Inclusion Criteria:  Exposed:  Heart transplant recipients  "De novo" antiHLA detection (after heart transplant):  Mean fluorescence intensity (MFI)) > 2000 for donor-specific antibodies Standard fluorescence intensity (SFI) > 150 000 for non-donor specific antibodies  Detailed immunological history:  Determination of anti-HLA antibodies before heart transplant. Serial determination of anti-HLA antibodies during heart transplantation follow-up Known HLA typing of the donor. Non-exposed: Heart transplant procedure contemporary to the index case with negative anti-HLA antibodies.  Exclusion Criteria:  Recipient of a second HT Multiple organ transplantation Unknown immunological history Recipients sensitized with anti-HLA antibodies against donor's HLA before the transplant CMR contrast will not be administered in patients with glomerular filtration rate < 30 ml/kg/1.73m2 Patients with implanted cardiac devices or any other magnetic resonance non-compatible metallic prosthetic material will not undergo CMR.