Prognostic significance of the evolution of left ventricular ejection fraction in patients with acute myocardial infarction not treated with thrombolytic therapy

Several controlled trials on the thrombolytic treatment of acute myocardial infarction (AMI) have failed to demonstrate that thrombolysis has a simultaneous positive effect on left ventricular function and survival. One explanation may be that spontaneous changes in left ventricular function occurred during the progression of AMI in control patients. The aim of this study was to evaluate the spontaneous evolution of left ventricular ejection fraction (LVEF) and its prognostic influence on early (1 month) and late (1 year) mortality in patients with AMI. We studied 216 patients admitted to our CCU within 24 h of the onset of symptoms. LVEF was determined by radionuclide ventriculography on admission (RNV1) and at the end of the necrotic phase (RNV2). Fourteen patients died before RNV2. On the basis of LVEF values at RNV1, the remaining 202 patients were divided into two groups: those with a normal LVEF (≥55%), and those with an abnormal LVEF (<55%). Among patients with a normal LVEF at RNV1 (64 patients) a significant increase (>12%) in LVEF at RNV2 was observed in 12.5%, a significant decrease (>12%) in 12.5% and no change at all in 75%. All of these patients survived, regardless of the evolution of LVEF. In patients with an abnormal LVEF at RNV1 (138) a significant increase (>5%) in LVEF at RNV2 was observed in 72.5%, a significant decrease (>5%) in 6.5% and no change at all in 21%. In patients with a LVEF increase, both early and late mortality were significantly lower than in patients with a LVEF decrease: (early mortality 4% vs 55.5%, P <0.001; late mortality 6% vs 66.6%, P <0.001) respectively. In patients without any LVEF change, mortality was significantly lower than in patients with a LVEF decrease: (early mortality 10% vs 55.5%, P = 0.01; late mortality 14% vs 66.6%, P =0.004) respectively. In conclusion, our data demonstrate that a significant increase in LVEF occurs in most patients with an early depression of left ventricular function. This behaviour is associated with a low early and late mortality in comparison with the patients with a LVEF decrease and is independent of thrombolytic treatment. When the early measurement of LVEF is normal the prognosis is not influenced by LVEF evolution. These findings must be kept in mind when LVEF is used as a prognostic index and as an end-point for the evaluation of the effects of thrombolytic therapy.