Inflammatory cardiomyopathy (myocarditis): which patients should be treated with anti-inflammatory therapy?

Abstract

In patients presenting with congestive heart failure in the United States, approximately one-quarter have idiopathic dilated cardiomyopathy (IDC). IDC is thought to result from a number of mechanisms that injure the myocardium and lead to a common pathway of cardiac dilatation and heart failure. Known mechanisms of myocardial injury include alcohol, toxins, infections, cytotoxic chemotherapy, and metabolic abnormalities.1 Recent studies have highlighted important genetic links, suggesting that familial transmission is important in a subgroup of IDC patients. However, in most IDC patients, a cause cannot be determined. Substantial animal experimental data has demonstrated a strong pathogenetic link between infectious agents (usually viruses) and subsequent immune-mediated damage to the myocardium resulting in IDC.2 3 Human studies have demonstrated a high prevalence of viral genome in the hearts of patients with IDC. Enteroviruses, adenovirus, influenza, HIV, and hepatitis C have been implicated in the pathogenesis of dilated cardiomyopathy and myocarditis. Much of the data suggests cell-mediated immune damage, although cytokines and antibodies have also been hypothesized to play a role.3 4 Patients with heart failure due to IDC should be treated with conventional heart failure regimens, including diuretics, angiotensin-converting enzyme (ACE) inhibitors, digitalis, β-blockers, vasodilators, aldosterone antagonists, and other effective medications and technology. However, the specific question for patients with an inflammatory cardiomyopathy is whether a regimen designed to reduce or eliminate inflammation would provide added clinical benefit compared with conventional heart failure therapy. This has been a difficult question to answer for several reasons. First, the clinical presentation of inflammatory cardiomyopathy is very heterogeneous. Most patients with myocarditis are asymptomatic, and their condition often resolves spontaneously.5 Another group of myocarditis patients present with a fulminant course characterized by severe heart failure, cardiogenic shock, and a high death rate .6 Use of mechanical assist devices in this …