How is giant cell myocarditis (GCM) diagnosed and treated?

Updated: Mar 02, 2021
  • Author: Vinh Q Nguyen, MD, FACC; Chief Editor: Gyanendra K Sharma, MD, FACC, FASE  more...
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Giant cell myocarditis (GCM) is a rare, rapidly progressive, and frequently fatal myocarditis. The clinical presentation is typically fulminant heart failure, ventricular dysrhythmias, and complete heart block. The myocardium is diffusely infiltrated by lymphocytes and multinucleated giant cells. The resulting necrosis and fibrosis leads to ventricular systolic dysfunction and fatal arrhythmias. 

The etiology can be secondary to viral infections, autoimmune disorders, and drug hypersensitivity. Inflammatory bowel disease and tumors have also been implicated. Acute cardiac structural findings include wall thickening with normal chamber size that typically dilates with disease progression. Right ventricular dysfunction often follows, which is an independent predictor of death and transplantation. [11]

Right ventricular endomyocardial biopsy (EMB) is used to guide therapy; biopsy has a higher sensitivity (82-85%) than that of other myocarditis counterparts due to its diffuse endocardial involvement for tissue sampling. [12]  Early diagnosis is key due to the high mortality nature of the pathologic process. As such, the 2007 American Heart Association, American College of Cardiology, and European Society of Cardiology (AHA/ACC/ESC) scientific statement recommends EMB as a class IB indication in unexplained new-onset heart failure of 2 weeks’ to 3 months’ duration that is associated with a dilated left ventricle, new ventricular arrhythmias, and heart block. [4]

Treatment of GCM is predicated on heart failure guideline–directed medical therapy plus immunosuppression with cyclosporine and corticosteroids; thus, timely diagnosis via EMB is prudent. [13, 14]  Treatment with cyclosporine and corticosteroids is associated with a median transplant-free survival of 12.3 months compared to 3 months without immunosuppression. [15]

The European Study of Epidemiology and Treatment of Cardiac Inflammatory Diseases (ESETCID) showed that there was no benefit in treatment of cytomegalovirus (CMV)-induced myocarditis treated with hyperimmunoglobulin, enterovirus-positive myocarditis treated with interferon alpha, and adenovirus-positive myocarditis treated with IgG and IgM immunoglobulin as compared with placebo. [16]

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