Giant-cell myocarditis (GCM) is a rare, rapidly progressive, and frequently fatal myocardial disease. Based on endomyocardial or surgical biopsy, GCM is histologically defined by multinucleated giant cells, a lymphocytic inflammatory infiltrate, and myocyte necrosis. It is often found in association with various immune-related systemic disorders.20 Patients present with heart failure, ventricular arrhythmias, and atrioventricular block that fails to improve with standard therapy.21
Treatment and Management
The typical management of acute myocarditis includes supportive care for left ventricular dysfunction and arrhythmia control.22 Many of the standard heart failure therapies—β-blockers, ACE inhibitors, angiotensin receptor blockers, and aldosterone antagonists—are efficacious; several, at least in animal models, appear to exert anti-inflammatory as well as the standard cardiovascular effects.23
Caution is advised regarding the selection of specific therapies. For example, in one study, metoprolol produced deleterious effects in acute murine Coxsackie virus myocarditis; inflammation, necrosis, and mortality significantly increased in the treatment group, compared with the placebo group.23
Information on the effects of particular therapies for specific etiologies of myocarditis are limited, but some evidence supports immunosuppressive and immune-modulating therapies for chronic, virus-negative inflammatory cardiomyopathy. Immunosuppressive therapy is also beneficial for acute GCM and sarcoidosis.23 For patients with myocarditis associated with celiac disease, a gluten-free diet alone or in combination with immunosuppressive agents can significantly improve clinical outcomes.12
OUTCOME FOR THE CASE PATIENT
Because the patient was already taking a statin and an ACE inhibitor for hypercholesterolemia and hypertension, respectively, as well as one baby aspirin per day, only a β-blocker was added to his discharge medication regimen.
Three months after hospital discharge, the patient underwent repeat CMR imaging. The ejection fraction had markedly improved to the 55%-to-60% range, although extensive midmyocardial-to-epicardial scarring in a multifocal pattern, primarily involving the basilar anterior and anterolateral wall, was still present, as was a small focus of an active (albeit healing) process in the inferior wall. Clinically, the patient was doing reasonably well and was vigorously exercising daily without dizziness, syncope, chest discomfort, or shortness of breath.
However, within several weeks of discharge, the patient reported having one two-hour episode of frequent palpitations at rest. Since that episode, palpitations have occurred infrequently. A 48-hour Holter monitor was ordered to better evaluate the palpitations and showed only rare premature ventricular contractions and isolated premature atrial contractions; no complex ectopy was noted. A follow-up stress echocardiogram was scheduled for 12 months, assuming the patient was free of clinical signs and symptoms of heart failure and arrhythmias at that time.
CONCLUSION
Myocarditis can manifest with a broad spectrum of signs and symptoms that may make its identification difficult, especially if a cardiac source is not initially considered in the differential diagnosis. However, for patients who present with elevated biomarkers and normal coronary artery anatomy, the identification of myocarditis is relatively easy; the difficulty in this circumstance relates to the identification of the specific etiology of the myocarditis.
The long-term prognosis for myocarditis is frequently good and the treatment straightforward, using medications that are modeled after standard heart failure therapy. However, depending on the etiology, specific treatment may be advisable—or required—in order to improve outcomes.
References
1. Fabre A, Sheppard MN. Sudden adult death syndrome and other nonischaemic causes of sudden cardiac death: a UK experience. Heart. 2006;92:316-320.
2. Doolan A, Semsarian C, Langlois N. Causes of sudden cardiac death in young Australians. Med J Aust. 2004;180:110-112.
3. Felker GM, Hu W, Hare JM, Hruban RH, et al. The spectrum of dilated cardiomyopathy: the Johns Hopkins experience with 1,278 patients. Medicine (Baltimore). 1999;78:270-283.
4. Leitman M, Tyomkin V, Peleg E, et al. Left ventricular function in acute inflammatory peri-myocardial diseases—new insights and long-term follow-up. Cardiovasc Ultrasound. 2012;10:42.
5. Blauwet LA, Cooper LT. Myocarditis. Prog Cardiovasc Dis. 2010;52:274-288.
6. Testani JM, Kolansky DM, Litt H, Gerstenfeld EP. Focal myocarditis mimicking acute ST-elevation myocardial infarction: diagnosis using cardiac magnetic resonance imaging. Tex Heart Inst J. 2006;33:256-259.
7. Friedrich MG, Sechtem U, Schulz-Menger J, et al. Cardiovascular magnetic resonance in myocarditis: a JACC white paper. J Am Coll Cardiol. 2009;53: 1475-1487.
8. Olimulder MA, van Es J, Galjee MA. The importance of cardiac MRI as a diagnostic tool in viral myocarditis-induced cardiomyopathy. Neth Heart J. 2009;17:481-486.
9. Mavrogeni S, Bratis K, Markussis V, et al. The diagnostic role of cardiac magnetic resonance imaging in detecting myocardial inflammation in systemic lupus erythematosus. Differentiation from viral myocarditis. Lupus. 2013;22:34-43.
10. Schultz JC, Hilliard AA, Cooper LT, Rihal CS. Diagnosis and treatment of viral myocarditis. Mayo Clin Proc. 2009;84:1001-1009.
11. Schuppan D, Dieterich W. Pathogenesis, epidemiology, and clinical manifestations of celiac disease in adults (2013). www.uptodate.com/contents/pathogenesis-epidemiology-and-clinical-manifestations-of-celiac-disease-in-adults. Accessed November 14, 2013.