Ab1391 Immunopathological Manifestations of Infective Endocarditis

Background: Infectious endocarditis has many immunopathological manifestations, both organ and laboratory, which can mimic inflammatory rheumatic diseases (RD), such as systemic vasculitis, rheumatoid/reactive arthritis, Still's disease, systemic lupus erythematosus, antiphospholipid syndrome, etc. It can be especially complex differential diagnosis with RD occurring with non-infectious endocarditis. Delay in diagnosis leads to delay in initiation of antibiotic therapy; on the other hand, misdiagnosis of RD and administration of immunosuppressive therapy can have catastrophic consequences for patients with active infection. Methods: The study included 50 patients with infective endocarditis, 11 of them had an acute course, and 39 had a subacute course. Results: Damage to the musculoskeletal system was observed in 60% of patients: arthritis was detected in 20%, arthralgia in 38%, myalgia in 14%, tendinitis in 18% of patients. The duration of arthritis during antibiotic therapy was, on average, 7.5 + 4 days, arthralgia - 15 + 12 days. 3 patients had persistent long-term arthralgia (up to 3 months), with the infectious process already stopped. Organ pathology: nephritis was diagnosed in 28%, pericarditis in 18%, vasculitis in 18%, myocarditis in 12% of patients. Nephritis was more often observed with staphylococcal infection than with streptococcal infection (56% and 9%, respectively), p = 0.04, and also more often with the acute course of the disease, compared with subacute (57% and 23%, respectively). Myocarditis and pericarditis were also more common in acute compared with subacute (29% and 9%; 43% and 14%, respectively). In 88% of patients, immunological disorders were detected during laboratory testing: positive RF in 72%, increased a-DNA in 57%, ANA in 36% (in low and medium titers), cryoglobudins in 44% of patients (including high (+4) – in 23%). Hypergammaglobulinemia was recorded in 58% of patients. Patients with nephritis had positive ANA, cryoglobulinemia, and high RF significantly more often than others, p<0.05. With the development of myocarditis, positive ANAs were more often detected (50% and 30%, respectively). Conclusion: Infective endocarditis has many symptoms, clinical and laboratory, overlapping with RD, which can lead to diagnostic errors. Infective endocarditis should always be considered in the differential diagnosis of RD, especially those occurring with endocarditis. Blood cultures for sterility, ECHO-CG, and PET-CT are often necessary for a correct diagnosis. If a patient with infective endocarditis has a positive RF, ANA and cryoglobulins, then the risk of developing glomerulonephritis is very high. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests: None declared.