Estimation of atrial fibrillatory frequency by spectral subtraction of wavelet denoised ECG in patients with atrial fibrillation

The objective of this study was to assess the efficacy of a novel wavelet based dominant atrial fibrillatory frequency (DAFF) estimation technique on twenty patients who underwent internal cardioversion at Royal Victoria Hospital, Belfast. The results acquired using the wavelet technique were compared against results achieved using a conventional average template subtraction (ATS) method with three performance parameters: percentage noise reduction ratio, ventricular activity (QRST) correlation value and percentage DAFF similarity ratio. The results for wavelet based estimation were 87.8%±5.3% and 0.983±0.006 respectively compared to 72.9%±9.3% and 0.981±0.010 for the ATS method. These results indicate that the wavelet technique offers improved performance at attenuating noise in the Q-T intervals than conventional technique, yet there remains high retention of the ventricular morphology, suggesting that the proposed wavelet technique could be a useful method for isolating atrial activity for DAFF analysis. DAFF estimated values using both techniques were compared and found to be in good agreement, as percentage DAFF similarity ratio was 94.8%±3.8%.