Quantitative radionuclide assessment of regional ventricular function after thrombolytic therapy for acute myocardial infarction: results of phase I Thrombolysis in Myocardial Infarction (TIMI) trial

Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.

In Thrombolysis in Myocardial Infarction (TIMI) Phase I,290 patients with acute myocardial infarction were randomized to either intravenous recombinant tissue-type plasminogen activator (rt-PA) or intravenous streptokinase. Two hundred twenty-nine patients had radionuclide ventriculograms at discharge for assessment of global and regional left ventricular ejection fraction. Among these 229 patients 185 had totally occluded infarct-related arteries, and angiographic reperfusion of the infarct-related artery occurred in 69% of patients treated with rt-PA and 28% of patients treated with streptokinase (p less than 0.001). Mean global left ventricular ejection fraction was not different for rt-PA-treated patients compared with streptokinase-treated patients (0.46 versus 0.45). However, the average regional ejection fraction of the regions subtended by the infarct-related artery showed a trend toward better average infarct region ejection fraction in patients treated with rt-PA than in patients treated with streptokinase (0.40 versus 0.36; 0.05 less than p less than 0.06). Analysis of data according to perfusion status of the infarct-related artery showed no difference in mean global left ventricular ejection fraction between patients with sustained versus nonsustained reperfusion (0.47 versus 0.44). However, there was better average regional ejection fraction of the region subtended by the infarct-related artery in patients with sustained reperfusion (0.40 versus 0.36; p less than 0.01). Thus, quantitation of regional left ventricular function by radionuclide techniques provides a noninvasive means for evaluating the effects of thrombolysis. This study suggests a direct relation between improvement of regional left ventricular function and the greater infarct-related artery patency rate achieved by rt-PA compared with streptokinase.

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