The clinical pattern differentiates ANCA-positive infective endocarditis patients from ANCA-associated vasculitis patients: a 23 years' retrospective cohort study in China and follow-ups.

OBJECTIVES: Patients with infective endocarditis (IE) may present rheumatic manifestations concurrent with various autoantibodies and thus mimic antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). This study aims to characterize the specific features in a long-term cohort of ANCA-positive IE patients and to perform comparative analysis with primary AAV patients. METHODS: We performed a retrospective thorough review of 475 consecutive IE patients over 23 years, identifying 22 patients positive for proteinase 3 and/or myeloperoxidase and 36 treatment-naïve AAV patients. The clinical, laboratory, and follow-up data were collected to perform comparative analysis. RESULTS: Our study illustrated that ANCA-positive IE patients were younger and had a shorter duration than AAV patients. Pulmonary lesions, ENT signs, peripheral neuropath, and proteinuria were more commonly seen in AAV patients, while heart valve involvement, spleen enlargement, and cerebral hemorrhage were more typical for IE patients (all p < 0.05). Besides, ANCA-positive IE patients presented a higher level of PR3-ANCA but lower C3 (both p < 0.05). Hyperleukocytosis and thrombocytopenia were more frequently found in AAV patients (both p < 0.05). No significant difference was noticed in the survival rate. CONCLUSIONS: Our study urges the early differential diagnosis of IE in ANCA-positive patients. It supports the claim that ANCA-positive IE patients and AAV patients do not share the same clinical spectrum. Echocardiography, serological profiles, and evaluation of multi-organ involvement might be required to improve diagnostic accuracy. Key Points •Early differential diagnosis of ANCA-positive IE from AAV is challenging even for expert rheumatologists. •Our study is so far one of the largest to include 22 ANCA-positive IE patients in one single center and spanning over 23 years. It is also the first study to include both ANCA-positive IE patients and AAV patients in one center. •Our study aides to identify a clinical picture to differentiate ANCA-Positive IE Patients from AAV Patients.