Lack of effect of coenzyme Q on left ventricular function in patients withcongestive heart failure

OBJECTIVES This study evaluated the effects of oral therapy with coenzyme Q on echocar diographic and hemodynamic indexes of left ventricular function and on qual ity of life in patients with chronic left ventricular dysfunction. BACKGROUND Coenzyme Q a coenzyme for oxidative phosphorylation and an antioxidant and free radical scavenger. It has been claimed to improve symptoms, quality of life, left ventricular ejection fraction and prognosis in patients with ca rdiac failure. METHODS Thirty patients with ischemic or idiopathic dilated cardiomyopathy and chro nic left ventricular dysfunction (ejection fraction 26 +/- 6%) were randomi zed to a double-blind crossover trial of oral coenzyme Q versus placebo eac h for 3 months. Right heart pressures, cardiac output and echocardiographic left ventricular volumes were measured at baseline and after each treatmen t phase, and quality of life was assessed using the Minnesota "Living With Heart Failure" questionnaire. It was calculated that to demonstrate an incr ease in left ventricular ejection fraction from 25% to 30% with a standard deviation of 5% using 95% confidence intervals with a power of 80% we would require 17 patients. RESULTS Twenty-seven completed both treatment phases. There was no significant diff erence in left ventricular ejection fraction, cardiac volumes or hemodynami c and quality of life indices after treatment with coenzyme Q placebo, alth ough plasma coenzyme Q levels increased from 903 +/- 345 nmol/l(-1) to 2,02 9 +/- 856 nmol/l(-1). CONCLUSIONS Inpatients with left ventricular dysfunction, treatment for three months wi th oral coenzyme Q failed to improve resting left ventricular systolic func tion or quality of life despite an increase in plasma levels of coenzyme Q to more than twice basal values. (C) 1999 by the American College of Cardio logy.