Monoclonal Fab antimyosin in cardiac imaging.

Antimyosin is an Fab fragment of a murine monoclonal antibody directed against human heavy chain myosin. It is specific for myocyte necrosis. When linked via diethylenetriaminepentaacetic acid to indium-111, the agent has good imaging properties. With planar imaging, it has demonstrated high sensitivity and specificity for detecting and localizing acute myocardial infarction (MI). In addition, studies of dual isotope (indium-111 antimyosin/thallium-201) SPECT imaging at rest in the early in-hospital post-MI period appear to be predictive of further ischemic events. Antimyosin imaging also shows promise as a noninvasive tool to aid in the diagnosis and assessment of prognosis in cardiac transplant rejection and myocarditis. There is no evidence to date for allergic reactions to the murine protein.