Determining the Association of Microvascular Disease as Assessed by PET and Graft Injury by Donor Derived Cell Free DNA

Potential subjects must meet all of the following criteria to be eligible for inclusion in the study: General Inclusion Criteria: * The patient is over 18 years of age. * The patient underwent orthotopic heart transplantation and is undergoing routine cardiac allograft vasculopathy (CAV) surveillance with PET. * The patient has no evidence of cardiogenic shock. * The patient has no evidence of acute rejection. * The patient, or legally authorized representative, has been informed of the nature of the study, agrees to its provisions, and has provided written informed consent, approved by the appropriate Institutional Review Board (IRB) or Ethics Committee (EC). Potential subjects will be excluded if any of the following conditions apply: Exclusion Criteria: * Evidence of moderate to large area of ischemia on the PET. * Multiorgan transplantation. * Life expectancy \<1 year due to non-cardiac conditions. * Less than 3 years from transplantation. * Patient appears unlikely or unable to participate in the required study procedures, as assessed by the study PI, study coordinator, or designee (ex: clinically-significant psychiatric, addictive, or neurological disease).