Recurrent pulmonary embolism

On Monday we discussed a patient with recurrent unprovoked DVT/PE. While we often think of venous thromboembolism (VTE) as an acute issue (which it is when we're managing it in the ER!), there is also a chronic component - the risk of recurrence after 5 years is 20–25%. It is more than 25% in patients with unprovoked events, like our patient.

Treatment for VTE is anticoagulation, initially with heparin and for several months thereafter with low-molecular weight heparin or warfarin. Anticoagulation has its own risks - up to 3% per year risk of bleeding, and likely higher rates in "real life". For this reason, it is important that we understand and estimate the risk of recurrence of VTE in our patient population, to avoid unnecessary anticoagulation. Only patients at high-risk of recurrence should be anticoagulated after their initial 3-6 months of anticoagulation therapy - so how do we assess this?

Here are some factors that place patients at higher risk for recurrence:

No predisposing factor (ie unprovoked)

More than two thrombotic events

Continued estrogen use

Pulmonary embolism or proximal deep vein thrombosis

Male (nearly 4x higher than women - with unprovoked VTE!)

Vena cava filter

Cancer (early recurrence)

Lastly, we often discuss (as we did in AM report) the hypercoagulable states and their associated laboratory markers - factor V Leiden, antithrombin III deficiency, protein C and protein S deficiencies, prothrombin mutation, and antiphospholipid antibody syndrome, among others. There is currently no evidence to suggest that testing for these markers (and deciding treatment duration based on the the results) makes any difference in recurrence of events - and it commits some people to lifelong anticoagulation. This seems to suggest that we shouldn't be measuring them routinely - food for thought!

Other markers with some evidence (and ongoing studies) are the utility of the D-Dimer, measured 1-month after discontinuing anticoagulation. High levels are associated with higher risk of recurrence. Other prediction models combining a variety of factors are being investigated.

All this to say - it's not as simple as we thought!

See here for a great review on this subject.

Palpable Purpura

Last week we discussed a young man with IBD, with recurrent episodes of palpable purpura. It was ultimately thought that he had a post-viral leukocytoclastic vasculitis.

Palpable purpura is a rare finding, but can be dramatic. It is important to recognize because it can be a harbinger of serious illness. Purpura is caused by necrosis, antigen-antibody complex deposition, and fibrin deposition on or between endothelial cells. Although it is classically associated with cutaneous small-vessel vasculitis, as in this patient, it is also associated with embolic, infectious, and malignant causes.

Here is a general differential diagnosis (note vasculitidies comprise the bulk of the list):

Inflammatory

Cutaneous vasculitis

Hypersensitivity vasculitis (ie medications-induced)

Henoch-Schonlein purpura

Polyarteritis nodosa

Granulomatous vasculitis (Wegener's granulomatosis, Churg-Strauss vasculitis)

Cutaneous vasculitis associated with a collagen vascular disease (e.g., systemic lupus erythematosus, rheumatoid arthritis)

Giant cell arteritis

Mixed cryoglobulinemia

Hyperglobulinemic purpura

Infectious

Subacute bacterial endocarditis

Meningococcemia (usually petechial)

Noninflammatory

Trauma

Amyloidosis

Senile purpura

Scurvy

Sweet’s syndrome

Kaposi’s sarcoma

Toxins

Unfortunately not available online, here is the reference: Am Fam Physician. 1995 Oct;52(5):1355-62.