Absolute value of the difference of Tl-201 uptake between redistribution and rest is a specific marker of myocardial viability

Although Tl-201 rest redistribution SPECT is widely used to assess myocardi al viability, there is no agreement on the best prognostic marker of left v entricle contraction improvement after revascularization. More recent data suggest that not only rest or redistribution uptake but also reverse redist ribution patterns may serve to indicate the viability of myocardium. The ai m of this study was to define criteria (which include reversibility and rev erse redistribution) for viability testing and prediction of functional out come in Tl-201 rest redistribution SPECT. Twenty-five patients with left ve ntricle dyssynergy were studied before and after revascularization with Tl- 201 SPECT and echocardiography. Perfusion and contractility was assessed in a 16-segment model of the left ventricle. Out of 400 left ventricular segm ents, contraction disturbances of various degree of intensity (hypokinesis, akinesis and dyskinesis) were found by echocardiography in 107 segments. R evascularization was performed in 97 segments. In 57% of the segments, impr ovement of contraction was observed after PTCA or CABG. Perfusion was analy sed in the segments between segments with and without contraction improveme nt. In discriminant analysis, only the modulus of difference between rest a nd redistribution study greater than or equal to 10 was the common paramete r for hypo-, a- and dyskinetic segments to predict the functional recovery of left ventricle (LV) with the specificity of 93% and sensitivity of 78%. The modulus of segmental quantitative difference between redistribution and rest image is a new parameter adding specificity to Tl-201 rest redistribu tion SPECT in prediction of recovery of left ventricle function.