N-acetylcysteine helps prevent post-operative AF
ISPARTA, TURKEY. N-acetylcysteine (NAC) has anti-inflammatory properties and is the precursor of glutathione, the body's main indigenous antioxidant. It is effective in counteracting the effects of acetaminophen (Tylenol, Paracetamol) poisoning and is protective against kidney damage caused by exposure to x-ray dyes (contrast media). Turkish researchers now report that NAC is also highly effective in preventing post-operative atrial fibrillation (AF). The development of AF following cardiac valve surgery and coronary artery bypass surgery is quite common affecting between 10% and 65% of patients. Considering that well over 500,000 bypass operations (half of which are likely unnecessary) are performed each year in the US alone, post-operative AF is clearly a major problem.

The Turkish researchers reasoned that since cardiac surgery is accompanied by inflammation, substantially increased oxidative stress, and a loss of glutathione, it would perhaps be beneficial to pre- and post-treat patients with a potent antioxidant and glutathione precursor such as NAC. Their randomized, double-blind, placebo-controlled clinical trial involved 115 patients 107 of which underwent bypass surgery alone, while the remaining 8 underwent valve surgery with or without accompanying bypass surgery.

Half of the study participants received an intravenous infusion of NAC one hour prior to their procedure followed by an infusion for 48 hours after the procedure. The amount of NAC infused prior to surgery was 50 mg/kg (3500 mg for a person weighing 70 kg – 154 lbs), while the amount infused during the 2 days following the procedure was 50 mg/kg per day. The other half of the group just received a standard saline infusion. All patients were monitored with 12-lead electrocardiography. No side effects of NAC administration were observed.

During follow-up 21.1% of patients in the placebo (saline infusion) group developed AF as compared to only 5.2% in the NAC-treated group – a 4-fold reduction in risk. All afib episodes converted to sinus rhythm either spontaneously or with the use of amiodarone. The researchers conclude that pre- and post-treatment with NAC substantially reduces the risk of post-operative AF and speculate that NAC therapy may be of value in AF patients.

Ozaydin, M, et al. N-acetylcysteine for the prevention of postoperative atrial fibrillation. European Heart Journal, Vol. 29, 2008, pp. 625-31

Editor's comment: There is little question that bypass surgery is a potent "recruiting ground" for afib patients. Whether or not these patients go on to have subsequent episodes is not clear, but certainly, anything that will help prevent that first episode is most welcome. Could regular supplementation with NAC help prevent future episodes? I am not aware of any evidence to this effect, but it certainly is an intriguing possibility. It is, unfortunately, not clear from the article whether the NAC was infused in a saline solution or in an aqueous solution. If indeed it was infused in the aqueous form (no salt), then it is possible that the observed benefits of NAC were at least partly due to the lack of salt (sodium chloride) in the infusion. Somehow, it does not seem like a great idea to infuse a salt solution after the patient has suffered the significant potassium loss always accompanying cardiac surgery.