Validity of P-peak to R-peak interval compared to classical PR-interval to assess dynamic beat-to-beat AV conduction variability on surface electrocardiogram

Abstract

Objective. Duration and dynamic changes of beat-by-beat PR intervals on surface electrocardiogram (ECG) requires accurate determination of QRS complex and P wave boundaries detection, which are influenced by signal-to-noise ratio and morphological variability. Atrioventricular duration (AVD), conventionally measured by PR-interval (ranging from P-onset to QRS-onset), requires adequate signal preprocessing and precise detection of fiducial points of ECG waves. This study aims at applying a method for dynamic beat-to-beat AVD variability measurement, based on the distance between P-wave and R-wave peaks (PR-peaks), and to validate the procedure in two different physical fitness status groups. Approach. The AVD interval was quantified by both conventional (PR-interval) and PR-peaks methods. Fiducial point detection was carried out in three different signal preprocessing conditions (low-pass filtering at 15 Hz, 25 Hz and 35 Hz). A comparative method was adopted to assess ventricular repolarization duration (VRD) measures (conventional QT-interval versus R-wave peak to T-wave interval) as reference of dynamic beat-by-beat variability. Eight male healthy sedentary and eight male elite runners, age, weight and height adjusted underwent 15 min resting ECG recording. Maximal VO2 consumption (VO2MAX) was also assessed defining physical fitness status. Main Results. For 15 Hz, 25 Hz and 35 Hz, the average correlation coefficient (r) values for PR-interval versus PR-peaks and QT-interval versus RT-interval were, respectively, 0.67, 0.59 and 0.50, and 0.76, 0.60 and 0.55. Additionally, for the same cutoff values, correlation coefficient between PSDs of intervals were, respectively, 0.87, 0.81 and 0.73; 0.99, 0.93 and 0.88. Bland Altman plots did not show inter methods differences across all cut-off frequencies. No-significant difference for AVD was observed for inter-group comparison, whereas, on the other hand, VRD was significantly larger in Athletes group. Significance. Assessment of PR-interval using either wave-onset or wave-peak approach as fiducial points provide accurate and precise results, and are appropriate to assess AVD physiological inter-beat interval variation.