Myocardial scintigraphy with 123I-labelled heptadecanoic acid in patients with unstable angina pectoris.

Calculation of metabolic turnover rates with 123I-heptadecanoic acid (123I-HA) can detect regional myocardial ischaemia in patients with coronary artery disease. We have previously demonstrated different turnover rates in patients with stable angina compared with myocardial infarction. Twelve patients with unstable angina have now been studied: 8 patients showed imaging defects in 12 different myocardial regions and in 4 no defects were observed. Turnover rates were derived from time-activity curves and expressed in minutes half-time (t 1/2). All 12 regions with accumulation defects showed increased t 1/2 values (45.4 +/- 4.8 min) compared to normally perfused zones (29.1 +/- 3.6 min). The results suggest that the use of 123I-HA can identify ischaemic areas of myocardium in unstable angina and that the turnover of 123I-HA is different from that already established in the areas with infarction.