New Non-Invasive Imaging Technologies in Cardiac Transplant Follow-Up: Acquired Evidence and Future Options

Abstract

Heart transplantation (HT) is the established treatment for end-stage heart failure, significantly enhancing patients' survival and quality of life. To ensure optimal outcomes, the routine monitoring of HT recipients is paramount. While existing guidelines offer guidance on a blend of invasive and non-invasive imaging techniques, certain aspects such as the timing of echocardiographic assessments and the role of echocardiography or cardiac magnetic resonance (CMR) as alternatives to serial endomyocardial biopsies (EMBs) for rejection monitoring are not specifically outlined in the guidelines. Furthermore, invasive coronary angiography (ICA) is still recommended as the gold-standard procedure, usually performed one year after surgery and every two years thereafter. This review focuses on recent advancements in non-invasive and contrast-saving imaging techniques that have been investigated for HT patients. The aim of the manuscript is to identify imaging modalities that may potentially replace or reduce the need for invasive procedures such as ICA and EMB, considering their respective advantages and disadvantages. We emphasize the transformative potential of non-invasive techniques in elevating patient care. Advanced echocardiography techniques, including strain imaging and tissue Doppler imaging, offer enhanced insights into cardiac function, while CMR, through its multi-parametric mapping techniques, such as T1 and T2 mapping, allows for the non-invasive assessment of inflammation and tissue characterization. Cardiac computed tomography (CCT), particularly with its ability to evaluate coronary artery disease and assess graft vasculopathy, emerges as an integral tool in the follow-up of HT patients. Recent studies have highlighted the potential of nuclear myocardial perfusion imaging, including myocardial blood flow quantification, as a non-invasive method for diagnosing and prognosticating CAV. These advanced imaging approaches hold promise in mitigating the need for invasive procedures like ICA and EMB when evaluating the benefits and limitations of each modality.

Keywords: atrial function; cardiac allograft vasculopathy; cardiac magnetic resonance; coronary computed tomography angiography; heart transplantation; strain echocardiography; stress echocardiography.

Figure 1

Two-dimensional left atrial strain using speckle tracking echocardiography obtained from the apical four-chamber (upper panel) and two-chamber (lower panel) views.

Figure 2

Cardiac computed tomography images showing cardiac allograft vasculopathy grade III according to the International Society for Heart and Lung Classification. Right coronary artery reconstruction with a calcific coronary plaque at the second tract assessed with cardiac computed tomography angiography (right panel) and his orthogonal views (left panel).

Figure 3

Cardiac computed tomography images showing cardiac allograft vasculopathy grade IV-A according to the International Society for Heart and Lung Classification with a non-calcific, sub occlusive coronary plaque at the second tract of the circumflex coronary artery assessed with cardiac tomography angiography.