Evaluation of arrhythmias in the late hospital phase of acute myocardial infarction compared to coronary care unit ectopy.

To evaluate the prevalence and nature of arrhythmias during the entire three-week period in hospital after myocardial infarction, the results of coronary care unit monitoring (initial 3 to 5 days) were compared with continuous 8-hour portable monitoring during the ambulatory phase (second and third weeks) in 83 consecutive survivors. Arrhythmias were detected in 84.3 per cent (70/83) of patients while in the coronary care unit and in 85.5 per cent (71/83) during hospital stay after the coronary care unit. Ventricular ectopic depolarizations were classified as complicated (multifocal, paired, R on T, or five or more a minute) or uncomplicated. Importantly, the high frequency of complicated ventricular extrasystoles and tachycardia persisted during the entire period in hospital (early 34.9% and late 42.5% of all patients). However, only 16.9 per cent (14/83)had these ventricular arrhythmias during both coronary care unit and ward monitoring. Thus, the absence of complicated ventricular ectopic depolarization and ventricular tachycardia in the coronary care unit did not exclude their subsequent occurrence in the majority of the large number of patients with late hospital complicated ventricular ectopy.