Clinical value of delayed thallium-201 myocardial imaging in suspected acute myocardial infarction

SUMMARY Fifty patients with acute chest pain had thallium-201 myocardial imaging performed three to six days after emergency admission to hospital. The image was abnormal in 20 out of 22 patients with acute transmural myocardial infarcts but in only 1 of 5 with acute subendocardial infarcts. Indis-tinguishable scan abnormalities caused by old infarcts were seen in 7 patients, and caused by myocardial ischaemia in 1 patient. A single thallium-201 myocardial scan some days after the onset of symptoms appears to be of little value in the clinical assessment of patients with suspected acute myocardial infarction. In only approximately 50 per cent of patients ad-mitted to hospital and later shown to have had an acute myocardial infarction can this diagnosis be made from the admission electrocardiogram (McGuinness et al., 1976) and in the remainder serial electrocardiograms and serum enzyme studies over the next few days are required. Even when these serial studies are complete, whether or not th