Natural history of dilated cardiomyopathy: from asymptomatic left ventricular dysfunction to heart failure--a subgroup analysis from the Trieste Cardiomyopathy Registry.

BACKGROUND: Few data are available in the literature regarding the characteristics and prognosis of asymptomatic patients with idiopathic dilated cardiomyopathy (DCM). AIM: To determine the frequency with which patients affected by DCM are diagnosed in the asymptomatic state as well as to evaluate the natural history of such patients and the factors influencing their outcome. Moreover, we sought to compare the outcome of asymptomatic patients with that of patients with signs of overt heart failure at the time of first evaluation. METHODS AND RESULTS: We analyzed the data of 747 patients with DCM enlisted in the Heart Muscle Disease Registry of Trieste from 1978 to 2007. We divided our population into four groups; group 1 comprised 118 asymptomatic [New York Heart Association (NYHA) I] patients without a history of congestive symptoms (16%), group 2 comprised 102 asymptomatic (NYHA I) patients (14%) with a positive anamnesis for heart failure stabilized in medical therapy, group 3 comprised 327 patients (44%) with signs of mild heart failure (NYHA II) and group 4 comprised 200 patients (26%) in NYHA III-IV. During the follow-up of 112+/-63 months, 46 (21%) of 220 asymptomatic patients with DCM died or underwent heart transplantation. By Cox proportional model, left ventricular ejection fraction of 30% or less was a unique independent predictor either for death/heart transplantation (hazard ratio 3.15, 95% confidence interval 1.5-6.7, P=0.003) or for sudden death/major ventricular arrhythmias (hazard ratio 3.9, 95% confidence interval 1.7-9.3, P=0.002). Patients from group 1 had a trend for a better outcome with respect to those from group 2 (P=0.06). In comparison with the asymptomatic patients, those with signs of overt heart failure at baseline had a worse prognosis. CONCLUSION: The proportion of asymptomatic patients with DCM at the moment of first evaluation at our center is significant (30%). Among them, those without a previous history of heart failure had a less advanced disease and a trend for a better long-term outcome on optimal medical treatment. Therefore, early diagnosis may offer better long-term quality of life and even better survival. Further studies on larger populations are indicated.