Debate Continues over Best Treatment for Myocarditis

Controversy continues to surround the most effective approach to the management of patients with myocarditis, according to HFSA, which recently released updated recommendations as part of the 2010 Comprehensive Heart Failure Practice Guidelines.

Myocarditis, an entity with a wide variety of cardiac manifestations, including heart failure (HF), is characterized by both an active inflammatory cellular infiltrate within the myocardium and associated myocyte necrosis, according to the Dallas pathologic criteria. Although many clinicians consider the Dallas criteria too restrictive, the classification has established uniform histologic criteria for diagnosis and has substantially reduced the wide variation in reported rates of the disease.

The clinical features of myocarditis are extremely varied, ranging from asymptomatic electrocardiographic abnormalities observed during viral Coxsackie B outbreaks in the community, to severe dilated cardiomyopathy with fulminant HF leading to transplantation or death. Myocarditis may also cause ventricular arrhythmias or heart block or mimic acute myocardial infarction. Both acute and chronic dilated cardiomyopathies may result from inflammatory heart disease.

The histologic differentiation of myocarditis from idiopathic dilated cardiomyopathy remains problematic, because several published series suggest no difference in long-term prognosis, regardless of the presence or absence of myocardial inflammation. Still, many clinicians believe that myocarditis is a potentially reversible form of cardiomyopathy, and the search for its presence continues through the use of endomyocardial biopsy.

In terms of the best therapeutic approach for patients considered to have myocarditis, the HFSA issues the following recommendations based on a review of available data from evaluations of immunomodulatory therapy for the management of myocarditis:

• Routine use of immunosuppressive therapies is not recommended for patients with myocarditis.
• Endomyocardial biopsy should be considered in patients with an acute deterioration of cardiac function of unknown etiology who are unresponsive to medical therapy.