A case report of giant cell myocarditis complicated by severe heart failure: the value of early endomyocardial biopsy and mechanical circulatory support

Background: Giant cell myocarditis (GCM) is a rare, probably underdiagnosed and potentially fatal disease in young and middle-aged patients. Disease progression is often rapid, and life-threatening arrhythmias and cardiogenic shock due to progressive left ventricular failure are among the most feared complications. Although cardiac biomarkers and multimodality imaging are used as initial diagnostic tests in most patients, endomyocardial biopsy (EMB) is often required for a definitive diagnosis. However, there are still gaps in our knowledge in terms of the etiology, early diagnosis, management and prognosis of GCM. Case Description: We present the case of a male patient in his early 50s admitted to Haukeland University Hospital with fulminant GCM. He had no significant medical history in the past apart from hypertension, and presented to hospital in cardiogenic shock after a few weeks of progressive shortness of breath. Rapid initiation of methylprednisolone had an immediate effect on reducing myocardial inflammation, and sustained treatment with a combination of immunosuppressive agents along with optimal heart failure medications led to complete recovery of the heart function and clinical remission over several years. The case study highlights the urgency of an early EMB, access to mechanical circulatory support (MCS) and the efficacy of immunosuppressive treatment and optimal medical management for heart failure. Finally, our review of the literature also provides an updated guidance on the contemporary management of GCM patients. Conclusions: Accurate and early diagnosis with EMB in patients with GCM are crucial for better outcomes. Rapid initiation of methylprednisolone reduces myocardial inflammation and the risk of death. Sustained treatment with a combination of immunosuppressive agents together with optimal heart failure medications are essential for myocardial recovery and long-term stabilization. The use of MCS is the cornerstone in the management of GCM with a clear survival benefit.