The effect of coenzyme Q10 in patients with congestive heart failure

Background: Coenzyme Q(10) is commonly used to treat congestive heart failure on the basis of data from several unblinded, subjective studies. Few randomized, blinded, controlled studies have evaluated objective measures of cardiac performance. Objective: To determine the effect of coenzyme Q(10) on peak oxygen consumption, exercise duration, and ejection fraction. Design: Randomized, double-blind, controlled trial. Setting: University and Veterans Affairs hospitals. Patients: 55 patients who had congestive heart failure with New York Heart Association class ill and IV symptoms, ejection fraction less than 40%, and peak oxygen consumption less than 17.0 mL/kg per minute (or <50% of predicted) during standard therapy were randomly assigned. Forty-six patients completed the study. Intervention: Coenzyme Q(10), 200 mg/d, or placebo. Measurements: Left ventricular ejection fraction (measured by radionuclide ventriculography) and peak oxygen consumption and exercise duration (measured by a graded exercise evaluation using the Naughton protocol) with continuous metabolic monitoring. Results: Although the mean (+/-SD) serum concentration of coenzyme Q(10) increased from 0.95 +/- 0.62 mu g/mL to 2.2 +/- 1.2 mu g/mL in patients who received active treatment, ejection fraction, peak oxygen consumption, and exercise duration remained unchanged in both the coenzyme Q(10) and placebo groups. Conclusion: Coenzyme Q(10) does not affect ejection fraction, peak oxygen consumption, or exercise duration in patients with congestive heart failure receiving standard medical therapy.