Thirteen RCTs (395 patients) were included in the review. They achieved between four and seven points on the nine point quality score, and study length ranged from four to 28 weeks. Studies were published between 1985 and 2005 and were conducted in seven different countries.
CoQ10 supplementation was associated with a statistically significant increase in ejection fraction of 3.67% (95% CI 1.60% to 5.74%; 13 comparisons; Ι²=67.5). Subgroup analysis indicated this remained significant in crossover trials, trials 12 weeks or less duration, studies published before 1994, doses ≤100mg or less and in patients with less severe congestive heart failure. The post hoc subgroup analysis found the net change in ejection fraction to be statistically significant in patients with less severe congestive heart failure (baseline ejection fraction 30% or below), but not those with more severe disease.
Pooled net change in NYHA functional class was not statistically significant (-0.3 95% CI -0.66 to 0.06; four comparisons; Ι²=80.5%).
Sensitivity analyses did not alter the results and there was no evidence of publication bias.