A method of targeting fibrosis or autonomic nerve tissue for ablation in a subject is provided. The method includes performing at least one EGM analysis of a plurality of recorded atrial EGMs for a tissue in a region suspected of having fibrosis or autonomic nerve tissue. With regard to targeting fibrosis for ablation, the method includes determining one or more correlations of at least one AF EGM characteristic to a region having fibrosis from the plurality of recorded atrial EGMs for the tissue and determining whether the tissue contains dense fibrosis that would preclude effective ablation of the analysis region of the tissue. With regard to targeting autonomic nerve for ablation, the method includes determining whether one or more significant changes in EGM characteristics with autonomic blockade exist that would indicate the need to perform ablation of the analysis region of the tissue.