A computer implemented method for analyzing an atrial electrogram signal, the computer implemented method comprising: analyzing both positive and negative deflections of the atrial electrogram signal over an analysis time period of said signal; and determining at least one characteristic of the atrial electrogram signal based at least in part on analyzing both positive and negative deflections of said signal over said analysis time period; wherein the step of analyzing both positive and negative deflections of the atrial electrogram signal comprising determining the time location of at least one cardiac activation within the analysis time period based at least in part on analyzing both positive and negative deflections over said analysis time period; characterised in that the step of determining the time location of at least one cardiac activation comprises subjecting the atrial electrogram signal to a processing step in which the first derivative and the second derivative is determined for the atrial electrogram signal over the analysis time period, and determining the time location of each cardiac activation at least in part as a function of a local minima or maxima of at least one of the first derivative and the second derivative of the atrial electrogram signal, and the step of determining the time location of at least one cardiac activation comprises, subsequent to the processing step, further subjecting the atrial electrogram to a triggering step in which activation location marker candidates are determined, the triggering step comprising determining the absolute value of the second derivative of the atrial electrogram signal over the analysis time period of the signal, and comparing the second derivative to a predetermined threshold wherein each time location at which the absolute value of the second derivative of the signal is greater than the predetermined threshold is considered as an activation location marker candidate. analyzing both positive and negative deflections of the atrial electrogram signal over an analysis time period of said signal; and determining at least one characteristic of the atrial electrogram signal based at least in part on analyzing both positive and negative deflections of said signal over said analysis time period; wherein the step of analyzing both positive and negative deflections of the atrial electrogram signal comprising determining the time location of at least one cardiac activation within the analysis time period based at least in part on analyzing both positive and negative deflections over said analysis time period; characterised in that the step of determining the time location of at least one cardiac activation comprises subjecting the atrial electrogram signal to a processing step in which the first derivative and the second derivative is determined for the atrial electrogram signal over the analysis time period, and determining the time location of each cardiac activation at least in part as a function of a local minima or maxima of at least one of the first derivative and the second derivative of the atrial electrogram signal, and the step of determining the time location of at least one cardiac activation comprises, subsequent to the processing step, further subjecting the atrial electrogram to a triggering step in which activation location marker candidates are determined, the triggering step comprising determining the absolute value of the second derivative of the atrial electrogram signal over the analysis time period of the signal, and comparing the second derivative to a predetermined threshold wherein each time location at which the absolute value of the second derivative of the signal is greater than the predetermined threshold is considered as an activation location marker candidate.