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

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Abstract
To determine the significance of redistribution (RD) of 201Tl 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 201Tl imaging over 3 h. No patients were imaged during pain. Anterior and left anterior oblique images were divided into 6 segments for analysis. The extent of coronary artery disease and the 201Tl perfusion pattern were similar for UA and SA patients. In the 29 patients 91 of 174 segments had decreased 201Tl uptake on the 10-20 min images. At least 1 initial defect was present in 26 of 29 patients, but only 14 of 29 had ECG evidence of infarction. On delayed 3 h images 69 of 91 segments with diminished initial uptake showed RD; 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, 6 were normal or hypokinetic and 7 akinetic or dyskinetic (P > 0.02). In 22 patients who underwent coronary bypass surgery, 37 of 48 segments (77%) with decreased initial 201Tl uptake and subsequent RD preoperatively reverted toward normal initial uptake postoperatively. Of 18 persistent defects preoperatively 13 showed improved 201Tl uptake postoperatively. Resting 201Tl defects may not represent myocardial scar. Patients with UA or SA may show RD of 201Tl at rest. Myocardial revascularization is usually associated with improvement in early 201Tl uptake in segments with initial defects and RD preoperatively.