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Three Part Question

In [a patient with suspected acute pulmonary embolus] is [aspirin] effective in [reducing morbidity and mortality]?

Clinical Scenario

A 50 year old woman presents to the emergency department with shortness of breath and pleurtic chest pain, following a flight from Australia. Examination is unremarkable except for tachypnoea and mild hypoxia. CXR is also normal, so you aim to treat for suspected pulmonary embolus. You know that aspirin is used in the treatment of other acute thromboembolic conditions eg CVA or MI, and in the prophylaxis of DVT/PE. You wonder if aspirin would also be beneficial in the treatment of acute PE?

Search Strategy

Medline 1966-12/04 using the OVID interface and The Cochrane Library, Issue 3, 2004.
Medline: [exp ASPIRIN OR aspirin.mp OR exp Antifibrinolytic Agents OR Acetylsalicylic acid.mp] AND [exp Pulmonary Embolism OR pulmonary embol$.mp OR PE.mp] LIMIT to human AND English language.
Cochrane:Aspirin or Pulmonary Embolism.

Search Outcome

267 papers were found. The majority discussed the use of aspirin in prophylaxis. None of these papers addressed the question of use in acute PE.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses

Comment(s)

Poullis suggests in a letter that aspirin administration after diagnosis of PE in combination with heparin could have beneficial effects but needs further study. Although this question has been raised many times in our clinical practice there appears to be little discussion in the literature. One possibility may be, as some haematologists suggest, that aspirin is more likely to be useful when the final occluding event is a platelet clump. This is more common in the resence of arterial atheromatous plaques which rupture and attract platelets to the site. This occurs in coronary artery disease and in the carotid vessels where aspirin is advocated. In venous disease, where the vessel walls are relatively smooth and stasis is more important, clots are more likely to occur as a result of the activation of the clotting system. Another consideration is that patients with proved PE are generally anticoagulated initially with heparin, and then with warfarin. The additional benefit of aspirin is therefore likely to be small. Such a small benefit must be weighed against the additional bleeding complications from concomitant aspirin use.

Clinical Bottom Line

There is no published evidence to support the use of aspirin in the treatment of acute pulmonary embolism.

References

1. Poullis M. Aspirin for the treatment of pulmonary embolism: vasoconstriction versus physical obstruction. American Heart Journal. 140(4):E22, 2000 Oct.