Heart failure (HF) is a progressive process and the objective of treatment should be to prevent progression. Treatment should begin at the stage of asymptomatic left ventricular dysfunction (LVD), not only to reduce mortality but also to preserve exercise capacity and quality of life. To prevent clinical progression in patients with asymptomatic LVD or HF, left ventricular remodelling and dilatation must be prevented. The SOLVD prevention trial - the only clinical trial on the prevention of HF - showed that ACE inhibition significantly reduced the development of HF, but did not significantly reduce mortality. Plasma norepinephrine is elevated in patients with asymptomatic LVD, is further elevated in patients with overt HF, and is correlated with increased mortality. Inhibition of the sympathetic nervous system by administration of β-blocking agents is therefore a logical treatment for patients with HF or asymptomatic LVD. Clinical trials have shown that β-blocking agents increase left ventricular ejection fraction and reduce left ventricular dimensions in patients with HF, indicating regression of left ventricular remodelling. Almost all the patients in these studies were receiving an ACE inhibitor as part of their background medication, therefore the relative efficacy of β-blocking agents and ACE inhibitors in the regression of remodelling is not known. CARMEN, a double-blind, randomised, parallel group study of carvedilol versus enalapril versus carvedilol + enalapril in 450 patients with mild HF, will provide this information.