In order to study the etiology, the clinical course and the prognosis of patients with DCM, clinical, morphological (endomyocardial catheter biopsy), angiographic and hemodynamic data of patients with DCM were studied. The total number of patients was 396. In 258 patients definite DCM was diagnosed, in 138 patients DCM was suspected, e.g., because of an additional history of alcoholism.
Etiology: In no case acute subacute or chronic myocarditis was found in myocardial biopsies (n = 114) and at autopsy (n = 18). However, from the history strong evidence was obtained for DCM being the late stage of diphtheric heart disease predominantly among patients with complete left bundle branch block. As far as the alcoholic etiology is concerned, the only significant difference between DCM and alcoholic heart disease was a higher proportion of women among patients with DCM (28% and 5%, resp.). Clinical course and prognosis: 221 patients were studied prospectively (mean follow-up time 3.1 +/- 2.3 years), 44% of patients died or deteriorated. However, in patients with normal cardiothoracic ratio this rate amounted only to 12%. The mean annual mortality rate was 9.8% and varied significantly in relation to different subsets of patients from 0% to 17%. A bad prognosis was significantly indicated by young age, high cardiothoracic ratio, pronounced elevation of enddiastolic volume index and of left ventricular enddiastolic pressure at rest and of mean pulmonary artery pressure at exercise, by severe morphologic changes of myocardial biopsies, severe ventricular arrhythmias, the absence of transient abnormal elevation of arterial blood pressure during follow up, of complete left bundle branch block and of a positive history of diphtheria. However, the wide scatter of data diminished the significance of them for the definite prognostic evaluation of individual case. The cumulative survival curves of patients with a history of alcohol abuse did not differ from that of patients with DCM. The data demonstrate that DCM in patients with the history of diphtheria together with left bundle branch block is possible caused by an inflammatory process. According to the analysis of the clinical course and the prognosis, DCM is one of the most severe heart disease. However, in different subsets of patients, the clinical course may be stable for long time and even normal longevity cannot be excluded.