Endocarditis: Infection, Antiphospholipid Syndrome, or Something Else?

Wangemail LW, Noël B, Descloux E, Baron DW. Antiphospholipid syndrome: an important differential diagnosis for culture-negative endocarditis.The American Journal of Medicine. 2014 Accepted manuscript. doi: http://dx.doi.org/10.1016/j.amjmed.2014.11.010

This case study discusses a 37-year-old woman suspected of having cardioembolic stroke, based on results of transesophageal echocardiography, after she presents with sudden-onset persistent left-sided weakness.

Her poor dentition raises a suspicion of infective endocarditis. However, serology and blood cultures are negative for microorganisms.

Procoagulant screening identifies lupus anticoagulant, anticardiolipin IgG antibodies, and anti-β2 glycoprotein I IgG antibodies. The vasculitic screen reveals a positive antinuclear antibody titer, but is negative for a number of antibodies and antigens. 

The physicians render a tentative diagnosis of nonbacterial thrombotic endocarditis due to antiphospholipid syndrome, pending interval testing 12 weeks later.

A vasculitic screen 4 months after the initial presentation confirms the diagnosis of nonbacterial thrombotic endocarditis. She is started on hydroxychloroquine.

After deterioration of her renal function, kidney biopsy shows mild mesangioproliferative changes with focal segmental sclerosis.

This fulfills 4 of 11 criteria for systemic lupus enrytematosus: positive antinuclear antibodies, hematological abnormalities, renal abnormalities, and positive antiphospholipid antibodies.

The authors point out the need to be aware that the initial diagnosis may actually be secondary to the actual causative condition.