Identification of reversible ischaemia after acute myocardial infarction using thallium tomography with early and delayed imaging after resting injection.

Abstract

We studied 30 patients 6 weeks after first myocardial infarction in order to compare early and delayed imaging after resting injection of thallium for the detection of viable myocardium. Twenty-six of the 30 patients studied had received thrombolysis. Conventional stress and redistribution thallium tomography was followed by a resting injection of thallium with imaging immediately after in all patients and 3 h later in a subgroup of 15 patients. Thallium uptake was graded semi-quantitatively in each of nine myocardial segments. Eighty-eight of the 270 segments had a fixed defect on redistribution imaging, 40 (45%) of which had improved uptake in the immediate reinjection images. Only 9 of 135 (6%) segments with fixed defects on immediate reinjection imaging showed additional uptake with delayed reinjection imaging. These data suggest that imaging early after thallium reinjection is of value in the detection of reversible ischaemia after infarction, but that delayed reinjection imaging offers little additional benefit.