Recurrent giant cell myocarditis after heart transplant: a case report.

Background: Giant cell myocarditis (GCM) is a rare but well-known cause of fulminant myocarditis. Despite optimal medical therapy, many patients progress to orthotopic heart transplant (OHT). We present a case of recurrent GCM following OHT, including complex considerations in patient management and infectious sequelae. Case summary: A 33-year-old previously healthy male presented with 2 months of worsening shortness of breath. Transthoracic echocardiogram (TTE) demonstrated a left ventricular ejection fraction of 30-35%. After ruling out an ischaemic aetiology, he was discharged on guideline-directed medical therapy and later presented with productive cough, worsening dyspnoea on exertion, and diarrhoea. He was found to have elevated troponins and N-terminal pro-brain natriuretic peptide, lactic acidosis, progression of severe bi-ventricular dysfunction on TTE and right heart catheterization, and low cardiac index (1.0 L/min/m2) requiring inotropes. He then required left ventricular assist device as a bridge to OHT. Pathology of the apical core diagnosed GCM as the cause of his fulminant heart failure. He eventually underwent heart transplantation, which was complicated by recurrent GCM. Treatment required intensification of his immunosuppressive regimen, which led to multiple infectious sequelae including norovirus, Shiga-like toxin producing Escherichia coli, and disseminated nocardia of the lung and brain. As of the most recent follow-up, the patient is currently clinically stable. Discussion: Although recurrent GCM after OHT has been reported in the literature, the prognosis is not well understood and there are no clear guidelines regarding management. This case summarizes clinical considerations, treatment strategies, and adverse effects of recurrent GCM treatment.