A critical review of the efficacy of 99mTc pyrophosphate in detecting myocardial infarction in 103 patients.

Patients imaged with 99mTc pyrophosphate for myocardial infarction between October 1975 and March 1976 were reviewed. There were 103 patients and 114 images obtained. The clinical criteria of either or electrocardiographic changes were used to validate a myocardial infarct. We experienced 92.4% true negatives, 68.7% true positives, 7.5% false positives and 31.3% false negatives. It technically compromised scans were exclude (those with blood-pool activity, overlying costal cartilage), the false-negative rate was 15.4%. These data show that the presence of a negative phosphate scan does not rule out the possibility of a recent small, less than 2.5-cm subendocardial myocardial infarction.