20.7%) in the HITT group (p = 0.25). The frequency of HIT was greater in patients exposed to UFH than in patients exposed to LMWH (0.8% vs. 0.2%, respectively, p < 0.001). Both HIT and HITT patients who were exposed to UFH had higher hospital costs than those exposed to LMWH ($113,100 vs. $56,352, respectively, p < 0.001). HIT remains an important clinical problem with a high mortality rate and significant cost, regardless of development of thrombosis. Prospective controlled trials need to be conducted to determine the optimal strategy to reduce the frequency of HIT.

Optimal duration of anticoagulation. Provoked versus unprovoked VTE and role of adjunctive thrombophilia and imaging tests.

Once anticoagulation is stopped, the risk of recurrent venous thromboembolism (VTE) over years after a first episode is consistently around 30%. This risk is higher in patients with unprovoked than in those with (transient) provoked VTE, and among the latter in patients with medical than in those with surgical risk factors. Baseline parameters that have been found to be related to the risk of recurrent VTE are the proximal location of deep-vein thrombosis, obesity, old age, male sex and non-0 blood group, whereas the role of inherited thrombophilia is controversial. The persistence of residual vein thrombosis at ultrasound assessment has consistently been shown to increase the risk, as do persistently high values of D-dimer and the early development of the post-thrombotic syndrome. Although the latest international guidelines suggest indefinite anticoagulation for most patients with the first episode of unprovoked VTE, strategies that incorporate the assessment of residual vein thrombosis and D-dimer have the potential to identify subjects in whom anticoagulation can be safely discontinued. Moreover, new opportunities are offered by a few emerging anti-Xa and anti-IIa oral compounds, which are likely to induce fewer haemorrhagic complications than vitamin K antagonists while preserving the same effectiveness; and by low-dose aspirin, which has the potential to prevent the occurrence of both venous and arterial thrombotic events.

Fondaparinux in the initial and long-term treatment of venous thromboembolism.

BACKGROUND: Even in the absence of evidence on its long-term efficacy and safety, a number of patients with venous thromboembolism (VTE) receive long-term therapy with fondaparinux alone in everyday practice. METHODS: We used the Registro Informatizado de Enfermedad Tromboembólica (RIETE) registry to compare the rate of VTE recurrences and major bleeding at 10 and 90 days in patients with and without cancer. For long-term therapy, fondaparinux was compared with vitamin K antagonists (VKA) in patients without cancer and with low-molecular-weight heparin (LMWH) in those with cancer. RESULTS: Of 47,378 patients recruited, 46,513 were initially treated with heparin, 865 with fondaparinux. Then, 263 patients (78 with cancer) were treated for at least 3 months with fondaparinux. After propensity-score matching, there were no differences between patients receiving initial therapy with heparin or fondaparinux. Among patients with cancer, there were no differences between fondaparinux and LMWH. Among patients without cancer, the long-term use of fondaparinux was associated with an increased risk of major bleeding (3.24 % vs. 0.95 %, p<0.05). CONCLUSIONS: An unexpected high rate of major bleeding was observed in non-cancer patients treated with long-term fondaparinux. Our small sample does not allow to derive relevant conclusions on the use of fondaparinux in cancer patients.

What are the pharmacotherapy options for treating venous thromboembolism in cancer patients?

INTRODUCTION: Venous thromboembolism (VTE) is a frequent complication in patients with malignancies. The treatment of VTE disorders in cancer patients remains a difficult clinical task. AREAS COVERED: Current evidence on the most appropriate initial and long-term treatment of cancer patients with VTE was addressed, as was the management of recurrent VTE despite anticoagulation, the management of incidentally detected isolated pulmonary embolism (PE), the potential role of the novel direct oral anticoagulants and the impact of low-molecular-weight heparin (LMWH) on cancer evolution. EXPERT OPINION: LMWHs are the cornerstone of VTE treatment in cancer patients. The intensity and duration of treatment are dependent on several factors that need to be individually evaluated. The novel oral anticoagulants should be investigated more carefully before being routinely implemented in the treatment of cancer-associated VTE. Incidentally detected isolated sub-segmental PE is unlikely to require systematic full-dose anticoagulation. Evidence favoring an impact of LMWH on survival in cancer patients is weak.

Comparison of four scores to predict major bleeding in patients receiving anticoagulation for venous thromboembolism: findings from the RIETE registry.

Stratification of the individual bleeding risk prior to initiation of anticoagulation in patients with acute venous thromboembolism (VTE) has the potential to assist clinicians in making decisions about the proper intensity and duration of antithrombotic therapy. It is unclear which of the validated and internationally accepted scores recommended for the achievement of this important task has the best predictive value. We compared the predictive value of four validated scores (by Landefeld, Beyth, Kuijer and Ruiz-Gimenez, respectively) for the development of major bleeding complications occurring in the first 3 months in patients with acute VTE treated with conventional anticoagulation. Based on the population of RIETE Registry (international registry of patients with acute VTE), we identified those patients presenting all the required prognostic variables, and then calculated the ability of each score for predicting the bleeding risk. Of 40,265 eligible patients, we identified 8,717 meeting the recruitment criteria. Overall, 0.9 % of patients experienced at least one episode of major bleeding within 90 days of the index event. The proportion of patients classified as having a low risk varied between 1.2 and 3.7 %, that of patients having an intermediate risk between 76 and 93 %, and that of patients classified as having a high risk between 6.1 and 18 %. The area under the receiver operating characteristic ranged between 0.55 and 0.60, the positive predictive value between 1.5 and 3.2, and the likelihood ratio between 0.72 and 1.59. In conclusion, all four scores show a very low ability to predict the bleeding risk in patients with acute VTE undergoing conventional anticoagulation.