OPtimal Adult Heart Transplant Immunosuppression With MicroRNA Levels (OPTIMAL)

The study objectives will be accomplished in a prospective, multicenter observational, longitudinal cohort study that includes \~250 Heart Transplant patients from the United States. Patients will be screened for eligibility and enrolled \~1 month (± 2 weeks) after transplant. Study participation will last 36 months. All patients will follow the center's standard of care surveillance schedule after transplant. Blood samples will be collected for miR evaluation at: 1. specified time intervals after transplant and 2. when a clinical event of interest occurs, including treated rejection, or infection. Research samples will be collected and used to evaluate miR expression as well as other biomarkers related to heart transplantation and immunosuppression medications. Additional data collection will include demographics, medical history, medications, human leukocyte (HLA)/donor specific antibody (DSA) evaluations, endomyocardial biopsy (EMB) echocardiography, donor-derived cell-free DNA (dd-cfDNA), and other post-transplant events and testing. This work will form the basis for a non-invasive, genomic blood test that can be used to monitor patients after heart transplant to mitigate complications of over-immunosuppression, such as infection, without increasing the risks of under-immunosuppression, such as rejection.