During 1992 1996 we observed 122 children with diphtheria, 49 with the toxic form, in the region of Nizhny Novgorod in Russia. Sixty-four patients suffered from diphtheric carditis, 9 died. The clinical picture was characterized by a rapid development of heart and circulatory failure. ECG showed QRS alterations with intraventricular conduction impairment, sinus node dysfunction, ectopic rhythm disturbances and repolarization disturbances in all patients with carditis. Infarction-like ECG changes were typical for the pseudocoronary form with the worst prognosis. Echocardiographically there was left ventricular (LV) dilatation and depressed LV function, whereas LV muscle mass was increased. Myoglobin, LDH and CPK levels were elevated in each patient demonstrating significant differences between the various courses of disease.
Conclusion: In diphtheria, the extent of hypermyoglobinaemia (> 2000 ng/ml) and an increased LDH1/LDH2 (> 1) ratio are reliable markers for the development of carditis indicating a poor prognosis.