Immunoscintigraphy using technetium-99m-labeled anti-NCA-95 antigranulocyte antibodies as an adjunct to echocardiography in subacute infective endocarditis

Department of Cardiology and Pulmonology, Georg August University, Gottingen, Germany.

OBJECTIVES. This study was performed to assess the clinical value of immunoscintigraphy in subacute infective endocarditis. BACKGROUND. Radiolabeled granulocytes can reveal inflammatory lesions. METHODS. Using technetium-99m-labeled anti-NCA-95 anti-granulocyte antibodies, planar scintigraphy and single-photon emission computed tomography of the thorax were performed in 72 consecutive patients with suspected endocarditis. Each patient also underwent transthoracic and, if findings were negative, transesophageal echocardiography. RESULTS. Thirty-three patients were found to have endocarditis on the basis of clinical criteria (surgical confirmation in 17 patients), and the remaining 39 served as control subjects. Initial scintigraphy was true positive in 26 patients (sensitivity 79%) and false positive in 7 (specificity 82%). Echocardiography was true positive in 29 patients (sensitivity 88%) and false positive in 1 (specificity 97%). Scintigraphy was positive in the four patients with false negative echocardiography, and echocardiography was positive in the seven patients with false negative scintigraphy. Thus, the combination of scintigraphy and echocardiography yielded a sensitivity of 100% and a specificity of 82%. In 10 of the 11 patients with two to three follow-up studies, scintigraphy became negative parallel to clinical improvement, indicating decreasing floridity of the inflammatory process. CONCLUSIONS. Immunoscintigraphy in patients with subacute infective endocarditis provides valuable diagnostic information in equivocal echocardiographic findings and may be used to monitor antibiotic therapy.