Implications of delayed image on simultaneous thallium-201/technetium-99m pyrophosphate dual emission computed tomography early after acute myocardial infarction

This study investigated whether Tl-201 and Tc-99m pyrophosphate dual rest-redistribution emission computed tomography (ECT) early after intracoronary thrombosis may provide supplementary information for the management of patients with acute myocardial infarction. Fifty patients who received intracoronary thrombolysis underwent simultaneous dual ECT 3 days after first acute myocardial infarction. All patients who had a Tc-99m pyrophosphate accumulation were selected. Tl-201/Tc-99m pyrophosphate overlap in the initial and delayed images early after intracoronary thrombolysis identified successful recanalization with sensitivities of 68% and 90%, specificities of 47% and 79%, positive predictive accuracies of 68% and 88%, negative predictive accuracies of 47% and 80%, and overall accuracy of 60% and 86%, respectively. The patients were divided into 3 groups according to the change in Tl-201 uptake from the initial image to the delayed image on dual ECT: 20 had no change in Tl-201 uptake (fixed type), 16 had increases in Tl-201 uptake (redistribution type), and 14 had decreases in Tl-201 uptake (reverse redistribution type). The number of patients with successful recanalization was significantly higher in the redistribution type or fixed type. In the redistribution type a frequency of reinfarction in the same infarcted area during the hospital course was significantly higher than in the other types (redistribution type vs reverse redistribuion type or fixed type), which was mainly due to the patients having high grade residual stenosis. Thus, a Tl-201/Tc-99m pyrophosphate overlap in the delayed image early after acute myocardial infarction can be used as an index for predicting successful early recanalization and probably viable myocardium. In addition, the redistribution patterns on Tl-201 ECT early after intracoronary thrombolysis can be helpful in identifying patients with successful early recanalization and a high risk subset. (author)