1. From the Cardiovascular Division (Z.C., C.S., C.R., D.I.S.), Brigham and Women’s Hospital, Harvard Medical School, Boston, Mass; Harvard-M.I.T. Division of Health Sciences and Technology (C.R.), Massachusetts Institute of Technology, Cambridge, Mass; and Pharmacyclics, Inc (K.W.W., D.C.A.), Sunnyvale, Calif.