Value of Tc-99m Pyrophosphate Myocardial Infarction Imaging in the Detection of Acute Myocardial Infarction - In the Cases with Nondiagnostic Electrocardiogram -

摘要

The traditional diagnostic methods available for diagnosis of acute myocardial infarction such as electrocardiogram and serum enzyme analysis have well known linitations in clinical application and identifying the acute myocardial infarction. Therefore it does seem important to develop additional noninvasive means of identifying the presence of myocardial necrosis which may be used in conjunction with standard techniquens for infarct recognition. The purpose of this study was to define the diagnostic usefulness of myocardial infarct imaging with technetium-99m stannous pyrophosphate(Tc-99mPYP) which is introduced in clinical application recently. The study was performed in 41 patients with chest pain thought to be due to acute myocardial infarction and with nondiagnostic electrocardiogram by serial determinations of serum creatine kinase -MB (CK-MB) isoenzyme and lactic dehydrogenase(LDH) isoenzyme-1/-2 ratio accompanying with Tc-99m PYP myocardial imaging. The results are as follows: 1) Of the studied 41 patients, none showed false positive and 3 false negative Tc-99mPYP myocardial scintigraphic finding in the diagnosis of acute moycardial infarction. On the other hand, serum Ck-MB isoenzyme and LDH-1/-2 ratio showed 10 and 1 false positive, and none and 4 false negative findings, respectively. 2) The 3 patients who couldn't be identified by Tc-99mPYP myocardial imaging technique had subendocardial infarction in all. 3) Of the 10 patients wih false positive elevation in serum Ck-MB isoenzyme determinations, 5 patients were postcardiotomy syndrome, 1 after cardiopulmonary resuscitation due to cardiac arrest, 1 after cardioversion, 1 unstable angina, 1 after coronary bypass surgery and 1 after carotid endarterectomy. In all of these patients, serum CK-MB isoenzyme levels were within 5-10% of total serum CK level. In conclusion, Tc-99mPYP myocardial imaging technique appears to be very specific and high sensitive diagnostic tool for detecting acute myocardial infarction as compared with serum enzyme analysis. Tc-99mPYP myocardial scintigraphy in addition to serum CK-MB isoenzyme determination which it is useless as an isolated finding due to the poor specificity may be extremely valuable in confirming the diagnosis of myocardial infarction, especially in the cases with nondiagnostic electrocardiogram.