The Effect of Coenzyme Q₁₀ in Patients with Congestive Heart Failure

BACKGROUND: Coenzyme Q10 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 Q10 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 III 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 Q10, 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 Q10 increased from 0.95+/-0.62 microg/mL to 2.2+/-1.2 microg/mL in patients who received active treatment, ejection fraction, peak oxygen consumption, and exercise duration remained unchanged in both the coenzyme Q10 and placebo groups. CONCLUSION: Coenzyme Q10 does not affect ejection fraction, peak oxygen consumption, or exercise duration in patients with congestive heart failure receiving standard medical therapy.