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Pulmonary embolism in hospital practice

BMJ 2006; 332 doi: https://doi.org/10.1136/bmj.332.7534.156 (Published 19 January 2006) Cite this as: BMJ 2006;332:156

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Heparin-induced thrombocytopenia and thrombosis as a cause of pulmonary embolism should not be forgotten

Dear Sir

I was reading this article with interest. Dr Robinson wrote a faily
good review. However, she did not mention anything on a not uncommon
acquired prothrombotic condition, "heparin-induced thrombocytopenia and
thrombosis". With so many patients receiving heparin for deep vein
thrombosis prophylaxis as well as for therapeutic purposes (e.g. acute
coronary syndromes), we frequently see heparin-induced thrombocytopenia
(HIT) which classically presents with thrombocytopenia or 50% drop in
baseline platelet count on days 5-14 after exposure or perhaps earlier if
the patient was exposed to heparin in the past 100-120 days. 50% of HIT
leads to thrombosis including pulmonary embolism. Diagnosis is confirmed
by heparin-platelet factor 4 antibody by ELIZA and/or serotonin release
assay.

The importance of this important clinical syndrome (HIT) is that
management of pulmonary embolism in this setting is different. These
patients must be treated with direct thrombin inhibitors such as
argatroban or lepirudin instead of heparin. Warfarin should not be started
straight away as it blocks vitamin K synthesis and can worsen
prothrombotic state and can cause warfain-induced skin necrosis or
worsening of the underlying thromboembolic process.

If someone was recently on heparin for various reasons and presents
with acute pulmonary embolism and thrombocytopenia or 50% drop in baseline
platelet count, heparin-induced thrombocytopenia and thrombosis should be
seriously considered as a differential diagnosis and should be treatment
with direct thrombin inhibitors. Warfarin should be started a few days
later.

References:

1. Kelton JG, Warkentin TE: Heparin-induced thrombocytopenia: a
historical perspective. Blood, 112(7):2607-16

2. Serasli E, Antoniadou M, Tsara V, et al. Successful management of
acute thromboembolic disease complicated with heparin-induced
thrombocytopenia type II (HIT II): a case series. Thromb J, 2;6:9. 2008

3. Prechel M, Walenga JM: The laboratory diagnosis and clinical
management of patients with heparin-induced thrombocytopenia: an update.
Semin Thromb Hemost. 34(1):86-96, 2008

Competing interests:
None declared

Competing interests: No competing interests

02 March 2009
Thein H Oo
Attending Physician/Consultant in Hematology & Medical Oncology, Assistant Professor of Medicine
St Elizabeth's Medical Center, Tufts University School of Medicine, Boston, USA