We are performing a study of 40 patients with current accepted indications for CRT and no MRI contraindications. These patients will have a pre-CRT MRI and another post-CRT MRI 6 months after the CRT procedure. Echocardiography, cardiopulmonary exercise testing, symptom assessment, and laboratory testing are also performed before and after CRT. Modifications to the post-CRT MRI protocol include the use of gradient echo cine imaging rather than steady state free precession imaging, application of wideband imaging to the LGE acquisitions, and strain imaging with cine Displacement Encoding with Stimulated Echoes (DENSE) tailored for device patients.