Relationship between resting 201Tl reverse redistribution, microvascular perfusion, and functional recovery in acute myocardial infarction.

201TI reverse redistribution is a common finding early after reperfusion therapy for myocardial infarction. Its mechanism and clinical implications remain unclear. The aim of this study was to clarify the relationships between reverse redistribution, microvascular perfusion, and myocardial viability. METHODS: Resting, 10-min-postinjection, and redistribution 201TI data obtained for 33 patients 8 and 42 d after the onset of acute myocardial infarction were compared with echocardiographic wall motion measured acutely and on day 42. Microvascular perfusion was assessed by myocardial contrast echocardiography performed 10 min after restoration of complete patency of the infarct artery. RESULTS: Marked significant reverse redistribution was found on day 8 (absolute change, 7.5%+/-7.9% of the 10-min-postinjection defect size; P<5x0.000001) and significantly decreased on day 42 (2.7%+/-6.8%; P = 0.004 between days 8 and 42). The 10-min-postinjection defect size best predicted the final infarct size on day 42 and was closely related to microvascular perfusion. Patients with adequate reperfusion had a smaller postinjection defect on day 8 (21.1%+/-14.6%) and a larger reverse redistribution (10.2%+/-6.1%) than did patients with no reflow (35.3%+/-13% and 3.2%+/-9.2%, respectively; P<0.04 for both). CONCLUSION: Reverse redistribution was marked early after myocardial infarction in patients with complete patency of the infarct artery and decreased in subsequent weeks. Reverse redistribution was associated with restoration of adequate microvascular reperfusion and with myocardial salvage and viability. The early postinjection scans on day 8 were the relevant images for assessing myocardial salvage and predicting wall motion recovery.