24-HOUR QUANTITATIVE THALLIUM IMAGING FOR PREDICTING BENEFICIAL REVASCULARIZATION

To determine the utility of 24-h thallium single-photon emission tomog raphic imaging for the assessment of myocardial viability, 40 patients with persistently decreased uptake on 3-h delayed imaging after exerc ise were studied before and after bypass surgery (n=34) or coronary an gioplasty (n=6). Wall motion improvement after revascularization was a lso analysed in 23 patients with respect to the segments with and with out 24-h redistribution. Of a total of 113 segments without redistribu tion at 3-h imaging after exercise, 62 (55%) demonstrated redistributi on at 24 h. After revascularization 57 (92%) of these 62 segments reve aled improvement of thallium uptake. On the other hand 40 (78%) of the 51 segments with persistently decreased thallium uptake until 24 h di d not show improvement of uptake after revascularization. Of the 15 se gments with >50% relative thallium uptake and without redistribution o n 24-h images, ten showed improvement of thallium uptake after revascu larization. Hence higher uptake even without 24-h redistribution may i ndicate viability. Regional wall motion improved in 22 of 23 segments with redistribution on 24-h images, and did not improve after revascul arization in 19 of 22 segments without redistribution at 24 h. These d ata suggest that 24-h late imaging with quantitative analysis may prov ide reliable information about reversible myocardial ischaemia in segm ents that demonstrate a fixed perfusion abnormality on conventional 3- h delayed imaging.