Metabolic myocardial imaging with 123I-labeled heptadecanoic acid in patients with angina pectoris

Abstract

The potential value of 123I-heptadecanoic acid (123I-H degree A) in myocardial scintigraphy has recently been assessed in patients with acute myocardial infarction (AMI) by studying regional myocardial metabolism (Van der Wall et al. 1981 a). To determine the metabolic behavior of 123I-H degree A in patients with stable angina pectoris (AP) as well, 30 patients with AP were included in this study: 18 patients were exercised and 12 patients were studied at rest. Regional myocardial metabolism was evaluated by generating background subtracted time-activity curves, acquired by external detection over normally perfused and ischemic regions during a 30-min period after intravenous injection of 123I-H degree A. Following monoexponential curve-fitting, clearance rates were measured representing turnover rate (T1/2) of 123I-H degree A. The exercise group showed prolonged T1/2 values of 46.7 +/- 7.1 min (mean +/- SD) in ischemic regions and 28.7 +/- 3.6 min in normally perfused regions. The group at rest did not reveal any scintigraphic abnormalities and showed normal T1/2 values in all myocardial regions (29.1 +/- 4.7 min). Our observations of prolonged turnover rates in ischemic areas differ from the results of our recent study in patients with AMI, which demonstrated fast turnover rates in infarcted tissue. These data imply that 123I-H degree A permits the study of myocardial metabolism in patients with AP and the discrimination of normally perfused, reversibly ischemic (AP) and irreversibly ischemic (AMI) myocardium.