NEW YORK (Reuters Health) Dec 29 - Oral coenzyme Q10 improves functional capacity, endothelial function, and left ventricular contractility in patients with chronic heart failure, according to a study in the November issue of the European Heart Journal. "Coenzyme Q10 (CoQ10), first isolated from beef heart mitochondria, is an essential component of the mitochondrial respiratory chain, and also has antioxidant properties," Dr. Romualdo Belardinelli, of Lancisi Heart Institute, Italy, and colleagues write. "However, its role in chronic heart failure (CHF) is not well defined." The study included 23 patients (mean age 59 years) with NYHA class II or III CHF secondary to ischemic heart disease (ejection fraction 37%). Patients were assigned to 4 weeks each of the following: oral CoQ10 (100 mg tid), CoQ10 plus supervised ET, (60% of peak VO2, 5 times/wk), placebo, and placebo plus ET. Of the 23 patients, 21 completed the study. No side effects were attributed to CoQ10. Supplementation with CoQ10 led to a four-fold increase in plasma CoQ10 level (from 0.82 mcg/mL to 3.64 mcg/mL, p < 0.0001). A significant decrease in plasma levels of uric acid (-3%, p < 0.0001) and a significant increase in HDL (+3%, p = 0.0588) were observed with CoQ10 supplementation. No significant changes in total cholesterol. LDL-C, triglycerides, and vitamin E levels were observed. CoQ10 treatment significantly improved peak VO2 (+9%, p = 0.0001). "Systolic wall thickening score index (SWTI) had similar improvements as EF both at rest and at peak dobutamine (-9% and -12%, respectively; p < 0.0001)," Dr. Belardinelli's team writes. "These improvements were related to changes in regional contractility." Patients treated with CoQ10 had significant improvements in the endothelium-dependent relaxation (+38%, p = 0.0021). Combining ET with oral CoQ10 was linked to more marked improvements in all parameters. "Oral CoQ10 improves functional capacity, endothelial function, and left ventricular contractility in CHF without any side effects," the authors conclude. Eur Heart J 2006;27:2675-2681.