The relationship between reverse redistribution of 99mTc-tetrofosmin in sub-acute phase and left ventricular functional recovery in chronic phase in patients with acute myocardial infarction.

Objective: The purpose of this study was to clarify the relationship between reverse redistribution (RRD) of (99m)Tc-tetrofosmin ((99m)Tc-TF) and left ventricular functional recovery in patients with acute myocardial infarction (AMI).

Methods: We studied 21 patients with AMI who underwent direct percutaneous coronary intervention (PCI). (99m)Tc-TF-gated single-photon emission computed tomography (SPECT) was performed at rest in the sub-acute and chronic phases. Imaging data were acquired at 30 min (early images) and 3 h (delayed images) after injection. Defect score, regional relative uptakes of (99m)Tc-TF (%uptake), and regional wall thickening (WT) were calculated using the 20-segment model. We measured left ventricular ejection fraction (LVEF) and defined DeltaLVEF as change in LVEF. Summed defect score was calculated by adding the scores of 20 segments on early and delayed images. Summed washout score (SWS) was derived as the difference between early and delayed scores. We defined that SWS was more than 1 point as individual RRD (I-RRD). In each segment, regional RRD (R-RRD) in the sub-acute phase was calculated as %uptake on early images minus %uptake on delayed images in the sub-acute phase. DeltaWT was defined as change in WT from the sub-acute phase to chronic phase. We defined that R-RRD and DeltaWT were higher than 1SD on the control map as R-RRD (+) and change of WT (+).

Results: All patients were divided into two groups according to the presence of I-RRD. DeltaLVEF was significantly higher in I-RRD (+) than in I-RRD (-) (14.5 +/- 12.1 vs. 0.0 +/- 3.9%, p < 0.01). We analyzed 162 segments as at-risk areas among a total of 420 segments. In total of R-RRD (+), 75 of 96 segments (78%) had change of WT (+), while this was observed in only 13 of 66 segments (20%) in total of R-RRD (-) (p < 0.0001). In addition, there was a significant correlation between R-RRD in the sub-acute phase and change in %uptake on delayed images from the sub-acute phase to chronic phase in at-risk areas (r = 0.584, p < 0.001).

Conclusion: These findings suggested that quantitative evaluation of RRD by gated (99m)Tc-tetrofosmin SPECT in the sub-acute phase can predict recovery of left ventricular function in the chronic phase with higher accuracy in patients with AMI who underwent direct PCI.