Download A brief discussion of submassive pulmonary embolism

A brief discussion of submassive pulmonary embolism
The best that can be said for the idea of treating submassive pulmonary
embolism (PE) with thrombolytic therapy is that it is unsupported by the available
literature, which is very limited.
A submassive PE is one which does not cause hypotension but produces
changes on echocardiography, particularly on right heart strain. This is
suggestive of increased pulmonary pressure. Massive PE is commonly defined
as one that does cause hypotension. Note that these definitions do not
necessarily relate to the actual size of a PE or total clot burden. It should also be
noted that literature can be found using other definitions. These patients might be
at increased risk for worse outcomes than those without such changes on
echocardiography (Grifoni 2000).
Recent reviews of this topic (Worster 2007, Ramakrishnan 2008) have concluded
that there is no scientific support for thrombolytic therapy in such cases. In
fairness, however, it should be noted that there is limited primary research and
existing randomized trials are small. While they do not demonstrate a benefit to
thrombolytic therapy, neither do they exclude the possibility, as they are probably
underpowered to do so.
The testimony under review was given in July of 2005. The witness seems to
frequently reference Rosen’s Emergency Medicine: Concepts and Clinical
Practice. The 5th edition was published in 2002 and seems highly likely to be the
one referred by the witness (a 6th edition was published in 2006). The 5th edition
states that patients with submassive PE should be treated with thrombolytic
therapy. The reference cited for this statement (Jerjes-Sanchez 1995) does,
indeed, seem to show a benefit to streptokinase in submassive PE (this paper
defines “massive” PE according to the number of pulmonary segments occluded
on V/Q scanning). However, the very small number of patients, (eight) and the
clinical differences between the treatment and control groups would cause any
critical reader to question the accuracy of the results.
References
Grifoni, S. et al., Short-term clinical outcome of patients with acute pulmonary
embolism, normal blood pressure, and echocardiographic right ventricular
dysfunction. Circulation. 2000. 101:2817.
Jerjes-Sanchez, C. et al., Streptokinase and Heparin versus Heparin Alone in
Massive Pulmonary Embolism: A Randomized Controlled Trial. Journal of
Thrombosis and Thrombolysis. 1995. 2:227.
Ramakrishnan, N., Thrombolysis is not warranted in submassive pulmonary
embolism: a systematic review and meta-analysis. Critical Care and
Resuscitation Journal. 2008. 9:357.
Worster, A. et al., Thrombolytic Therapy for Submassive Pulmondaye Embolism?
Annals of Emergency Medicine. 2007. 50:78.