The influence of QRS cancellation on signal characteristics of atrial fibrillation in the surface electrocardiogram

QRS cancellation methods have been used to analyze atrial activity in the ECG including atrial fibrillation. In this study, the contribution of imperfect cancellation was evaluated by comparing "pure" atrial fibrillation in a brief ventricular asystole after RF ablation of the AV junction, and data obtained by the cancellation method during pacing just before and after. The results were compared by linear regression. The peak frequencies were 4.8-7.3 (5.5±0.8) Hz for the "pure" and 4.8-6.7 (5.4±0.7) Hz for the cancelled ECG segments (R²=0.89), and the mean STFT peak frequencies were 4.6-6.9 (5.8±0.7) Hz for the "pure" and 4.8-6.8 (5.8±0.7) Hz for the cancelled segments (R²=0.97). Thus, cancellation is reliable for characterizing atrial fibrillation. The peak frequency and maximum power for atrial fibrillation are in the 4-9 Hz band as reported previously.