1. Department of Cardiology, University Hospital Ramon y Cajal, Carretera de Colmenar Km 9.100, 28034 Madrid; Spain
2. Department of Cardiology, Centro Hospitalar Universitário Lisboa Norte (CHULN), CCUL, Universidade de Lisboa, Av. Prof. Egas Moniz MB 1649-028 Lisboa, Portugal
3. Department of Cardiology, Bristol Heart Institute, University Hospitals Bristol and Weston NHS Trust and University of Bristol, UK