This study focuses on adults who are undergoing heart transplant evaluation or are on the waiting list and expected to receive a heart transplant. The purpose of the study is to determine whether an investigational blood test called Prospera (also known as cell-free DNA testing) can be used in patient care instead of heart biopsy. Researchers aim to describe the association between Prospera and other procedures used to detect heart transplant rejection and/or injury in the first year after transplant. Study procedures include blood draws and data collection from MRIs and echocardiograms. Sometimes, a transplanted heart is rejected by the body. To detect rejection, doctors may order blood or imaging tests or perform a heart biopsy. Prospera is used to aid detection of risk for allograft rejection by finding DNA from the transplanted organ in the blood. When there is an increase in DNA from the donor heart in the patient’s blood, there may be a higher chance of rejection.