The use of angiotensin converting enzyme (ACE) inhibitors has been shown to significantly decrease rates of morbidity and mortality in patients with congestive heart failure (CHF). Most studies support the use of high-dose ACE inhibitors, but the clinical data indicate that only 25 percent of patients with CHF were receiving full dosages of their ACE inhibitors, despite recent recommendations that high-dose ACE inhibitor therapy should be the goal in CHF treatment. Van Veldhuisen and associates studied the dose-related effects of three dosages of a long-acting ACE inhibitor in patients with mild to moderate CHF.
Patients with mild to moderate CHF (New York Heart Association classes II and III) were enrolled in the 12-week study. All of the patients were stable and were undergoing therapy with digoxin and diuretics. A double-blind, placebo-controlled study was performed, with the treatment groups receiving 2.5, 5 or 10 mg of imidapril. Exercise testing was performed twice at baseline and at weeks 8 and 12 of the study. Plasma neurohormones were measured at rest and at the peak of the exercise test.
The initial results showed that after eight weeks no significant differences were apparent between the various treatment and placebo groups. However, at week 12, the group that was taking 10 mg of imidapril had a significant improvement in exercise time and physical walking capacity. The increasing ACE inhibitor dosage also had a positive impact on plasma neurohormones that followed a linear pattern.
Even though high-dose ACE inhibitor therapy is indicated in the treatment of CHF, clinicians tend to use lower dosages. Inadequate dosing could be a result of concerns about increasing adverse events with higher dosages.
The authors conclude that, despite these concerns, patients showed a significant improvement in functional status with a short course of high-dose ACE inhibitors. They believe that even though this was a short study and further studies are needed to confirm these results, high-dose ACE inhibitors should be used in the treatment of mild to moderate CHF.