Planar myocardial scintigraphy with 99mTc sestamibi for the evaluation of the infarct area and the efficacy of the thrombolytic therapy]

BACKGROUND: Nuclear cardiology permits the estimation of myocardial infarction size and the result of the thrombolytic therapy. The aim of the study was to demonstrate the feasibility of the planar myocardial scintigraphy with tecnetium-99m-sestamibi in the coronary intensive care unit for the early identification of the infarct size and the results of the thrombolytic therapy. MATERIAL AND METHODS: We studied 15 patients affected by a first acute myocardial infarction (AMI), 10 anterior and 5 inferior wall, treated with thrombolysis (APSAC 30U i.v.) within and interval of 3 hours from the symptoms onset, tecnetium-99m-sestamibi was injected before thrombolysis and after 3 +/- 1 hours the planar imaging was registered with a mobile gamma-camera. Scintigraphic evaluation was repeated after 24 hours and before patient discharge. Within 48 hours from the thrombolytic therapy the coronary angiography was performed for the demonstration of patency of the infarct-related artery. The left ventricle myocardial perfusion was divided in the 3 planar projections into 13 segments. The perfusion in each segment was evaluated with a perfusion score: 0 = normal, 1 = moderately reduced, 2 = severely reduced, 3 = absent. The sum of the hypoperfused segments represented the infarct size. A perfusion score improvement greater than 40% was considered a marker of reperfusion. RESULTS: The infarct size involved 4.2 +/- 1.5 segments in the anterior and 2 +/- 0.8 segments in the inferior wall infarctions (p < 0.05). The scintigraphic imaging made 24 hours after AMI allowed the diagnosis of coronary reperfusion in 10 patients. The coronarography demonstrated the infarct related artery patency in 14 patients. The nuclear imaging at patient discharge provided the diagnosis or reperfusion in 11 cases and demonstrated an improvement of the myocardial perfusion score in 8 cases. CONCLUSIONS: In patients with AMI treated with thrombolysis the scintigraphic imaging with tecnetium-99m-sestamibi is feasible with a mobile gamma-camera in the intensive coronary care unit. The quality of planar imaging is good and allows the evaluation of myocardial infarct size and the efficiency of thrombolytic therapy. An earlier scintigraphic imaging should be taken into consideration for a more timely non-invasive evaluation of patients who need coronary angiography and, if necessary, a rescue-PTCA.