Separating the atrial and ventricular components in atrial fibrillation. Are 64 leads better than 12?

It is important to be able to separate the atrial activity from the dominant ventricular activity of the body surface ECG signals in atrial fibrillation so that the effect of therapies such as drug cardioversion and ablation can be adequately assessed. Principal Component Analysis (PCA) and Independent Component Analysis (ICA) are algorithms which can be used but their application has been limited to standard 12-lead ECG recordings. Our aim was to investigate whether better separation of the atrial and ventricular activities could be achieved using additional leads. We applied PCA and ICA to ECG recordings of 12 and 64 leads in 5 patients in atrial fibrillation. We measured and compared between the 12 lead and 64 lead analyses the amplitude of residual ventricular QRS which remained in the separated atrial activity and the dominant fibrillatory frequency. We found that there was little difference between 12 and 64 leads in separating the atrial and ventricular activity.