In the proposed research, investigators will extend conventional cardiac magnetic resonance methods to enable the creation of high-quality cine CMR images in the presence of multiple kinds of arrhythmia. Two arrhythmia-tolerant imaging methods will be adopted, which are particularly useful in arrhythmia: 1) 3D imaging, which is useful for many purposes, including "road mapping" of electrophysiology (EP) procedures, and 2) late gadolinium enhancement (LGE), which is useful for delineating abnormal myocardium, including fibrotic regions that can serve as sources of arrhythmias.