This is an open label Comparative Effectiveness Research (CER) study in which patients will be randomized at the site level to Prospera surveillance or EMB surveillance in a 2:1 ratio (Prospera to EMB) at each site. Subjects will be enrolled into the study while under evaluation for heart transplantation or on the transplant waiting list prior to heart transplantation. All subjects will follow the center's standard of care surveillance schedule from transplant through 4 weeks post-transplantation. EMB during this phase is expected to occur roughly weekly or bi-weekly. Study group assignment will take place at randomization. Subjects will be randomized 30 days (± 10 days) post-transplant to Prospera surveillance versus EMB surveillance in a 2:1 ratio. Rejection surveillance (Prospera Group and EMB Group) will be performed at times corresponding to the institutional standard of care schedule for rejection surveillance.