A computer-implemented method for localizing an activation site of origin to a segment of the heart comprising: obtaining a body-surface potential map (BSPM) of interest based on a plurality of simultaneously recorded electrocardiographic signals from a plurality of leads; calculating an integral of the signal recorded from each of a subset of the plurality of leads and identifying a condition of the integral as positive or negative for each of the subset of the plurality of leads; comparing the condition of each of the subset of the plurality of leads with the condition of the subset of the plurality of leads used for each of pre-determined set of BSPM templates, the set comprising one BSPM template for each pre-defined segment of the heart, to identify a selected set of BSPM templates having matching conditions; comparing a body surface potential map (BSPM) of interest to each BSPM template of the selected set of BSPM templates, wherein comparing comprises, for each BSPM template of the set of BSPM templates: retrieving a BSPM template from memory from the selected set of BSPM templates; and calculating one or more comparison metrics for the BSPM template retrieved as compared to the body surface potential map (BSPM) of interest, wherein each of the BSPM templates was generated by averaging BSPMs of all pacing sites within the associated segment of the heart from a collection of BSPMs stored in memory; identifying the BSPM template that most closely resembles the body surface potential map (BSPM) of interest using the one or more comparison metrics calculated in order to identify the segment of the heart in which the activation site of origin is likely to be located. obtaining a body-surface potential map (BSPM) of interest based on a plurality of simultaneously recorded electrocardiographic signals from a plurality of leads; calculating an integral of the signal recorded from each of a subset of the plurality of leads and identifying a condition of the integral as positive or negative for each of the subset of the plurality of leads; comparing the condition of each of the subset of the plurality of leads with the condition of the subset of the plurality of leads used for each of pre-determined set of BSPM templates, the set comprising one BSPM template for each pre-defined segment of the heart, to identify a selected set of BSPM templates having matching conditions; comparing a body surface potential map (BSPM) of interest to each BSPM template of the selected set of BSPM templates, wherein comparing comprises, for each BSPM template of the set of BSPM templates: retrieving a BSPM template from memory from the selected set of BSPM templates; and calculating one or more comparison metrics for the BSPM template retrieved as compared to the body surface potential map (BSPM) of interest, wherein each of the BSPM templates was generated by averaging BSPMs of all pacing sites within the associated segment of the heart from a collection of BSPMs stored in memory; retrieving a BSPM template from memory from the selected set of BSPM templates; and calculating one or more comparison metrics for the BSPM template retrieved as compared to the body surface potential map (BSPM) of interest, wherein each of the BSPM templates was generated by averaging BSPMs of all pacing sites within the associated segment of the heart from a collection of BSPMs stored in memory; identifying the BSPM template that most closely resembles the body surface potential map (BSPM) of interest using the one or more comparison metrics calculated in order to identify the segment of the heart in which the activation site of origin is likely to be located.