Reverse Redistribution Phenomenon on Rest 99mTc-Tetrofosmin Myocardial Single Photon Emission Computed Tomography Involves Impaired Left Ventricular Contraction in Patients With Acute Myocardial Infarction

Abstract

yocardial perfusion scintigraphy using as the flow tracer has been widely applied for the evaluation of myocardial ischemia and viability in patients with myocardial infarction. 1 Simultaneous evaluation of left ventricular (LV) wall motion and LV myocardial perfusion provides more information for this purpose, but as 201 Tl is not suitable as the tracer for electrocardiograph (ECG)-gated single photon emission computed tomography (SPECT), which is used for elucidating LV wall motion, echocardiography and/or left ventriculography have been the alternative techniques. 2,3 However, using a technetium (Tc)-labeled myocardial perfusion tracer, technetium-99m ( 99m Tc)-tetrofosmin, as well as 99m Tc-sestamibi allows simultaneous assessment of myocardial perfusion and LV function by ECG-gated SPECT because once these tracers are taken up by the myocardium, then the clearance is relatively slow and redistribution does not occur for several hours. [4][5][6] Several investigators have reported that in patients with acute myocardial infarction (AMI) after reperfusion therapy, myocardial imaging with 99m Tc-tetrofosmin or 99m Tcsestamibi shows a reverse redistribution (RR) phenomenon, 7-9 similar to that observed on 201 Tl scintigraphy in such patients. [10][11][12][13][14][15] The clinical significance of the RR of 201 Tl has been vigorously investigated, 10-15 compared with that on 99m Tc-tetrofosmin scintigraphy, which has not been fully elucidated. Thus, we used ECG-gated myocardial SPECT to investigate this issue in patients with AMI from the viewpoint of LV wall thickening after exercise. Methods PatientsWe studied 25 consecutive patients (17 men, 8 women, age 48-80 years) with AMI who underwent 99m Tc-tetrofosmin myocardial SPECT at rest approximately 3 weeks after the onset of infarction. Patients who had a prior myocardial infarction and/or coronary artery bypass surgery were excluded from the study. All the study patients underwent exercise stress ECG-gated SPECT with 99m Tc-tetrofosmin within 1 week of the rest study, and then selective coronary angiography was carried out. In those patients who did not Circ J 2003; 67: 830 -834 (Received February 10, 2003; revised manuscript received June 9, 2003; accepted July 9, 2003 The purpose of this study was to investigate the clinical significance of the reverse redistribution (RR) phenomenon on technetium-99m ( 99m Tc)-tetrofosmin myocardial single photon emission computed tomography (SPECT) performed at rest. Twenty-five patients underwent myocardial SPECT 3 weeks after the onset of acute myocardial infarction. Myocardial images were acquired at 40 min (early) and 4 h (delayed) after the injection of 740 MBq of 99m Tc-tetrofosmin. The regional myocardial uptake of the tracer in 26 segments of the left ventricular (LV) wall was visually scored from 0 (no activity) to 3 (normal activity), and then the RR was defined as a decrease of more than 1 point in the activity score on the delayed image compared with that on the early image. Regions with an activity score of...

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

“…However, in recent years, several studies have reported the presence of RRD in salvaged myocardium in at-risk areas in patients with AMI who underwent direct PCI [14][15][16][17][18][19][20][21]. Sugihara et al [14] reported that the frequency of observed RRD of 99m Tctetrofosmin was significantly higher in patients who underwent reperfusion therapy than in those who did not in the sub-acute phase of AMI.…”

“…Reverse redistribution (RRD) was observed between the initial and delayed images of AMI on myocardial perfusion images using a 99m Tc-labeled agent with almost no clearance in normal myocardium, which is reported to reflect mitochondrial damage in myocardium [14][15][16][17]. It has also been reported that RRD can predict functional recovery in the chronic phase.…”

“…However, these studies assessing myocardial uptake of 99m Tc-labeled agents were conducted using visual semi-quantitative analysis. Moreover, left ventricular function was assessed using left ventriculography (LVG) or echocardiography [14][15][16][17][18][19][20][21]. The findings of these studies on RRD were, therefore, not necessarily valid.…”

“…Several studies have investigated RRD in the sub-acute phase [14][15][16], though very few have investigated the relationship between RRD in the sub-acute phase and left ventricular functional recovery in the chronic phase [17].…”

Evaluation of Salvaged Myocardium After Acute Myocardial Infarction Using Single Photon Emission Computed Tomography After 201Tl-Glucose-Insulin Infusion

“…99m Tc-methoxyisobutyl isonitrile or 99m Tc-tetrofosmin is injected just before reperfusion therapy 32 and SPECT imaging is obtained after reperfusion. However, the myocardial perfusion by 201 Tl or 99m Tc imaging 33 underestimates the salvaged myocardium because myocardial perfusion is improved on follow-up perfusion imaging after 6 months.…”