1. From the Division of Cardiology, Department of Medicine, Baylor College of Medicine, Houston, Tex (M.L., M.A.Q., R.H., Q.T.Y., R.R., A.J.M.) and Division of Cardiology and the Center for Cardiovascular Research, the Toronto Hospital, Ontario, Canada (A.O., H.R., D.W., C.C.L., M.S.).