Efficacy of steroid therapy for pacing failure in a patient with chronic myocarditis.

A 66-year-old man had a progressive increase in the pacing threshold over a one-year period, resulting from chronic myocarditis. Following steroid therapy, the pacing threshold decreased and became stabilized, and was accompanied by a decrease in the serum creatine kinase, cardiac myosin light chains and pro-collagen III peptide values, but cardiac function did not improve. Endocardial biopsy showed that there was no progression in the fibrosis.