Effect of Alpha-Lipoic Acid Supplementation on the Incidence of Postoperative Atrial Fibrillation in Cardiac Surgery Patients

Investigators computed on the basis of findings from a prior study found the incidence of POAF after cardiac surgery of about 25% . Assuming a slightly lower alpha-lipoic acid' effect to previous study. If the true relative risk of AF for experimental subjects relative to controls is 0.5 , with α equivalent to 0.5 and power (1 - β) is 0.8, the estimated sample size is 152 experimental subjects and 152 control subjects in order to be able to reject the null hypothesis that this relative risk equals 1 with probability (power) of 0.8. investigators used the uncorrected chi-squared statistics to evaluate this null hypothesis. STATA software version and taking into account a possible dropout of 15%, the total sample size was: 304 + 0.15 (304) × 2 = 350 subjects of which there will be 175 controls and 175 experimental subjects %, assuming an enrolment ratio of 1:1.