Use of left ventricular function as an end point of thrombolytic therapy.

In recent acute myocardial infarction, early reperfusion of the infarct-related artery by intracoronary or intravenous thrombolytic therapy induces a significant limitation of infarct size, provided reperfusion occurs within a time frame that myocardial salvage can still be expected. Limitation of infarct size reduces scar tissue formation, aneurysm formation, infarct zone expansion, left ventricular volume enlargement, and eventually results in higher left ventricular ejection fraction. Infarct size limitation and left ventricular function preservation occur with all thrombolytic agents currently in clinical use: streptokinase, alteplase and, more recently, anistreplase. When anistreplase is compared with conventional heparin therapy, a 31% reduction in infarct size is found (estimated from single photon emission computed tomography, or SPECT). This translates into a significant preservation of left ventricular ejection fraction as observed in anistreplase-treated patients compared with heparin-treated patients (0.53 +/- 0.13 vs 0.47 +/- 0.12, p less than 0.002). In comparative trials of 2 thrombolytic agents, anistreplase was demonstrated to be as efficient as alteplase on left ventricular ejection fraction preservation and infarct size limitation.