Ratio of ST-Segment and myoglobin slopes to estimate myocardial salvage during thrombolytic therapy for acute myocardial infarction

The use of intravenous thrombolytic therapy to achieve myocardial salvage has become common practice in patients presenting during the early hours of acute myocardial infarction (AMI).^1-3 A prompt, noninvasive estimation of salvage would be useful in determining further therapy for each patient. Clinical indexes of salvage should be accurate, easy to perform, inexpensive, and yield rapid results. Standard electrocardiographic and serum biochemical methods have been shown to indicate myocardial reperfusion.^4-9 Electrocardiographic ST-segment elevation tends to partially resolve immediately after reperfusion, but only 50% of patients have as much as 50% resolution within 90 minutes.⁴ Plasma levels of intracellular macromolecules increase early owing to washout through the lymph and blood, but only if irreversible damage has already occurred.^5-9 The present study of patients with AMI was designed to observe serial changes in both the ST segments, and serum levels of creatine kinase-MB and myoglobin after angiographically documented reperfusion; it tests the hypothesis that the ratio of ST-segment decrease to serum macromolecular increase can predict salvage of the jeopardized myocardium.