The effect of QRS cancellation on atrial fibrillatory wave signal characteristics in the surface electrocardiogram

QRS cancellation methods have been used to analyze atrial activity in the electrocardiogram for such rhythms as atrioventricular dissociated ventricular tachycardia and atrial fibrillation. However, how well the cancellation methods work has never been evaluated by some gold standard. In this study of patients undergoing radiofrequency ablation of the atrioventricular junction, the contribution of imperfect cancellation was evaluated by comparing the "pure" atrial fibrillation (the gold standard) during a brief ventricular asystole to data obtained by a cancellation method during pacing just before and after the asystole. The results were compared by linear regression. The peak frequencies were 4.8-7.3 (6.1 ± 0.8) Hz for the "pure" and 4.8-6.8 (5.9 ± 0.7) Hz for the cancelled electrocardiogram segments (R² = 0.89) (similar results for median frequency), and the mean short-time Fourier transform peak frequencies were 4.6-7.1 (5.9 ± 0.8) Hz for the "pure" and 4.7-6.8 (5.9 ± 0.7) Hz for the cancelled segments (R² = 0.96). Further comparison was accomplished using synthesized signals. Based on our study, the cancellation method is reliable for studying atrial fibrillatory wave characteristics. As reported previously, the peak frequency and most power for atrial fibrillation in humans are in the 4-9 Hz band.