Redistribution of thallium at rest in patients with stable and unstable angina and the effect of coronary artery bypass surgery

To determine the significance of redistribution (RD) of thallium-201 (/sup 201/T1) at rest in patients with coronary artery disease, 14 patients with unstable angina (UA) and 15 patients with stable angina (SA) referred for angiography underwent serial myocardial /sup 201/T1 imaging over 3 hours. No patients were imaged during pain. Anterior and left anterior oblique images were divided into six segments for analysis. The extent of coronary artery disease and the /sup 201/T1 perfusion pattern were similar for UA and SA patients. In the 29 patients, 91 of 174 segments had decreased /sup 201/T1 uptake on the 10-20-minute images. At least one initial defect was present in 26 of 29 patients, but only 14 of 29 had ECG evidence of infarction. On delayed 3-hour images, 69 of 91 segments with diminished initial uptake showed RD, while 22 defects persisted. Angiography demonstrated that 66 of 69 segments with RD had significant (> 70%) corresponding coronary artery stenoses. Wall motion analyses of 63 segments with RD revealed that 52 were normal or hypokinetic and 11 were akinetic or dyskinetic. Of 13 persistent defects, six were normal or hypokinetic and seven akinetic or dyskinetic (p > 0.02). In 22 patients who underwent coronary bypass surgery, 37 of 48 segments (77%) with decreased initial /sup 201/T1 uptake and subsequent RD preoperatively reverted toward normal initial uptake postoperatively. In addition, 13 of 18 persistent defects preoperatively showed /sup 201/T1 uptake postoperatively.Thus, resting /sup 201/T1 defects may not represent myocardial scar. Patients with UA or SA may show RD of /sup 201/T1 at rest. Myocardial revascularization is usually associated with improvement in early /sup 201/T1 uptake in segments with initial defects and RD preoperatively.