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

Reverse redistribution (RR) of Tc-99m-sestamibi is observed after direct pe rcutaneous transluminal coronary angioplasty (PTCA) in acute myocardial inf arction (AMI). The purpose of this study was to clarify the functional char acteristics of myocardial segments with RR after direct PTCA in AML Thirty patients with AMI who had undergone direct PTCA were examined. Myocardial p erfusion tomography with Tc-99m-sestamibi and low dose dobutamine echocardi ography were performed within 2 weeks of the onset. The Tc-99m-sestamibi im ages were obtained 1 and 3 h after tracer administration. The left ventricl e was divided into nine segments, and regional Tc-99m-sestamibi uptake and clearance were quantitatively evaluated in each segment. RR was defined as a decrease in Tc-99m-sestamibi uptake of > 10% on 3 h delayed images compar ed with the 1 h early images. The left ventricle in the echocardiographic i mages was also divided into nine segments corresponding to the scintigraphi c images, and regional wall motion was assessed in the resting condition as the baseline and during dobutamine administration (5-10 mug.kg(-1).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 myocar dium. Enhanced clearance of Tc-99m-sestamibi was observed in ischaemic segm ents with RR (P < 0.001). Echocardiography demonstrated that 24 out of 25 s egments with RR and 61 out of 86 segments without RR had wall motion abnorm alities. Dobutamine infusion improved wall motion in 20 (83%) of the 24 dys functional segments with RR and 33 (54%) of the 61 dysfunctional segments w ithout RR (P < 0.02). These findings suggest that RR indicates reversible f unctional abnormalities associated with preserved contractile reserve in re sponse to dobutamine. The early and delayed imaging of Tc-99m-sestamibi pro vides useful information regarding the residual viability of the dysfunctio nal myocardium in AMI patients. ((C) 2001 Lippincott Williams & Wilkins).