Importance of effective, early and sustained reperfusion during acute myocardial infarction

Abstract

The determinants of myocardial salvage after thrombolytic therapy during acute myocardial infarction (AMI) have not been clearly defined. In 1984, a prospective randomized trial was undertaken to define the relations between delay to treatment and effectiveness of perfusion to salvage of myocardium. Patients presenting within 2 hours of symptom onset received intravenous streptokinase immediately (group 1, 20 patients) or 5 hours after symptom onset (group 2, 16 patients). Effective perfusion (≤90% residual stenosis with rapid distal runoff) occurred in 63% of patients in both groups. Five patients, all in group 1, had recurrent AMI; 4 of the 5 had effective perfusion. There was no group difference in left ventricular ejection fraction at baseline or before discharge. However, group 1 patients with effective perfusion tended to have a greater predischarge mean ejection fraction than those in group 1 with ineffective perfusion (53 ± 13 vs 44 ± 16%, p < 0.10) and had a greater mean value than those in group 2 with ineffective perfusion (53 ± 13 vs 38 ± 17%, p < 0.03). The ejection fraction did not change significantly between admission and discharge in either group, but it increased significantly in group 1 patients with effective perfusion and no recurrent AMI (ΔEF = +6 ± 8%, p < 0.04). Group 1 patients with ineffective perfusion had a significant decrease in ejection fraction (ΔEF = −4 ± 4%, p < 0.04). In group 2 patients the ejection fraction did not change, regardless of the state of perfusion. This study highlights the independent importance of both early therapy and effective reperfusion to achieve myocardial salvage, and the high risk for reinfarction in such patients.