Background: The natural history of idiopathic dilated cardiomyopathy (IDC), once a disease with a dire prognosis, is thought to be changing. Aim of this study was to describe the clinical characteristics, long term course and prognostic factors of IDC patients followed up prospectively since the late eighties.
Methods: Patients with a diagnosis of IDC confirmed by normal coronary angiography, non specific endomyocardial biopsy findings and a left ventricular ejection fraction below 50% were consecutively enrolled in a multicenter registry and followed up at 6-months intervals.
Results: From January 1986 till January 1994, 441 IDC patients with a mean age of 43 +/- 13 years (range 8-68) entered the registry. Thirty per cent of patients were women and 8% had familial dilated cardiomyopathy. NYHA class was I-II in 77% and 35% of patients were asymptomatic at the time of diagnosis. Treatment included digitalis in 235 patients (53%), diuretics in 239 (54%), angiotensin converting enzyme inhibitors in 269 (61%), betablockers in 108 (24%). Chronic atrial fibrillation was detected in 10% of patients and left bundle branch block in 24%. Mean cardiothoracic ratio was 0.54 +/- 0.06. Mean left ventricular end diastolic dimension was 38 +/- 6 mm/m2; 48% of patients had minimal or mild left ventricular dilatation. Mean left ventricular ejection fraction was 30 +/- 10%. At Holter monitoring 67% of cases had complex ventricular arrhythmias, 37% had ventricular tachycardia and 4% had advanced atrioventricular block. Mean exercise stress test duration was 9 +/- 4 minutes. After a mean follow up of 31 +/- 24 months, 337 patients were alive without transplantation and 5 were lost to follow up; 60 patients (14%) had died of cardiac causes, namely heart failure (6%), sudden death (7%) and pulmonary embolism (< 1%) and 30 had been transplanted (7%), while 4 had died of unclear causes. Survival and transplant-free survival were 94% and 90% at 2 years and 82 and 76% at 5 years, respectively. At multivariate analysis pulmonary capillary wedge pressure (p = 0.0001, odds ratio, for values > 15 mm Hg, 2.05) and betablocker treatment (p = 0.002, odds ratio 0.26) were independent predictors of survival.
Conclusions: In this large, multicenter prospective study, prognosis of IDC in the eighties appears to be improved. Early diagnosis, together with improved medical treatment, probably bears a causal relation to these changes.