Short-, mid-, and long-term reproducibility of the atrial signal-averaged electrocardiogram in healthy subjects: Comparison with the conventional ventricular signal-averaged electrocardiogram

Although atrial signal-averaged electrocardiogram (SAECG) has been proposed for noninvasive identification of patients with atrial tachyarrhythmias, the substantial variability of the measurement limits the clinical value. The aim of the study was to assess the short- to long-term reproducibility of atrial SAECG and to compare it to that of the conventional ventricular SAECG in 51 healthy volunteers (30 men; age 32 +/- 8 years). In each subject, SAECG recordings were obtained using MAC-VU electrocardiograph and HiRES and PHiRES software (Marquette Medical Systems) and repeated after 5 minutes, 1 day, 1 week, and 1 month. Automatically detected onset and offset of the filtered QRS complex and P wave were subsequently corrected by two independent observers, and the averaged values were used for the analysis. Conventional ventricular SAECG parameters: filtered QRS duration (QRS(tot)), low amplitude signal duration, and root mean square voltage (RMS) of the terminal 40 ms of QRS; and 5 atrial parameters: filtered P wave duration (P-tot), RMS of the terminal 40, 30, 20 ms, and of the entire P wave were obtained. Relative errors of different pairs of measures were used to assess the intrasubject reproducibility. QRS(tot) and P-tot were the most reproducible parameters. The relative errors after 5 minutes, 1 day, 1 week, and 1 month were 0.8% to 2.4% for QRS(tot), and 1.3% to 4.2% for P-tot. For RMS voltages, the relative errors exceeded 15% in short-term and 20% in long-term recordings. Although P-tot as statistically less reproducible than QRS(tot), the reproducibility of the former was good and comparable to that of the QRS(tot). The reproducibility of the voltage parameters was significantly poorer than that of the duration parameters. The study showed a satisfactory short- and long-term reproducibility of P-tot in the atrial SAECG in healthy subjects. However, low reproducibility of the Voltage parameters should be considered in clinical applications.