ACE inhibitors in mild heart failure: first-line or second-line therapy?

Despite the successful therapeutic applications of angiotensin-converting enzyme (ACE) inhibitors to date, knowledge of how they work and guidelines for their use are still incomplete. On their role as monotherapy in congestive heart failure, we have scarce and conflicting data. Nor is there a clear answer to the question, when should an ACE inhibitor be started in a patient with heart failure? In patients with severe heart failure, the addition of an ACE inhibitor to a diuretic regimen has been shown to improve prognosis. In patients with mild heart failure, a benefit has not been demonstrated. In one preliminary report, monotherapy with the ACE inhibitor quinapril was shown to improve exercise time and functional class in patients with mild heart failure compared to placebo.