Real-time analysis ambulatory electrocardiography--clinical evaluation of cardiac arrhythmias by the Aegis system

To evaluate the technical reliability, clinical applicability, and arrhythmia accuracy of one manufacturer's real-time analysis ambulatory ECG instrument (Aegis Medical Systems), 164 patients were simultaneously examined through a "Y" cable by both a real-time analyzer and a conventional Holter recorder. Technical failure was similar for both recorders (2% in each), and the real-time analyzer was applicable to all patients encountered. Using a randomly selected hand-counted database of 799 hours as the standard of truth, accuracy of the real-time analyzer for hourly mean heart rate, isolated ventricular ectopic beats, ventricular couplets, ventricular tachycardia, isolated supraventricular ectopic beats and supraventricular tachycardia was determined. Mean heart rate showed 96% agreement and a high correlation (r = .986) to hand-counted values. Real-time analysis overall sensitivity, positive predictive accuracy, and false positive rate for the Aegis Medical System were (a) for isolated ventricular ectopic beats--92%, 92%, and 8%, (b) for ventricular couplets--80%, 97%, and 3%, (c) ventricular tachycardia--81%, 92%, and 8%, (d) supraventricular ectopic beats--81%, 82%, and 18%, and (e) for supraventricular tachycardia--75%, 89%, and 11%. Arrhythmia analysis was valid for mean heart rate and ventricular arrhythmias, but showed lower sensitivities in detection of low prevalence (1-60 b/Hr) ventricular couplets (72%) and ventricular tachycardia (43%). Significant inaccuracies for some densities of supraventricular arrhythmia were also found. This study found the real-time analysis ambulatory ECG similar to conventional Holter recording for technical reliability and patient applicability. Given the limitations of currently available real-time analysis ambulatory ECG systems, it is a promising technology.