1356621 - Imaging the two hearts - A case of suspected rejection in a cardiac heterotopic transplantation

Description of Clinical Presentation: A 19 years-old male patient with previous heterotopic cardiac transplantation for dilated cardiomyopathy in 1995 presented with recurrent episodes of exertional chest pain. He was managed for a previous episode of moderate rejection with impairment of left ventricular (LV) function in 2005. Subsequent antibody-mediated reaction (AMR) was treated with corticosteroids. He had undergone multiple percutaneous coronary interventions (PCI) over the years for recurrent graft vascular disease (GVD). He also had a renal transplant in 2015 for chronic kidney disease due to calcineurin inhibitor nephrotoxicity.

Diagnostic Techniques and Their Most Important Findings: In the cine images, the native heart appears severely impaired with a left ventricular ejection fraction (LVEF) of 24%. The donor heart had also severe systolic dysfunction (LVEF of 31%) and severe hypokinesia of the septum (Figure 1). T2 mapping for quantification of myocardial oedema showed no convincing myocardial oedema in either heart (~46 ms in the septum, normal values at our institution < 52 ms). Native T1 values were also within the normal ranges ( ~1002 ms) as well as ECV values (~29%, Figure 2). After gadolinium contrast injection there was no evidence of LV thrombus in the native heart on early imaging, with no important delayed enhancement. Within the donor heart, subendocardial delayed enhancement was noted in the entire septum extending to the apical cap. Adenosine stress quantitative perfusion mapping demonstrated no regional inducible perfusion defects, confirming the absence of regional perfusion defects, but demonstrated globally reduced myocardial blood flow during stress at 1.25 ml/gr/min with globally reduced myocardial perfusion reserve at 1.49 (Figure 3). The absence of regional perfusion defect at both qualitative and quantitative stress perfusion images was reassuring, suggesting no focal epicardial disease in the donor heart, although in keeping with previously reported low myocardial blood flow values in patients with previous rejection episodes, likely related to microvascular ischaemia. Oedema and LGE imaging also did not suggest acute rejection (clinically unlikely), and the patient was discharged on optimised medical therapy with a plan for further surveillance.

Learning Points from this Case: Vasodilator stress perfusion imaging is challenging in cardiac transplant patients, due to higher baseline heart rate and cardiac denervation, but feasibility in this population and accuracy in diagnosing patients with GVD is well-recognised. CMR represents an excellent one-stop shop imaging modality for the evaluation of transplant patients, particularly when presenting with chest pain, assessing not only LV function and regional wall motion abnormalities, but also myocardial oedema, diffuse fibrosis, myocardial infarction and inducible myocardial perfusion defects. The ability to separately ECG-gate and assess both hearts in a heterotopic circulation is unique to CMR and allows for the targeted assessment of 2 hearts in one patient.