From the Cardiovascular Division (Z.C., T.F., A.C.Z., R.E., C.R., D.I.S.), Brigham and Women’s Hospital, Boston, Mass; Harvard-MIT Division of Health Sciences and Technology (C.R.), Cambridge, Mass; and Merck Research Laboratories (P.A.D., S.D.W.), Rahway, NJ. (At 2002-07-02)