A new Dawn: Advances and innovation in heart transplantation part I - cardiac magnetic resonance imaging in heart transplantation

Heart transplantation (HTx) remains the treatment of choice for patients with advanced heart failure. HTx recipients require intensive surveillance over time. Major complications that should be monitored, prevented, and treated in a timely manner include graft dysfunction secondary to cellular rejection or antibody-mediated rejection (AMR) and coronary allograft vasculopathy (CAV). While echocardiographic surveillance plays a key role in detecting major changes in graft function and endomyocardial biopsy remains the most widely used invasive technique for the surveillance of graft rejection, the role of cardiac magnetic resonance (CMR) imaging is expanding as a complementary non-invasive imaging modality capable of identifying structural, functional, and tissue characterization abnormalities associated with several graft complications. Providing detailed characterization of myocardial tissue, CMR may facilitate early detection of abnormalities suggestive of graft dysfunction and rejection through advanced techniques such as parametric mapping to assess edema, while also enabling longitudinal surveillance of fibrosis, adverse remodeling, and treatment response. Combining CMR with novel blood-based assays, such as donor-derived cell-free DNA, has the potential to improve non-invasive surveillance of late cellular rejection or AMR. Inevitable ischemic injury occurring during transplantation may affect CMR findings, even in the absence of other significant conditions, with late gadolinium enhancement (LGE) detection in 62% of rejection-free HTx recipients in the first year after HTx, with a low LGE extent of 2% on average, making the interpretation of pathological findings more difficult or uncertain compared with native hearts. In this review, we summarize the current evidence on the role of CMR in the follow-up of HTx recipients, highlighting its strengths, limitations, and complementary role in the assessment of graft dysfunction, rejection, and CAV.