1. Cardiology Unit, Ospedale del Cuore, Fondazione Toscana “G. Monasterio”, 54100 Massa, Italy
2. Institute of Clinical Physiology, National Research Council, Via Aurelia Sud, 54100 Massa, Italy
3. Fondazione Toscana Gabriele Monasterio, Via Aurelia Sud, 54100 Massa, Italy