Systolic left ventricular function after reperfusion therapy for acute myocardial infarction. Analysis of determinants of improvement. The TAMI Study Group.

BACKGROUND Contrast ventriculograms of 542 patients treated with intravenous thrombolytic agents for acute myocardial infarction were examined to define changes in left ventricular ejection fraction and regional wall motion that occur during the first week after reperfusion therapy for acute myocardial infarction and define clinical, acute angiographic and treatment variables related to improvement in global and regional left ventricular function. METHODS AND RESULTS Intravenous tissue-type plasminogen activator and/or urokinase was administered to 805 patients during acute myocardial infarction. Mean time from symptom onset to thrombolytic therapy was 3 hours (22 patients received therapy within the first hour). Acute and 7-day catheterization were performed. Paired left ventricular ejection fraction and centerline regional wall motion were available in 542 patients (67%). Stepwise, multivariable analysis of clinical, acute angiographic and treatment variables was used to develop two models: One related to improvement in left ventricular ejection fraction, and the second related to improvement in infarct zone regional function. Left ventricular ejection fraction did not change (51.2 +/- 11.1% for acute versus 51.9 +/- 11.0% for 1 week, p = 0.19). Improvement in infarct zone regional function was modest (14%) at 1 week (-2.54 +/- 1.07 standard deviation per chord for acute versus -2.17 +/- 1.24 at 1 week, p < 0.001). Subgroup analysis demonstrated modest improvement in ejection fraction (1.4 +/- 9.5%) and greater improvement in infarct zone function (19%) in patients with successful sustained reperfusion at 1 week. Depressed left ventricular ejection fraction and infarct zone regional wall motion at the acute study were strongly associated with improvement of these parameters at 1 week. Resolution of chest pain before acute catheterization, infarct-related artery flow at acute catheterization, and depressed regional wall motion in the noninfarct zone were associated with improvement in both ejection fraction and regional infarct zone function at 1 week. Notably, the time from the onset of symptoms to initiation of thrombolytic treatment was not related to subsequent improvement in ventricular function. CONCLUSIONS Dramatic improvement in left ventricular systolic function is not common after thrombolytic therapy for acute myocardial infarction. Improvement in global and regional systolic function is most closely related to acutely depressed ventricular function and successful acute coronary recanalization. Thus, patients with the most myocardium in jeopardy and successful coronary reperfusion demonstrate the greatest improvement in global and infarct zone ventricular function. Overall, the magnitude of this improvement is modest, suggesting that the benefits of coronary reperfusion are not solely related to improvement in systolic left ventricular function.