University of Padua - Department of Cardiac, Thoracic, and Vascular Sciences, Stanford University - Department of Pathology, Sorbonne University - Department of Cardiac Surgery, University of California, Los Angeles (UCLA) - UCLA Immunogenetics Center, Washington University in St. Louis School of Medicine, Paris Expertise Centre for Organ Transplantation at Paris Cardiovascular Research Center (PARCC), Cedars-Sinai Medical Center - Smidt Heart Institute, Hospices Civils de Lyon - Department of Transplantation Nephrology and Clinical Immunology, Papworth Hosptial - The Cardiothoracic Transplant Unit, University of Padua - Department of Cardiac, Thoracic, and Vascular Sciences, University Hospitals Birmingham NHS Foundation Trust, Paris Expertise Centre for Organ Transplantation at Paris Cardiovascular Research Center (PARCC), Necker-Enfants Malades Hospital, Paris Expertise Centre for Organ Transplantation at Paris Cardiovascular Research Center (PARCC) and Intermountain Cental Laboratory