1. Department of Medicine, Section of Cardiovascular Medicine, Boston Medical Center, Boston University, MA (C.A.).
2. Department of Cardiology, Herlev and Gentofte Hospital (M.S.), University of Copenhagen, Denmark.
3. The Heart Centre, Rigshospitalet (F.G.), University of Copenhagen, Denmark.
4. Department of Cardiology, Hillerød Hospital (C.T.-P.), University of Copenhagen, Denmark.