From the Institute for Clinical Evaluative Sciences (S.S.O., P.C.A., J.V.T., D.S.L.), the Institute for Medical Sciences, University of Toronto (S.S.O., D.S.L.), Sunnybrook Health Sciences Centre (J.V.T.), and the Peter Munk Cardiac Centre and the Joint Department of Medical Imaging, University Health Network, University of Toronto, Canada (D.S.L.).