1. Division of Cardiology, Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, MD (M.S., R.N., D.B., G.Z., B.L.L., A.S., D.I.L., D.A.K.).
2. Department of Medicine, Karolinska Institutet, Solna, Sweden (M.S.).
3. Department of Cardiology, Karolinska University Hospital, Stockholm, Sweden (M.S.).