Methods and systems for determining optimal spatial resolution for mapping cardiac fibrillation in a patient, including obtaining one or more electrograms, having an initial spatial resolution； calculating at least one electrogram frequency； obtaining one or more electrograms, having a higher spatial resolution； calculating at least one electrogram frequency, having a higher spatial resolution； comparing at least one electrogram frequency having a higher spatial resolution with at least one electrogram frequency having an initial spatial resolution； iterating the steps above until the electrogram frequencies of the two compared electrograms are the same； and identifying at least one of minimum spatial resolution threshold and an optimal spatial resolution based on the step of comparing.
