The specificity of pyrophosphate myocardial scintigrams in patients with prior myocardial infarction: concise communication.

Fifty-five patients with old (9 days to 10 yr) transmural infarcts but with no evidence of recent infarction, were imaged with Tc-99m pyrophosphate. Discrete uptake was rare in the setting of an old infarct. Diffuse uptake was neither sensitive to, nor specific for, acute infarction. Prior infarction will rarely cause diagnostic error if the discrete pattern is required for a positive diagnosis.