Continuous electrocardiographic monitoring for more than one hour does not improve the prognostic value of ventricular arrhythmias in survivors of first acute myocardial infarction.

This study was designed to compare the prognostic value of predischarge ambulatory electrocardiographic monitoring for 1, 6 and 24 hours in 188 patients surviving a first acute myocardial infarction. Ventricular premature complexes (VPCs) were considered as a mean hourly rate or classified using Lown and Moss grading systems. During the 1-year follow-up 20 cardiac deaths occurred. For all 3 monitoring times, a higher number of VPCs/hour and a higher Moss grade were associated with mortality, whereas a Lown grading system gave prognostic information only for the first hour of recording. Monitoring time did not influence specificity or sensitivity in predicting mortality; > or = 3 VPCs/hour showed a higher sensitivity than > or = 10 VPCs/hour (p < 0.05) with a comparable specificity. After 1-hour data entered the model, neither the 6- or the 24-hour data entry improved the overall likelihood ratio statistic, regardless of what VPC grading system was used. These results demonstrate that continuous electrocardiographic recordings of > 1 hour are unnecessary when they are to be used for detecting ventricular arrhythmia as a predictor of mortality in patients surviving a first acute myocardial infarction.