Frequency and clinical significance of a variety of autoantibodies in patients with definite infective endocarditis.

BACKGROUND

Patients with infective endocarditis (IE) may present rheumatic manifestations concurrent with autoantibodies with low specificity, thus increasing misdiagnosis. Frequency of autoantibodies with high specificity remains unknown.

METHODS

Nineteen patients with definite IE were studied for low specificity (rheumatoid factor [RF], antinuclear antibodies, anti-Ro/SSA, anti-La/SSB, anti-ribonucleoproteins (anti-RNP) anticardiolipin [aCL], and anti-β2 glycoprotein 1) and high specificity (anti-cyclic citrullinated peptides [anti-CCPs], anti-double-stranded DNA, anti-Sm, anti-Scl70, and anticentromere) antibodies.

RESULTS

Frequency of RF was 68%; antinuclear antibodies, 47%; aCL/IgG, 58%; aCL/IgM, 47%; anti-β2 glycoprotein 1/IgG, 5%; and anti-Ro/SSA, 5%. Three patients had antiphospholipid syndrome-related antibodies in high titers, one of them also having pulmonary embolism. Except for anti-CCP (1 patient), other highly specific antibodies were absent.Rheumatoid factor of 100 UI/mL or greater and multifocal endocarditis were independently associated with in-hospital mortality.

CONCLUSIONS

Clinicians should need to be aware about the common presence of a variety of antibodies with low specificity but also the exceptional occurrence of anti-CCP antibodies in IE. Special attention to multifocal endocarditis and high RF is also suggested.