Sequential myocardial scintigraphy with technetium-99m stannous pyrophosphate following myocardial infarction

Studies have shown that technetium-99m stannous pyrophosphate (Tc-PPi) is effective for the detection and imaging of acute myocardial infarction. Positive Tc-PPi myocardial scintigrams, however, have been reported in patients with other forms of heart disease and no evidence of recent myocardial infarction. To help define the usefulness of this test, we undertook a prospective study to ascertain when Tc-PPi myocardial scintigrams return to normal after myocardial infarction. Twenty patients with acute myocardial infarction were followed with Tc-PPi scintigrams at 1 and 2 wk, and 1, after infarction. The serial scintigrams revealed that a) 15 of 18 scintigrams were positive within the first week after infarction, b) the number of markedly positive scintigrams decreased promptly after the first week, and c) some scintigrams (11 of 18 at 1 mo, and 3 of 18 at 9 mo) remained positive throughout the study. The possible explanations for persistently positive scintigrams are discussed. Persistently positive scintigrams may hinder the usefulness of Tc-PPi myocardial scintigraphy for the diagnosis of acute myocardial infarction in patients who have had a myocardial infarction within the previous 9 mo.