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National Clinical Guideline Centre – Acute and Chronic Conditions (UK). Venous Thromboembolism: Reducing the Risk of Venous Thromboembolism (Deep Vein Thrombosis and Pulmonary Embolism) in Patients Admitted to Hospital. London: Royal College of Physicians (UK); 2010. (NICE Clinical Guidelines, No. 92.)

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Venous Thromboembolism: Reducing the Risk of Venous Thromboembolism (Deep Vein Thrombosis and Pulmonary Embolism) in Patients Admitted to Hospital.

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25Acute coronary syndromes

25.1. Introduction

All patients admitted with acute coronary syndrome (ACS) consisting of a history of chest pain, and raised cardiac enzymes or altered electrocardiogram should have a VTE assessment performed on admission (section 5.9). The risk of DVT in patients with ACS is estimated from the nil prophylaxis arms of trials to be 21% (95% confidence intervals 17% to 25%).

Patients diagnosed with ACS are treated with anti-thrombotics. These treatments primarily consist of aspirin, clopidogrel and heparin. The duration of each therapy varies, with aspirin often being life-long, clopidogrel in the order of 12 months and heparin for a period of three to five days post event. Patients who receive full dose anticoagulation with either intravenous unfractionated heparin (UFH) or low molecular weight heparin (LMWH) do not require further VTE prophylaxis whilst receiving full anticoagulation. Once full dose anti-coagulation is stopped the protection it provides diminishes allowing an increased risk of VTE. A repeat VTE risk assessment is required. VTE prophylaxis should be given if the assessment indicates unless the patient has significant bleeding risk.

For patients who are admitted and do not require treatment with full-dose anticoagulation, a VTE assessment is required. Studies indicate that neither aspirin nor clopidogrel when given alone provides adequate VTE protection and patients remain at risk of VTE. Patients should receive additional pharmacological prophylaxis unless the patient has a significant bleeding risk.

None of the studies identified in this chapter investigated the anti-thrombotic effect of clopidogrel and aspirin combinations. Several studies investigate the long term use of clopidogrel (which was not within the scope of this guideline) and have concluded that these combinations were relatively ineffective at reducing venous thromboembolic endpoints 61,95,118.

25.2. Evidence of methods of prophylaxis

25.2.1. Summary of comparisons identified for any outcome

Seven RCTs were identified which investigated VTE prophylaxis in patients with acute coronary syndrome 42,70,209,251,338,522,672. Most of the evidence was conducted in patients after myocardial infarction.

All included RCTs were either individually critically appraised to be of a high quality (level 1+ or level 1++) or came from systematic reviews of RCTs which had been critically appraised to be of a high quality (level 1+ or level 1++).

Figure 25-55. Number of studies which compared various types of prophylaxis methods.

Figure 25-55Number of studies which compared various types of prophylaxis methods

Numbers in boxes indicate the number of RCTs for each comparison. Boxes shaded grey indicates areas where no studies were identified.

GCS – anti-embolism/graduated compression stockings; IPCD/FID – intermittent pneumatic compression devices or foot impulse devices; LMWH – low molecular weight heparin; UFH – unfractionated heparin; Asp (HD) – high dose aspirin (>300mg), Asp (LD) - low dose aspirin (≤ 300mg); mech – mechanical prophylaxis (i.e. anti-embolism/graduated compression stockings, intermittent pneumatic compression devices or foot impulse devices); pharm – pharmacological prophylaxis

25.2.3. Additional information

25.2.3.1. All cause mortality

Only two studies reported all cause mortality as an outcome 70,672.

Table

25.2.3.2. Other outcomes

No studies reported heparin induced thrombocytopenia, post-thrombotic syndrome or chronic thromboembolic pulmonary hypertension as outcomes.

25.3. Network meta-analysis results

No network meta-analysis was completed for this population.

25.4. Cost-effectiveness evidence

We did not prioritise this population for original cost-effectiveness analysis and no relevant cost-effectiveness studies were found in the literature.

25.5. Patient views

No patient view papers were found for this population. Section 6.6 contains more information on patient views about specific prophylaxis agents.

