A computer implemented modelling method for identifying one or more ablation locations in an atrial tissue region in an atrial fibrillation patient with atrial fibrosis to target persistent AF rotors, the method comprising: receiving three-dimensional imaging data representing the atria of the patient, the three-dimensional imaging data comprising MRI data; generating a patient-specific model of the atria from the three-dimensional imaging data; conducting simulation of AF using the patient-specific atrial model to identify AF-perpetrating regions, wherein the AF-perpetrating regions comprise regions of tissue that contain organizing centers of persistent AF rotors during simulation; identifying from the AF-perpetrating regions one or more ablation locations in the atria, implementing ablation lesions in the patient-specific atrial model to target the regions of tissue which maintain the persistent AF rotors; and testing arrhythmia inducibility after the implementation of the ablation lesions until AF is no longer initiated following dynamic pacing, wherein said generating said patient-specific model of the atria from the three-dimensional imaging data further comprises constructing a geometric model of the atria, said geometric model including normal tissue regions and remodeled tissue regions determined for said patient using the three-dimensional imaging data, wherein said geometric model includes at least a geometric model of right and left atria of the patient's heart, wherein said remodeled tissue regions are segmented into a plurality of different regions based on said three-dimensional imaging data, said plurality of different regions including imaging data consistent with fibrotic regions, scar tissue regions, normal tissues regions, and transition zones between normal and fibrotic or scar tissue regions. receiving three-dimensional imaging data representing the atria of the patient, the three-dimensional imaging data comprising MRI data; generating a patient-specific model of the atria from the three-dimensional imaging data; conducting simulation of AF using the patient-specific atrial model to identify AF-perpetrating regions, wherein the AF-perpetrating regions comprise regions of tissue that contain organizing centers of persistent AF rotors during simulation; identifying from the AF-perpetrating regions one or more ablation locations in the atria, implementing ablation lesions in the patient-specific atrial model to target the regions of tissue which maintain the persistent AF rotors; and testing arrhythmia inducibility after the implementation of the ablation lesions until AF is no longer initiated following dynamic pacing, wherein said generating said patient-specific model of the atria from the three-dimensional imaging data further comprises constructing a geometric model of the atria, said geometric model including normal tissue regions and remodeled tissue regions determined for said patient using the three-dimensional imaging data, wherein said geometric model includes at least a geometric model of right and left atria of the patient's heart, wherein said remodeled tissue regions are segmented into a plurality of different regions based on said three-dimensional imaging data, said plurality of different regions including imaging data consistent with fibrotic regions, scar tissue regions, normal tissues regions, and transition zones between normal and fibrotic or scar tissue regions.