The 12-lead standard electrocardiogram (ECG) is a 10 second recording of human myocytes electrical activity. Filters and oversampling are necessary in order to acquire a smooth signal without distortion. ECG recordings may display ongoing arrhythmias, and some leads may be helpful in formulating the diagnosis. Advanced modalities of baseline ECG recording can be used to extract additional information with significant prognostic value. Ambulatory ECG (AECG) recording is a long-term and low-cost external recording obtained with 1 to 12 leads lasting from 24 to 30 days. For patient comfort, longer AECG recordings use fewer leads.