Circadian Behavior of P‐Wave Duration, P‐Wave Area, and PR Interval in Healthy Subjects

Abstract

Background: The prolongation of P‐wave duration has long been shown to indicate the presence of high risk for atrial fibrillation. The circadian variation of P‐wave characteristics and their dynamic adaptation to heart rate changes was not tested before. Methods: To evaluate the diurnal pattern of P‐wave duration, P area, and PR interval and of their linearly fitted relation with RR interval, 50 healthy volunteers (25 men, mean age 34 ± 10 years) underwent 24‐hour ambulatory electrocardiographic (ECG) recording with digital 12‐lead Holter recorders. The median P‐wave duration, P area, and PR interval were calculated from the average 12‐lead ECG constructed from each 10‐second ECC recording. Single harmonic regression analysis was performed to reveal the presence of circadian variation in the aforementioned ECG parameters. Results: The P area (P < 0.0001, R²= 0.78), the PR interval (P < 0.0001, R²= 0.92), the P area / RR slope (P < 0.0001, R²= 0.55), and the PR/RR slope (P < 0.0001, R²= 0.42) showed a highly significant circadian variation while the periodic nature of P‐wave duration (P = 0.016, R²= 0.32) and of the P duration / RR slope (P = 0.011, R²= 0.18) was only indicated by harmonic regression analysis. Conclusions: P‐wave duration, P area, and PR interval show a significant circadian variation in healthy subjects. The relations between P area/RR,PR/ RR, and P duration/RR also demonstrate a significant diurnal pattern. A.N.E. 2001;6(2):92–97