European guidelines for acute pulmonary embolism

Sep 2 2008

Acute pulmonary embolism (PE) is a relatively common cardiovascular emergency. Clots originating in the leg veins may become detached and obstruct the lung vessels. This obstruction may lead to a rise of pressure in the pulmonary circulation and possibly to life-threatening heart failure.

PE is a difficult diagnosis that may be missed because of non-specific complaints. On the other hand, early diagnosis is fundamental since immediate treatment is highly effective. Depending on how critical the patient's condition is on admission, initial therapy is primarily aimed either at life-saving restoration of blood flow through the occluded pulmonary arteries or at prevention of potentially deadly recurrences (new episodes) of PE.

The first edition of the ESC Clinical Practice Guidelines on PE was published in 2000. The 2008 update focuses on:

1. currently available and validated methods of diagnosis
2. prognostic evaluation (prediction of outcome and death risk)
3. therapy of PE; and
4. management in specific situations such as pregnancy

In contrast to previous guidelines, we decided to grade the body of evidence supporting both treatment and diagnosticprocedures, because the latter are of particular importance in the management of PE.

For diagnostic tests, the most robust data come from large-scale accuracy or outcome studies. Accuracy studies are designed to establish the value of a diagnostic test (sensitivity and specificity) by comparing test results to a so-called gold standard. Outcome studies evaluate patient outcomes when a given diagnostic test or strategy is used for clinical decision-making. Apart from individual diagnostic tests, the present guidelines review and propose specific diagnostic algorithms, that is combinations of tests which permit the confirmation or exclusion of PE in clinical practice using a step-by-step approach. A further section of the guidelines is devoted to prognostic assessment of PE by reviewing and grading the clinical, ultrasound and laboratory findings which allow us to estimate the death and complication risk during the early, in-hospital phase of the disease. This assessment and the classification of PE into high-risk, low-risk and intermediate-risk is particularly useful for guiding treatment strategies which are reviewed in the next section of the guideline.

Thus, in high-risk PE, immediate use of thrombolytic drugs (clot busters) or the surgical removal or catheter suction of the clots from the lung vessels is mandatory in order to save the patient's life. In low-risk PE, however, treatment is less aggressive and focusses on the prevention of future PE episodes. This goal is achieved by the use of so-called anticoagulants (blood thinners), including daily injections of low molecular weight heparin for the first few days, followed by warfarin tablets.

The guideline recommends the use of blood thinners (secondary prevention) for variable periods of time after an episode of PE, depending on the patient's risk of recurrence. In contrast to these two risk categories, treatment remains controversial in patients with intermediate-risk PE, that is patients who present with normal blood pressure but with ultrasound and laboratory findings which indicate beginning heart failure. A large European trial is currently underway to determine whether these patients need clot busters (like the high-risk category) or can be managed with blood thinners alone (like the low-risk category). The trial, entitled Pulmonary Embolism International Thrombolysis Study (PEITHO), is a European investigator-initiated and investigator-sponsored study whichis also supported by funds from the French and German Government.

The study began in early 2008 and has already recruited patients in six countries: France, Italy, Germany, Poland, Switzerland, Slovenia. A total of 64 patients have been enrolled so far. Another six countries will be initiated soon. The study plans to randomise as many as 1,000 patients until the end of 2010. It will thus be the largest thrombolysis trial in PE ever performed.