The effect of coenzyme Q(10) in patients with congestive heart failure

Background: Coenzyme Q(10) is commonly used to treat congestive heart failu re on the basis of data from several unblinded, subjective studies. Few ran domized, blinded, controlled studies have evaluated objective measures of c ardiac performance. Objective: To determine the effect of coenzyme Q(10) on peak oxygen consump tion, 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 predic ted) during standard therapy were randomly assigned. Forty-six patients com pleted 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 (measur ed by a graded exercise evaluation using the Naughton protocol) with contin uous metabolic monitoring. Results: Although the mean (+/-SD) serum concentration of coenzyme Q(10) in creased from 0.95 +/- 0.62 mu g/mL to 2.2 +/- 1.2 mu g/mL in patients who r eceived active treatment, ejection fraction, peak oxygen consumption, and e xercise duration remained unchanged in both the coenzyme Q(10) and placebo groups. Conclusion: Coenzyme Q(10) does not affect ejection fraction, peak oxygen c onsumption, or exercise duration in patients with congestive heart failure receiving standard medical therapy.