Effect of electrocardiographic recording duration on ventricular dysrhythmia detection after myocardial infection.

Abstract

To determine the effect of varying the duration of ECG recording on the detection of high premature ventricular complex (PVC) rates (30 or more PVC/h) and/or complex PVC (multiform PVC, couplets or runs) in survivors of myocardial infarction 175 ECG tapes (24 h) with such arrhythmias were evaluated for their occurrences detected in the first 1, 2, 6, 12 and 18 h of the recordings. The 1st hour of recording disclosed 47% of the tapes that, over 24 h, showed high PVC rates or complex PVCs or both; 6 h of recording uncovered 89% of the tapes with these arrhythmias. Although a 12 h ECG recording uncovered only 84% of the tapes with couplets and 75% of those with runs, it identified 92% of the tapes with high PVC rates and/or complex PVC. The detection rate of high PVC rates or complex PVC is logarithmically related to the recording duration. Tapes that had complex PVC and peak PVC rates > 100 beats/hour (78%) and 63% of the tapes with these complex PVC and peak PVC rates of 30-100 beats/h showed these complex PVC in the 1st hour. Only 22% of the tapes with complex PVC and peak PVC rates < 30 beats/h were identified during the same interval. The average number of PVC/h was slightly higher in the 1st than the last 12 h of the tapes (51 vs. 43 PVC/h). The detection rate for complex PVC during the 1st h of recording is related to the peak PVC rate. A 12 h recording during the waking period is sufficient to identify most survivors of myocardial infarction who have high PVC rates and/or complex PVC. The detection of tapes with high PVC rates or complex PVC can be predicted from its logarithmic relationship with the recording duration.