| Abstract: | Background: Although prolonged duration of the signal‐averaged (SA) P wave has been proposed as a noninvasive marker of atrial arrhythmias, clinical value of atrial SAECG is limited, largely due to the difficulty with detection of the onset and offset of the high gain P wave. The aim of this study was to assess the reliability of automatic measurement of the atrial SAECG. Methods: Fifty‐one healthy volunteers (30 men; 32 ± 8 years) underwent a session of 3 atrial and 3 ventricular SAECG recordings. Automatically detected onset and offset of SA QRS complex (QRStot) and SA P wave (Ptot) were subsequently‐corrected by two independent observers. For ventricular SAECG, three conventional time‐domain parameters were calculated. For atrial SAECG, the following five parameters were measured: Ptot, root mean square voltages of the entire Ptot (RMS‐P) and of the terminal 40, 30, and 20 ms of Ptot. Relative errors of the different pairs of measurements were used to assess the interobserver and observer‐computer variability. The Bland‐Altman method was applied to express the agreement between measurements. Results: Although the mean interobserver relative errors were low for QRStot and Ptot (1.1% vs 1.5%), the observer‐computer error was significantly higher for Ptot than for QRStot (1.7% vs 7.1%; P < 0.0001). For the voltage parameters, the lowest interobserver and observer‐computer relative errors were found for RMS‐P (6.6% vs 7.3%, P = ns). For RMS voltages of the terminal 40–20 ms of Ptot, relative errors exceeded 10%, but the interobserver error was significantly lower than the observer‐computer error (P < 0.0001). Conclusion: Automatic detection of the SA P‐wave onset and offset is unreliable and the atrial SAECG requires manual correction. Given a good interobserver agreement, such a correction is unlikely to introduce any significant observer‐dependent bias. A.N.E. 2000; 5(2):133–138 |
