A method for annotating ECG signals with a time of activation of a myocardium is provided which comprises receiving a bipolar signal and one unipolar signal of the bipolar signal from a pair of electrodes, computing a local unipolar minimum derivative of the unipolar signal at a plurality of times of occurrences of the local unipolar minimum derivative, computing a bipolar derivative of the bipolar signal, evaluating a ratio of the bipolar derivative to the local unipolar minimum derivative, annotating each time of occurrence as a time of activation of the myocardium at a location in a heart when the ratio is greater than a threshold value, extracting features of the annotations and assigning a confidence level to each feature, eliminating annotations based on a subset of the extracted features and a pair reduction analysis, and generating a local activation time map using the remaining candidate annotations.