LEFT-VENTRICULAR DYSFUNCTION IN CORONARY-ARTERY-DISEASE - COMPARISON BETWEEN REST-REDISTRIBUTION THALLIUM-201 AND RESTING TECHNETIUM-99M METHOXYISOBUTYL ISONITRILE CARDIAC IMAGING

Background. We compared rest-redistribution thallium 201 and resting technetium 99m methoxyisobutyl isonitrile (MIBI) cardiac imaging in 29 men with angiographically proven coronary artery disease and regional ventricular dysfunction. Left ventricular ejection fraction at radionuclide angiography was 35% +/- 9%. Methods and Results. Regional left ventricular wall motion was assessed on gated Tc-99m MIBI images according to a 3-point scale (0 = normal, 1 = hypokinetic, 2 = akinetic or dyskinetic). Tl-201 and Tc-99m MIBI uptake values were analyzed quantitatively. A total of 435 myocardial segments were classified on the basis of wall motion analysis into three groups: group 1 (normal wall motion; n = 201), group 2 (hypokinetic; n = 132), and group 3 (akinetic or dyskinetic; n = 102). Tl-201 and Tc-99m MIBI uptake values were significantly higher in groups 1 and 2 compared with group 3 (p < 0.05) and in group 1 compared with group 2 (p < 0.05). When Tl-201 and Tc-99m MIBI uptake values were directly compared, no significant differences in groups 1 and 2 were observed. In group 3, Tc-99m MIBI uptake (67% +/- 14%) was significantly lower (p < 0.001) than initial (72% +/- 11%) and delayed Tl-201 uptake (73% +/- 12%). Conclusion. Thus rest-redistribution Tl-201 and resting Tc-99m MIBI cardiac imaging reflect the severity of left ventricular dysfunction in coronary artery disease. However, in segments with severely impaired regional ventricular function, Tl-201 uptake is significantly higher than Tc-99m MIBI uptake.