Accuracy in clinical arrhythmia detection of a real-time Holter system (Oxford Medilog 4500)

The accuracy of a real-time analysis Holter system (Oxford Medilog 4500) in detecting ventricular and supraventricular arrhythmias was evaluated. Hand-counted data from randomly selected hours of 152 ECG monitorings of 152 patients were used as the control standard. Accuracy of the system was evaluated on 606 hours for premature ventricular complexes (PVC), PVC couplets and supraventricular extrasystoles (SVE), and on 1,789 hours for ventricular tachycardia (VT), accelerated idioventricular rhythm (AIVR), and supraventricular tachycardia (SVT). Sensitivity and positive predictive accuracy for the Oxford system were (1) 92.9% and 94.9% for PVC; (2) 90.1% and 87.8% for PVC couplets; (3) 98.1% and 56% for AIVR; (4) 80% and 82.3% for VT; (5) 88.6% and 56.5% for SVE, and (6) 43.7% and 60.2% for SVT. Furthermore, negative predictive accuracy, the ability to predict the total absence of an arrhythmic event in an hour, was determined. It was 91.7% for PVC, 99.5% for PVC couplets, 99.9% for AIVR, 99.7% for VT, 95% for SVE, and 98% for SVT. Our results show good reliability of the Oxford system in the identification of ventricular arrhythmias, whereas significant inaccuracies appear to exist in the analysis of supraventricular arrhythmias.