Pharmacotherapy of dilated cardiomyopathy: current status and future directions.

The current status and future directions of the pharmacotherapy of dilated cardiomyopathy are reviewed. The Japanese multicenter study on the effect of beta-blockers revealed significant improvement of NYHA functional classification, LV end-diastolic dimension, ejection fraction, and exercise tolerance time in patients with dilated cardiomyopathy. From our study using normal rabbits, metoprolol augmented adenylate cyclase activity without upregulation of the beta-adrenergic receptor number. Carteolol, a beta-adrenergic blocker with intrinsic sympathomimetic action, prevented the development of dilatation and hypertrophy of the heart in the chronic stage following murine encephalomyocarditis (EMC) viral myocarditis. Metoprolol exerted no such effect. Animal experiments indicated that immunosuppressive treatment for inflammatory myocarditis may aggravate the clinical course of the disease. However, immunosuppressive treatment in acute myocarditis should be reevaluated with the use of newly developed antiviral agents. A new synthetic immunoactive peptide FK 565, given before or simultaneously with viral inoculation, proved effective in inhibiting myocardial virus replication and myocardial damage in murine EMC viral myocarditis. Beneficial effects of captopril on survival rate and myocardial injury were demonstrated dose dependently in murine EMC viral myocarditis, even when the treatment was started around the peak of virus replication, namely, on day 4-14 after inoculation. Captopril may be promising for the treatment of acute myocarditis, and hopefully for prevention of the progression from myocarditis to dilated cardiomyopathy.