Background: The true incidence and prognosis of myocarditis in children with acute dilated cardiomyopathy (DCM) at presentation remains uncertain. This study examines the incidence of lymphocytic myocarditis in a consecutive cohort of children with acute DCM at presentation and outcome after dual therapy immunosuppression with cyclosporine and steroids.
Methods: Twenty-nine consecutive children with acute DCM underwent early endomyocardial biopsy. Children with "definite" myocarditis comprised group I (n = 9) and were treated with cyclosporine and prednisolone. Group II (n = 2) had "borderline" myocarditis, and group III (n = 18) nonspecific histologic findings. Outcome was assessed by echocardiographic measurement of left ventricular end-diastolic dimension and fractional shortening, with follow-up endomyocardial biopsy in group I subjects.
Results: Myocardial inflammation with or without myocardial necrosis (groups I and II) was present in 38% of all cases. There were no initial clinical, electrocardiographic, or echocardiographic features to distinguish patients in group I from patients in group III. At presentation, the mean +/- SEM left ventricular end-diastolic dimension and fractional score-Z scores of group I patients were 4.6 +/- 1.7 and -5.1 +/- 0.8, respectively, compared with 0.8 +/- 0.3 and -0.9 +/- 0.4, respectively, at withdrawal of immunosuppression (p < 0.001 for both). Both of these parameters did not differ significantly from normal controls at least follow up. Two group I patients had a biopsy-proven relapse after withdrawal of therapy that responded to reinstitution of immunosuppression. At latest follow-up, all nine group I patients had regained normal left ventricular function compared with four of 18 group III patients (p < 0.001).
Conclusion: Lymphocytic myocarditis is frequent in children with dilated cardiomyopathy and cannot be predicted from noninvasive investigations. The use of cyclosporine and steroids is associated with a favorable outcome, and a controlled trial of dual therapy immunosuppression in children is therefore warranted.