[1] Hosp Univ Penn, Cardiovasc Med Div, Cardiac Electrophysiol, 9 Founders Pavil Cardiol,3400 Spruce St, Philadelphia, PA 19104 USA
[2] Univ Padua, Dept Cardiac Thorac Vasc Sci & Publ Hlth, Unit Biostat, Padua, Italy
[3] Hosp Univ Penn, Cardiovasc Med Div, Adv Heart Failure Unit, 3400 Spruce St, Philadelphia, PA 19104 USA