Intravenous rt-PA achieved a higher 90-minute reperfusion rate than streptokinase (62% vs 31%, p<0.001), though ejection fraction only increased in patients achieving early reperfusion.
Does intravenous rt-PA improve left ventricular function compared to streptokinase in patients with acute myocardial infarction?
In acute myocardial infarction, early reperfusion with thrombolytic therapy improves regional wall motion, but overall ejection fraction does not significantly change by discharge regardless of whether rt-PA or streptokinase is used.
In Phase I of the NHLBI trial of Thrombolysis in Myocardial Infarction (TIMI), 290 patients admitted within 7 hr after onset of acute infarction were randomly assigned to intravenous treatment with either streptokinase (SK) or recombinant tissue-type plasminogen activator (rt-PA). Left ventricular function was measured from contrast ventriculograms in 145 patients with both pretreatment and predischarge studies analyzable. Regional wall motion in the infarct site was measured by the centerline method and expressed in units of standard deviations (SDs) from the mean motion in 52 normal subjects. Patients treated with rt-PA (n = 77) achieved a significantly higher reperfusion rate after 90 min of treatment. Perfusion of the infarct-related artery improved from visual grade 0 or 1 (total occlusion or penetration without perfusion) to grade 2 or 3 (partial or full reperfusion) in 62% receiving rt-PA vs 31% receiving SK (n = 68) (p less than .001). However, the ejection fraction did not change significantly from before treatment to before discharge in either treatment group (+0.7 +/- 6.7% vs +1.0 +/- 8.3%, respectively). A small but significant increase in regional wall motion was observed in each of the two groups (+0.4 +/- 0.8 vs +0.3 +/- 0.8 SD/chord, respectively; each p less than .001 compared with baseline). This was countered by declines in the hyperkinesis of the noninfarct region (-0.3 +/- 1.0 SD/chord p = .01 compared with baseline and -0.2 +/- 1.0 SD/chord p = .23, respectively). Analysis of the combined groups revealed that the ejection fraction increased only in patients who achieved reperfusion by 90 min after onset of therapy or who had subtotal occlusions initially. There was greater recovery of left ventricular function in patients who achieved reperfusion earlier vs later than 4 hr after symptom onset and in patients with vs without some collateral circulation to the infarct-related artery.
Sheehan et al. (1987) studied this question. Intravenous rt-PA achieved a higher 90-minute reperfusion rate than streptokinase (62% vs 31%, p<0.001), though ejection fraction only increased in patients achieving early reperfusion.
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