Reverse redistribution of 99mTc-sestamibi after direct percutaneous transluminal coronary angioplasty in acute myocardial infarction: relationship with wall motion and functional response to dobutamine stimulation

Abstract

Reverse redistribution (RR) of 99mTc-sestamibi is observed after direct percutaneous transluminal coronary angioplasty (PTCA) in acute myocardial infarction (AMI). The purpose of this study was to clarify the functional characteristics of myocardial segments with RR after direct PTCA in AMI. Thirty patients with AMI who had undergone direct PTCA were examined. Myocardial perfusion tomography with 99mTc-sestamibi and low dose dobutamine echocardiography were performed within 2 weeks of the onset. The 99mTc-sestamibi images were obtained 1 and 3 h after tracer administration. The left ventricle was divided into nine segments, and regional 99mTc-sestamibi uptake and clearance were quantitatively evaluated in each segment. RR was defined as a decrease in 99mTc-sestamibi uptake of >10% on 3 h delayed images compared with the 1 h early images. The left ventricle in the echocardiographic images was also divided into nine segments corresponding to the scintigraphic images, and regional wall motion was assessed in the resting condition as the baseline and during dobutamine administration (5-10 microg x kg(-1) x min(-1)). Out of a total of 270 myocardial segments, 111 segments were perfused by the culprit coronary artery and were defined as ischaemic segments. There were 25 segments with RR and 86 segments without RR in the ischaemic myocardium. Enhanced clearance of 99mTc-sestamibi was observed in ischaemic segments with RR (P<0.001). Echocardiography demonstrated that 24 out of 25 segments with RR and 61 out of 86 segments without RR had wall motion abnormalities. Dobutamine infusion improved wall motion in 20 (83%) of the 24 dysfunctional segments with RR and 33 (54%) of the 61 dysfunctional segments without RR (P<0.02). These findings suggest that RR indicates reversible functional abnormalities associated with preserved contractile reserve in response to dobutamine. The early and delayed imaging of 99mTc-sestamibi provides useful information regarding the residual viability of the dysfunctional myocardium in AMI patients.

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].…”

Myocardial washout of 99mTc-tetrofosmin and response to steroid therapy in patients with cardiac sarcoidosis

“…Therefore, 99m Tc-labeled agents are widely used as myocardial perfusion tracers [17][18][19][20][21][22]. However, washout phenomenon (WO) of the 99m Tclabeled agents from early imaging to delayed imaging has been reported observed in various diseases such as acute myocardial infarction (AMI), complete left bundle branch block, and hypertrophic cardiomyopathy (HCM) [23][24][25][26][27][28].…”