1. From Mount Sinai School of Medicine (H.K., D.S., A.V., M.D.Y.), New York, NY; Clinical Neurocardiology Section (D.S.G., C.H.), National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Md; and Beth Israel Deaconess Medical Center (R.N., R.F.), Boston, Mass.