Treatment of myocarditis and cardiomyopathy in the USA

Abstract

The most active issue in the treatment of myocarditis is the question of efficacy of immunosuppressive therapy. This has not been resolved, although many practitioners have adopted the view that such therapy is helpful, based on uncontrolled, anecdotal but encouraging reports. The incidence of myocarditis has been reported to be anywhere from 2% to 63%, and inflammatory myocardial disease is probably not as uncommon as previously thought. Part of the problem of diagnosis may involve the need for early detection, which will probably necessitate noninvasive screening due to the cost of biopsy. The most promising tool in this area appears to be radioisotope imaging, gallium 67 scanning heading the list. This technique has not been proven to be sufficiently specific, but does enhance the chance of obtaining a positive biopsy. A large multicenter trial has been conceived and organized, involving 20 institutions in the USA and abroad. This will employ three limbs of randomized therapy for biopsy-proven myocarditis: (a) conventional, nonimmunosuppressive treatment only, (b) prednisone and azathioprine, and (c) cyclosporine and low-dose prednisone. We hope this study will answer several questions regarding the appropriate therapy of myocarditis. Treatment of dilated cardiomyopathy now includes as standard the use of various vasodilators, which seem definitely to improve functional status and well-being, but not survival. Several new inotropic agents are under investigation, some of which may prove to be more than just vasodilators. Assessment of functional performance and mechanical reserve is of great interest with regard to therapy, and new invasive and noninvasive techniques are under continued development. Hypertrophic cardiomyopathy, whose hemodynamic lesion appears to be diastolic rather than systolic function, is certainly of great interest, and most current research involves calcium-channel blockers. Arrhythmias are a well-recognized cause of morbidity and mortality in both hypertrophic and dilated cardiomyopathies. Research in the recognition and treatment of ventricular electric instability in cardiomyopathy is affecting treatment.