[1] Univ Hosp Parma, Cardiol, Parma, Italy
[2] St Petersburg State Med Univ, Cardiol Dept, St Petersburg, Russia
[3] Fatebenefratelli Hosp Benevento, Cardiol Div, Benevento, Italy
[4] San Luca Hosp, Cardiol Dept, Lucca, Italy
[5] Univ Clin Ctr Serbia, Cardiol Clin, Belgrade, Serbia
[6] Univ Hosp Vittorio Emanuele, Cardiothorax Vasc Dept, Echocardiog Lab, Catania, Italy
[7] Univ Naples 2, Monaldi Hosp, Cardiol Dept, Echocardiog Lab, Naples, Italy
[8] Invest Med, Cardiodiagnost, Buenos Aires, DF, Argentina
[9] Med Univ Lodz, Dept Cardiol, Lodz, Poland
[10] Hosp San Jose, Cardiol Div, Criciuma, Brazil
[11] Ramos Mejia Hosp, Cardiol Dept, Buenos Aires, DF, Argentina
[12] Acibadem City Clin Cardiovasc Ctr, Univ Hosp, Sofia, Bulgaria
[13] Univ Hosp St John God, Cardiol Dept, Salerno, Italy
[14] Univ Hosp St John God, Echocardiog Lab, Salerno, Italy
[15] CNR, Biomed Dept, Inst Clin Physiol, Pisa, Italy