Granulomatous Myocarditis After Cardiac Transplantation for Giant Cell Myocarditis

Abstract

<h3>Introduction</h3> Cardiac sarcoidosis and idiopathic giant cell myocarditis are uncommon but serious inflammatory cardiomyopathies which share some clinical and histopathologic features. We present the case of a patient who developed end-stage heart failure due to giant cell myocarditis requiring heart transplant, and years after transplantation, developed cardiac sarcoidosis <h3>Case Report</h3> A 45-year-old man with no significant medical history was preparing for a triathlon but began to experience subacute heart failure symptoms culminating in a sudden cardiac arrest shortly after endomyocardial biopsy (EMBx) revealing giant cell myocarditis. He required ECMO cannulation as a bridge to biventricular HeartWare HVADs and was treated with cyclosporin. After 10 months of biventricular support, he underwent heart transplant. Post-operative course was uneventful and was maintained on standard immunosuppression with tacrolimus, mycophenolate, and prednisone. At three-years post-transplant, he was transitioned to sirolimus and remained stable. During his sixth annual visit, he noted exertional intolerance. His echocardiogram revealed a drop in his left ventricular ejection fraction from 58% to 47%, an increase LVIDd from 41 mm to 51 mm, and an increase in LV mass index from 70 to 80 g/m2. He also had a cardiopulmonary exercise stress test and his peak VO2 went from 36 ml/(min/kg) to 32.9 (ml/min/kg). Event monitor showed PVC's and non-sustained VT. Coronary angiogram showed mild non obstructive cardiac allograft vasculopathy. Endomyocardial biopsy revealed an active granulomatous myocarditis which had the appearance of sarcoidosis. His steroid regimen was augmented to prednisone 30 mg daily, then tapered. Three months after immunosuppression changes, cardiac PET scan revealed findings compatible with an inflammatory cardiomyopathy process associated with edema, fibrosis and scar. Tacrolimus was added to his regimen, mycophenolate dose was increased and received 3 days of pulse dose steroids <h3>Summary</h3> While previous descriptions of recurrent sarcoidosis in cardiac allografts have been described, the unique features of GCM on native heart explantation and clear features of sarcoidosis in the allograft despite adequate immunosuppression highlight not only the challenges with regard to management of active myocarditis after transplant but also the overlap of the two disease entities