789-3 Does 99mTc-Sestamibi Gated-SPECT Provide Additional Information Over Ungated-Sestamibi and 201-TI Reinjection Imaging in Viability Assessment?

Sestamibi imaging is commonly believed to underestimate viability, however its optimal imaging characteristics are not completely explored. GatedSPECT permits assessment of an original marker of viability, which is the radionuclide myocardial wall thickening (RMWT), defined as increase in count density at end systole. Aims of this study were: 11 to compare 201-TI reinjection and ungated Sestamibi patterns to RMWT in territories with baseline segmental LV dysfunction and 2) to compare the accuracy of these 3 markers to predict functional recovery after successful PTCA. We studied 18 pts with segmental LV asynergies by contrast angiography in myocardial segments supplied by>75% stenotic coronary arteries. All pts were studied by thallium stress-redistribution-reinjection SPECT and by rest Sestamibi gated-SPECT. The assessment of LV performance was based on rest gated radionuclide angiography (RNA) performed before and 2 months after PTCA. The analysis of RMWT was done by visual evaluation in cine mode and by semiquantitative circumferential profile analysis. A 20 segments model was used for SPECT and a 9 segments for RNA. Pre and post PTCA global LV EF increased from 47±9% to 50±10 (p<0.05). The pts who failed to increase the EF by more than 3% had significantly more asynergic segments that failed to show RMWT compared to pts with EF improvement (3.9±3.8 vs 0.4±1.1, P<0.05). 21/360 segments (6%1 showed a severe 201-TI defect (>50% of the maximal uptake) after reinjection and 31 (9%) a severe detect by ungated-Sestamibi. Persistent RMWT was present in 7/21 (33%) and 14/31 (45%) segments respectively. In 61 of 162 segments (38%), there were severe regional wall motion abnormalities. Of these, 28 segments improved after PTCA and 33 did not. The sensitivities for functional improvement after PTCA for gated-SPECT, reinjection 201-TI and ungated-Sestamibi were 93, 86 and 64% respectively (gated vs ungated-Sestamibi, p<0.05). The corresponding specificities were 73, 45 and 61%, respectively (gatedSestamibi vs 201-TI reinjection, p<0.05). Thus, the persistence of RMWT, as detected by gated-SPECr. in asynergic areas predicts functional improvement after PTCA independent from the presence of severe defects by 201-TI reinjection or ungated-Sestamibi studies