1. Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
2. DIBINEM, University of Bologna, 40126 Bologna, Italy
3. Heart Failure Unit, Cardiology Department, Guglielmo da Saliceto Hospital, 29121 Piacenza, Italy
4. Department of Cardiovascular Surgery, University Hospital Lausanne, 1011 Lausanne, Switzerland
5. Cardiac Surgery Unit, Department of Clinical and Experimental Medicine, University of Parma, Via A. Gramsci 14, 43126 Parma, Italy