[The characteristics of myocarditis in diphtheria in adults based on data from the 1993-1994 epidemic]

In 45% of 212 cases of diphtheria toxica in adults heart complications were observed. The earliest ECG signs are sinus bradycardia, AV dissociation, AV escape rhythms, prolongation of QT interval, high U wave (U > T, T + U wave). In the cases where differential diagnosis of myocarditis and other heart diseases in adults is difficult, the attention must be focused on the sickle-like depression ("sagging") of ST-interval that is a typical sign in diphtheric myocarditis. The most severe forms of diphtheric myocarditis are complicated by AV and intraventricular conduction disturbances and malignant ventricular arrhythmias.