Clinical significance of early redistribution of the exercise-induced thallium-201 defect in ischemic heart disease]

This study clarified thallium-201 (Tl) kinetics in the early stage after exercise in patients with ischemic heart disease (IHD). Tl was administered for 39 patients with IHD and eight normal subjects during maximal exercise. Immediately after exercise, dynamic data were obtained using a double slant-hole collimator at one frame/2 min for a 20 min period. The data of 10 frames (20 min) were spatially smoothed, and semiquantitative segmental analyses of the uptake and kinetics of Tl were performed by computer. In eight normal subjects, Tl uptake was uniform throughout the continuous 20 min, and Tl activity was unchanged throughout the 20 min period after exercise. Among 39 patients with IHD, 39 had Tl defects in the first frame (initial defect). Among 39 initial defects, 15 (38%) showed complete or partial early redistribution as early as 20 min and Tl activity in the defect increased (10.5 +/- 1.5%) over the 20 min period. Early redistribution occurred in 10 (43%) of 23 patients with effort angina and in five (83%) of six patients with variant forms of angina, but in no patients with myocardial infarction. Patients with early redistribution showed a greater frequency either of good collateral vessels or of mild stenosis of the coronary artery, compared with those who had no early redistribution. In conclusion, analysis of Tl kinetics in the early stages after exercise can provide important information about the coronary perfusion state during recovery from transient ischemia, and early redistribution may be a sign of preserved hyperemic flow in the ischemic region.