A study of 585 patients with acute myocardial infarction (285 with and 300 without cardiac arrest) showed the two groups to differ significantly in terms of clinical, laboratory and electrocardiographic findings. Resuscitation effectiveness depended upon the form of cardiac arrest (chi 2 = 209.25; p less than 0.001). A stable resuscitation effect (survival within and beyond 28 days after the onset of acute myocardial infarction) was achieved in 78.4% of cases of primary ventricular fibrillation, 24.0% of cases of secondary ventricular fibrillation, and 4.9% of asystolia cases. All cases of electromechanical dissociation were fatal. Long-term follow-up showed that 17.3% of patients with cardiac arrest and 21.9% of patients without cardiac arrest died over 4 years (p greater than 0.05).