In 378 placebo patients enrolled in the European Infarction Study (EIS), a secondary prevention study after acute myocardial infarction, 24-h baseline Holter monitoring was done 14 to 31 days after MI, and the relationship of electrical (ventricular arrhythmias) and mechanical (clinical signs of ventricular dysfunction) risk factors was analysed on the basis of mortality during the subsequent 2 years of follow-up. There was a rather low overall 2-year mortality rate of 6.9%. Consecutive arrhythmias (ventricular pairs and runs of ventricular premature beats) and left-ventricular dysfunction alone were associated with a low mortality of 4.0% and 3.6%, respectively. However, the combination of both defined a high-risk group characterized by a 2-year mortality rate of 16.7%. Additionally, the risk of dying was dependent on the frequency of consecutive arrhythmias: 22.2% of the patients with greater than 10 ventricular pairs per day died during the follow-up period in contrast to 9.9% of those with only 1-10 ventricular pairs per day. Thus, only the combination of electrical and mechanical risk factors, and especially the frequency of consecutive VPB, is helpful in identifying a subgroup of postMI patients with poor clinical outcome. An intervention study should restrict itself to this risk population only.