To conduct a prospective randomised study to show the efficacy of immune suppression with prednisolone, administered at the 3-month duration of acute myocarditis.

The diagnosis of acute viral myocarditis was made based on echocardiography and serum viral antibodies. The inclusion criterion was acute myocarditis of 3 months duration. In all, 68 of 173 children were available for randomisation into a prednisolone-treated group of 44 and a control group of 24 children. The follow-up period in the prednisolone-treated group was 15.1 plus or minus 9.2 months and 13.6 plus or minus 10.6 months for the control group.

Compared with controls, 1 month after randomisation significantly more children in the prednisolone-treated group increased their ejection fraction to more than 40% (p = 0.029). Discrete analysis of change in the ejection fraction from the one at randomisation to one after 1 month of randomisation of greater than 10% and less than 10% or no change between groups showed a significantly greater number with improvement in the prednisolone-treated group (p = 0.019). At the end of the follow-up visits, a significantly larger number of children in the prednisolone-treated group had an ejection fraction of more than 60% compared with the control group (p = 0.049).

It is concluded that immune suppression with prednisolone, administered at 3 months of the onset of acute myocarditis, is effective in significantly bringing about improvement and cure in persistent left ventricular failure.