Technetium-99m pyrophosphate scintigraphy for the detection of acute myocardial infarction. How useful is it?

To evaluate the contribution of Tc-99m pyrophosphate scintigraphy (TPS) on the overall management of patients suspected of having acute myocardial infarction (AMI), hospital records of 58 consecutive patients who underwent TPS, were evaluated in depth. The results indicate that TPS was essential for the diagnosis of AMI in 16% of the patients. TPS was most rewarding in perioperative patients and in patients with borderline or uninterpretable electrocardiographic and enzyme changes. Also, in some cases, TPS was able to confirm or exclude the diagnosis of AMI prior to the confirmation by serial electrocardiograms (ECG) and serial enzyme changes. TPS was less rewarding in patients with clinically low index of suspicion for AMI. It may also be confusing in patients with high clinical likelihood of AMI and a history of prior myocardial infarction because of the possibility of persistently positive TPS in some of these patients. Considering the limitations of ECGs, the cardiac enzymes, and atypical clinical presentations in the patient population we evaluated, TPS appears to be fairly accurate when the scintigraphic findings are compared with the final diagnosis at the time of discharge from the hospital.