Sir.—I wish to congratulate Drs Miller and French for their excellent account of myocarditis in juvenile rheumatoid arthritis (JRA), which appeared in the February issue of the Journal (131:205, 1977). As they point out, the paucity of information on this important systemic feature of JRA is surprising, and their current article is thereby both timely and informative.
It has been my experience, like theirs, that myocarditis occurs most frequently in the systemic (acute febrile) form of JRA, and, in fact, constitutes the major hazard in this form of the disease.1 Myocarditis that remains undetected and untreated may have serious, if not fatal, consequences because it may rapidly induce cardiac enlargement and subsequent heart failure.
Pericarditis, which is more frequent than myocarditis, is usually a benign manifestation of JRA. Nevertheless, its early detection is important because it may herald impending myocarditis.1 Strangely, precordial pain or dyspnea are rarely