Since the emergence of atrial fibrillation (AF) ablation as a reliable method of restoring sinus rhythm, various approaches have been used to improve the efficacy while maximizing the safety of ablation. A major hurdle to optimizing outcomes for AF ablation has been the failure to recognize that the substrate of the individual patient plays a significant role in optimizing AF treatment. Using delayed-enhancement MRI for the detection of left atrial fibrosis, our group has been able to correlate these structural remodeling changes to outcomes of stroke, AF recurrence and congestive heart failure. This has provided us with information to optimize care of our AF patients based on screening for a fibrotic atrial cardiomyopathy, for which AF is the arrhythmic manifestation. By employing an MRI-guided approach for AF ablation, we have been able to optimize AF management and enhance the delivery of personalized medicine for our patients.