Correlations of Tc-99m pyrophosphate myocardial scintigraphy and the results of coronary-artery bypass surgery.

This study indicates that abnormal myocardial scintigrams with Tc-99m pyrophosphate tend to improve after coronary-artery bypass surgery, frequently changing from positive to normal. The significance of this change is uncertain. It does not correlate well with the clinical state but may simply reflect the natural course of myocardial scintigraphy in response to hospitalization, medical management, and presumably improved myocardial oxygenation. Postoperative myocardial scintigrams are useful in detecting perioperative infarction. ECG interpretation may be difficult in the immediate postoperative period and, in three cases, there were scintigraphic criteria of perioperative infarction without diagnostic changes on ECG. Patients with positive preoperative scintigrams, especially in association with Functional Class IV angina, are at increased risk during coronary-artery bypass surgery.