Reverse redistribution in resting Thallium-201 myocardial scintigraphy in chronic coronary artery disease: An index of myocardial viability

Abstract

The aim of this study was to evaluate whether segments with reverse redistribution on rest-redistribution 201 Tl scintigraphy represent viable tissue or scar. Methods : Nineteen patients (17 men, 2 women ; mean age 53 ± 8 yr) with coronary artery disease underwent rest-redistribution 201 Tl study before coronary revascularization. Regional 201 Tl uptake was analyzed quantitatively. Regional left ventricular wall motion was assessed before and after coronary revascularization using two-dimensional echocardiography and a three-point scale (1 = normal, 2 = hypokinetic, 3 = akinetic/dyskinetic). Two patterns of reverse redistribution were identified : pattern with normal 201 Tl uptake in rest and abnormal in redistribution images and pattern with abnormal 201 Tl uptake in rest and a significant decrease in redistribution images. Results : Of the 247 segments analyzed, 85 were classified as normal, 37 as reversible defects, 83 as fixed defects and 42 as reverse redistribution (19 RR-A, 23 RR-B). Segments with RR-A differed from those with RR-B in wall motion score (1.4 ± 0.7 versus 2.0 ± 1.0). Electrocardiographic Q-waves were present in 26% of segments with RR-A and in 57% of segments with pattern B. After revascularization, all dyssynergic segments with pattern A showed improved wall motion, while only 40% of segments with pattern B and abnormal wall motion had such improvement. Conclusion : Our results suggest that dyssynergic segments with pattern A should be considered viable, while more caution should be used in classifying those with pattern B.