25.6. Summary of evidence

Table 25-133Summary of evidence from direct evidence for DVT, symptomatic pulmonary embolism and major bleeding outcomes

Intervention(s)Comparison(s)Intervention favoured
DVTPEMB
Prophylaxis vs no prophylaxis
Aspirin (high dose)no prophylaxisNot SigNot SigNot Sig
UFHno prophylaxisUFHNot Sig-
Double prophylaxis vs single
Asp (LD) + GCSAsp (LD)Asp (LD) + GCS--
Cost Effectiveness
There is no relevant cost-effectiveness evidence specifically for this group.

The prophylaxis strategy which is significantly more effective in reducing DVT or PE; or resulting in significantly less major bleeding is stated in bold.

Not sig - not statistically significant difference; ‘-’ = not reported; no events – nobody in the study had the outcome. MB = Major bleeding

25.7. Recommendations and link to evidence

RecommendationDo not offer additional pharmacological or mechanical prophylaxis for VTE to patients who are having full anticoagulant therapy (for example, fondaparinux sodium, LMWH or UFH).
Relative values of different outcomesThe outcomes identified as important by the Guideline Development Group were thromboembolic events (asymptomatic and symptomatic DVT, symptomatic pulmonary embolism and fatal pulmonary embolism), bleeding events (major bleeding, fatal bleeding and stroke) and other long term events occurring as a result of VTE (chronic thromboembolic pulmonary hypertension and post thrombotic syndrome).
Trade off between clinical benefit and harmsThe risk of developing venous thromboembolism was weighed against the increased risk in bleeding caused by pharmacological prophylaxis.
Economic considerationsThere is no relevant cost-effectiveness evidence specifically for this group. However, we have built an economic model for the general medical patients and we believe that the baseline risk of VTE in the acute coronary syndrome subgroup will at least be similar to that in the general medical group. The result of the model suggests that LMWH and UFH are cost-effective strategies in general medical patients, with the former being more cost-effective than the latter. For patients with acute coronary syndromes there are further benefits from anti- coagulants in addition to their usual thromboprophylactic properties and therefore these drugs are likely to be even more cost-effective than for other population subgroups.
Quality of evidenceAll included RCTs were either individually critically appraised to be of a high quality (level 1+ or level 1++) or came from systematic reviews of RCTs which had been critically appraised to be of a high quality (level 1+ or level 1++).
The quality of evidence for this section is low. All of the studies included within this section were conducted over 15 years ago. The Guideline Development Group noted that since this time, the treatment of ACS conditions had changed and there were concerns that the included studies did not reflect the current situation.
Additionally the population of patients included in this study may not be representative of all those patients with acute coronary syndromes. Most of the studies were conducted after myocardial infarction.
Other considerationsThe current treatment for acute coronary syndrome usually involves anticoagulant treatment. In this situation where anticoagulants are provided for treatment, no additional prophylaxis is required for reducing the risk of VTE.
RecommendationConsider offering additional mechanical or pharmacological VTE prophylaxis to patients who are having antiplatelet agents to treat other conditions and who are assessed to be at increased risk of VTE (see section 5.9). Take into account the risk of bleeding (see Box 2) and of comorbidities such as arterial thrombosis.
  • If the risk of VTE outweighs the risk of bleeding, consider offering pharmacological VTE prophylaxis according to the reason for admission
  • If the risk of bleeding outweighs the risk of VTE, offer mechanical VTE prophylaxis
Recommendation–from section 5.9Regard medical patients as being at increased risk of VTE if they:
  • have had or are expected to have significantly reduced mobility for 3 days or more, or
  • are expected to have ongoing reduced mobility relative to their normal state and have one or more of the risk factors shown in Box 1.
Box 1 –Risk Factors for VTE
  • Active cancer or cancer treatment
  • Age over 60 years
  • Critical care admission
  • Dehydration
  • Known thrombophilias
  • Obesity (BMI over 30 kg/m2)
  • One or more significant medical comorbidities (for example: heart disease; metabolic, endocrine or respiratory pathologies; acute infectious diseases; inflammatory conditions)
  • Personal history or first-degree relative with a history of VTE
  • Use of hormone replacement therapy
  • Use of oestrogen-containing contraceptive therapy
  • Varicose veins with phlebitis
For women who are pregnant or have given birth within the previous 6 weeks see Chapter 30 (Pregnancy and up to 6 weeks post partum)
Recommendation–from section 5.9Assess all patients for risk of bleeding before offering pharmacological VTE prophylaxis*. Do not offer pharmacological VTE prophylaxis to patients with any of the risk factors for bleeding shown in Box 2, unless the risk of VTE outweighs the risk of bleeding.
*Consult the summary of product characteristics for the pharmacological VTE prophylaxis being used or planned for further details.
Box 2-Bleeding Risk Factors
  • Active bleeding
  • Acquired bleeding disorders (such as acute liver failure)
  • Concurrent use of anticoagulants known to increase the risk of bleeding (such as warfarin with INR higher than 2)
  • Lumbar puncture/epidural/spinal anaesthesia expected within the next 12 hours
  • Lumbar puncture/epidural/spinal anaesthesia within the previous 4 hours
  • Acute stroke
  • Thrombocytopenia (platelets less than 75 × 109/l)
  • Uncontrolled systolic hypertension (230/120 mmHg or higher)
  • Untreated inherited bleeding disorders (such as haemophilia and von Willebrand’s disease)
Trade off between clinical benefit and harmsThe outcomes identified as important by the Guideline Development Group were thromboembolic events (asymptomatic and symptomatic DVT, symptomatic pulmonary embolism and fatal pulmonary embolism), bleeding events (major bleeding, fatal bleeding and stroke) and other long term events occurring as a result of VTE (chronic thromboembolic pulmonary hypertension and post thrombotic syndrome).
Patients who are using anticoagulants and/or antiplatelets for treatment of their condition may still be at risk of VTE. The risks associated with DVT need to be traded against the risk of bleeding. In addition, some antiplatelet treatment is provided to reduce the risk of arterial side thrombosis. The risks associated with stopping these treatments should be carefully considered.
Economic considerationsNo cost effectiveness model was completed for this population. The health gain and cost savings of preventing VTE events should be balanced against the morbidity and costs associated with providing pharmacological prophylaxis including treatment of prophylaxis related adverse events such as major bleeding.
Other considerationsThe decisions about whether to add additional pharmacological prophylaxis should be based on a risk assessment of the individual patient taking into account their risk of patients. Such decisions should be made by healthcare professionals and should be documented in the patient’s notes.

