Inclusion Criteria:  Male or female, age 18 years or older at the time of signing informed consent. On the heart transplant waiting list and expected to receive a heart transplant. Able to read, understand and provide written informed consent. Able and willing to comply with the study visit schedule, study procedures and study requirements.  Exclusion Criteria:  Heart transplantation has been performed. Concurrent multiple solid organ or tissue transplant Prior history of any organ or cellular transplantation. Planned use of other commercially available or investigational cfDNA or gene expression profile assays. Pregnant. Hemodynamically unstable or other serious medical condition that may adversely affect the subject's ability to participate in the study