The
n e w e ng l a n d j o u r na l
of
m e dic i n e
review article Medical Progress
Myocarditis Leslie T. Cooper, Jr., M.D.
From the Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN. Address reprint requests to Dr. Cooper at the Division of Cardiovascular Diseases, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, or at cooper.leslie@mayo.edu. N Engl J Med 2009;360:1526-38. Copyright © 2009 Massachusetts Medical Society.
M
yocarditis may present with a wide range of symptoms, ranging from mild dyspnea or chest pain that resolves without specific therapy to cardiogenic shock and death. Dilated cardiomyopathy with chronic heart failure is the major long-term sequela of myocarditis. Most often, myocarditis results from common viral infections; less commonly, specific forms of myocarditis may result from other pathogens, toxic or hypersensitivity drug reactions, giant-cell myocarditis, or sarcoidosis. The prognosis and treatment of myocarditis vary according to the cause, and clinical and hemodynamic data usually provide guidance to decide when to refer a patient to a specialist for endomyocardial biopsy. The aim of this review is to provide a practical and current approach to the evaluation and treatment of suspected myocarditis.
Defini t ion The standard Dallas pathological criteria for the definition of myocarditis require that an inflammatory cellular infiltrate with or without associated myocyte necrosis be present on conventionally stained heart-tissue sections (Fig. 1A).1 These criteria are limited by variability in interpretation, lack of prognostic value, and low sensitivity, in part due to sampling error.2,3 These limitations have led to alternative pathological classifications with criteria that rely on cell-specific immunoperoxidase stains for surface antigens, such as anti-CD3, anti-CD4, anti-CD20, anti-CD68, and anti–human leukocyte antigen (Fig. 1B).4,5 Criteria that are based on immunoperoxidase staining have greater sensitivity and may have prognostic value.6 Preliminary studies suggest that noninvasive cardiac magnetic resonance imaging (MRI) may provide an alternative method for diagnosis without the risks of biopsy. For example, regions of myocarditis are reported to correlate closely with regions of abnormal signal on cardiac MRI.7,8 The lack of consensus regarding the value of invasive studies such as endomyocardial biopsy and the overall good prognosis for patients with mild, acute dilated cardiomyopathy who have suspected myocarditis have led to recent recommendations that endomyocardial biopsy should be considered on the basis of the likelihood of finding specific treatable disorders.9 Clinicopathological criteria may distinguish fulminant lymphocytic myocarditis from acute lymphocytic myocarditis and introduce prognostically useful information that improves on purely pathological classifications.10 On the basis of clinicopathological criteria, fulminant lymphocytic myocarditis, which has a distinct onset with a viral prodrome within 2 weeks before the onset of symptoms and hemodynamic compromise but has a generally good prognosis, may be distinguished from acute lymphocytic myocarditis, which frequently does not have a distinct onset and hemodynamic compromise but more frequently results in death or the need for cardiac transplantation (Table 1).11,12 Two caveats are important when using such clinicopathological criteria. First, even though patients with fulminant lymphocytic 1526
n engl j med 360;15 nejm.org april 9, 2009
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