Abstract 14413: Possible Antibody Mediated Cardiac Rejection After Combined Heart-Kidney Transplant in a Sensitized Patient Associated to COVID-19 Pneumonia

Abstract

Background: Antibody mediated rejection (AMR) starts with the appearance of donor-specific antibodies (DSA), followed by graft injury that may be subclinical and can progress to cardiac allograft vasculopathy (CAV) and chronic graft dysfunction. Case report A 48-year-old man with a past medical history of right nephrectomy due to congenital renal atrophy and dilated cardiomyopathy required heart transplantation at age 31, presented an episode of AMR grade 2 ten years post-transplant developing CAV with graft loss and end-stage renal disease. He was listed for a combined heart-kidney transplant. His panel reactive antibody (PRA) level was 40%, requiring desensitization therapy (plasmapheresis, intravenous gamma globulin and rituximab). At age 44, he received a heart-kidney transplant. Methylprednisolone and rabbit antithymocyte globulin were used for induction and desensitization therapy with plasmapheresis and intravenous gamma globulin at months 0-3-6-12 was continued. Maintenance immunosuppression therapy continued with tacrolimus, mycophenolic acid and prednisone. During follow-up persistent circulating DSA anti-class II HLA were detected and PRA reached 80%. He was admitted with a multifocal COVID-19 pneumonia. He had received 4 doses of the messenger RNA vaccine BNT162b2. Dexamethasone was started and mycophenolic acid was discontinued for 14 days. He did not need mechanical ventilation. Echocardiogram revealed marked concentric LVH, LVEF = 60%, grade II diastolic dysfunction and reduced global longitudinal strain (-7,6%). Pro-BNP was 962 pg/ml, and Troponin T 100 pg/ml. Endomyocardial biopsy showed no signs of cellular rejection nor capillary injury. Immunopathologic findings were negative. Coronary angiogram showed no significant lesions. AMR was suspected, the patient was treated with methylprednisolone, plasmapheresis and intravenous gamma globulin. Clinical response was satisfactory, and he was discharged in functional class I (NYHA). Conclusions Although both histological and immunopathologic studies were negative, clinical suspicion for AMR in a highly sensitized patient prevailed in the context of a recent infectious intercurrence. Other diagnosis cannot be completely ruled out in this clinical scenario.