Coronary artery reperfusion in acute myocardial infarction: Assessment by pre- and postintervention thallium-201 myocardial perfusion imaging

Abstract

In a randomized trial of intracoronary streptokinase (STK) therapy in acute myocardial infarction, 44 patients (21 control subjects and 23 patients treated with STK) underwent sequential thallium-201 planar imaging before angiography and after 4 hours (redistribution), 4 days and 6 weeks. Patients were classified according to the presence or absence of angiographic reperfusion of the infarct-related artery. The semiquantitative score of myocardial thallium uptake was expressed as percent of maximal defect score. Both in control and in STK-treated groups, thallium defect scores decreased over time, but this decrease was smaller in the control group (before angiography, 33 ± 4%; redistribution, 29 ±4%; 4 days, 25 ± 4%; and 6 weeks, 22 ± 4%) than in the STK group (44 ± 4%, 38 ± 4%, 26 ± 4% and 21 ± 3%, respectively). In patients in whom reperfusion was achieved (20 STK-treated, 6 control subjects), a marked decrease in thallium score was observed (before angiography, 40 ± 4%; redistribution, 32 ± 4%; 4 days, 20 ± 5%; and 6 weeks, 14 ± 22%) compared with patients in whom reperfusion was not achieved (37 ± 4%, 36 ± 5%, 33 ± 5% and 33 ± 4%, respectively). These results indicate that serial thallium imaging is an accurate method of assessing changes in myocardial perfusion after acute myocardial infarction. Restoration of thallium uptake was observed after reperfusion of the infarct-related artery whether this recanalization was seen spontaneously or after successful thrombolysis.