ANCA-positive infective endocarditis tied to longer disease duration, kidney injury

A significant number of patients with infective endocarditis have been found to have antineutrophil cytoplasmic antibody (ANCA), which is associated with longer disease duration, more frequent purpura, and kidney involvement, results of a study has shown.

A team of investigators conducted a retrospective study in a tertiary hospital in China from August 2012 to December 2021 to investigate the clinical implications of ANCA in infective endocarditis and highlight the diagnostic challenge in ANCA-positive patients with infective endocarditis.

Patients diagnosed with infective endocarditis who had available ANCA results were included in the analysis. Subsequently, clinical and pathological characteristics were compared with ANCA-positive and ANCA-negative patients.

Of the 237 patients who met the eligibility criteria, 43 (18.1 percent) were ANCA-positive, chiefly c-ANCA/anti-PR3. In addition, these patients had longer disease duration (p=0.004), more frequent purpura (p=0.015), macrohaematuria (p=0.002), proteinuria (p=0.043), acute kidney injury (p=0.004), and rapidly progressive glomerulonephritis (p=0.010) than ANCA-negative counterparts.

The investigators then reviewed the histologic findings of eight patients with infective endocarditis-related glomerulonephritis. Among ANCA-positive patients with infective endocarditis, two presented with pauci-immune necrotizing and crescentic glomerulonephritis. Of note, 18 percent of ANCA-positive patients had been misdiagnosed as having ANCA-associated vasculitis.

“ANCA-positive infective endocarditis may mimic ANCA-associated vasculitis, and the differential diagnosis is challenging,” the investigators said. “Whether ANCA is pathogenic in infective endocarditis-associated small vessel vasculitis requires further study.”