[Cardiac complications in adult diphtheria: analysis of 212 cases].

In a series of 212 cases of diphtheria toxica in adults 90 (42%) suffered from cardiac complications. While early clinical signs were lacking or unspecific, the diagnosis could be suspected based on changes in the ECG. The earliest signs were sinus bradycardia, AV dissociation, AV escape rhythmus, prolongation of QT interval and large U wave (U > T, T + U wave). In cases where the differential diagnosis of myocarditis and other heart diseases in adults is difficult, attention should focus in the sickle-like depression ('sagging') of the ST interval, which is a typical sign for diphtheric myocarditis. It occurs even in the presence of pre-existing left-ventricular hypertrophy or bundle branch block. The severest forms of diphtheric myocarditis are complicated by AV and intraventricular conduction disturbances and malignant ventricular tachyarrhythmias.