Giant Cell Myocarditis after Orthotopic Heart Transplant

Abstract

Introduction Giant cell myocarditis (GCM) is a rare, T-lymphocyte driven, inflammatory disease that leads to severe myocardial dysfunction and high morbidity. De novo occurrence of GCM after orthotopic heart transplant has not been reported and there is currently little evidence to guide management. Here we present a case of new onset GCM after orthotopic heart transplant (OHT) successfully treated with high dose steroids. Case Report A 66-year-old male with end stage heart failure due to ischemic cardiomyopathy underwent OHT complicated by cytomegalovirus viremia treated with valganciclovir. His immunosuppression regimen included tacrolimus 1.5mg twice a day, mycophenolate mofetil 1g twice a day, and prednisone 15mg daily. Three months after transplant, he was found to have acute cellular rejection (grade 2R) on routine endomyocardial biopsy (EMB) and treated with pulse dose steroids. EMB one month later demonstrated a focus of giant cell and histiocytes with surrounding interstitial and perivascular inflammation, suggesting a diagnosis of GCM (Figure 1A). An echocardiogram showed an ejection fraction of 54% without wall motion abnormalities, and mildly depressed right ventricular systolic function. He was treated with methylprednisone 1g daily for three days followed by a prolonged prednisone taper in addition to sirolimus 0.5 mg daily and tacrolimus 1.5 mg twice a day. Giant cell was absent on EMB one month later, suggesting response to therapy (Figure 1B). Patient was doing well without complications six weeks after diagnosis. Summary We present a case of GCM diagnosed on EMB in a patient who is status post orthotopic heart transplant, successfully treated with high dose steroids and immunosuppressive therapy. It is important to note that there were no giant cells in his heart explant and that we cannot definitely rule out sarcoidosis. This case however highlights the importance of early diagnosis of GCM and prompt treatment. Further studies are needed to determine the optimal treatment strategy for these patients.