25.7.1. Other recommendations of relevance

The specific recommendations for patients with acute coronary syndromes in this chapter should be read in conjunction with other relevant recommendations presented elsewhere in the guideline. These are:

25.8. Summary of recommendations

  • Do not offer additional pharmacological or mechanical prophylaxis for VTE to patients who are having full anticoagulant therapy (for example, fondaparinux sodium, LMWH or UFH).
  • Consider offering additional mechanical or pharmacological VTE prophylaxis to patients who are having antiplatelet agents to treat other conditions and who are assessed to be at increased risk of VTE (see section 5.9). Take into account the risk of bleeding (see Box 2) and of comorbidities such as arterial thrombosis.
    • If the risk of VTE outweighs the risk of bleeding, consider offering pharmacological VTE prophylaxis according to the reason for admission
    • If the risk of bleeding outweighs the risk of VTE, offer mechanical VTE prophylaxis.
  • Regard medical patients as being at increased risk of VTE if they:
    • have had or are expected to have significantly reduced mobility for 3 days or more or
    • are expected to have ongoing reduced mobility relative to their normal state and have one or more of the risk factors in Box 1.
Box Icon

Box 2

Risk factors for bleeding. Active bleeding Acquired bleeding disorders (such as acute liver failure)

Box Icon

Box 1

Risk factors for VTE. Active cancer or cancer treatment Age over 60 years

Copyright © 2010, National Clinical Guideline Centre - Acute and Chronic Conditions.

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