No funding obtained to support patient recruitment

The purpose of this study is to determine if vitamin C decreases the chance of developing atrial fibrillation, a type of arrhythmia or irregular heartbeat, following cardiac surgery. This irregular heartbeat is a common occurrence following cardiac surgery, and occurs in about one third of patients. It poses extra risks to people who develop it. Our hypothesis is that Vitamin C will decrease the incidence of postoperative atrial fibrillation.

The development of atrial fibrillation (AF) following cardiac surgery is relatively common, occurring in approximately 25-60% of patients. Coronary artery bypass graft surgery (CABG) carries the lowest risk of AF development, with an incidence of approximately 25-30%, followed by cardiac valve and combined CABG/cardiac valve surgeries, with incidences up to 60%. AF development in patients undergoing cardiac procedures has been linked to increases in postoperative morbidity and mortality, including an increase in readmission to the ICU, stroke, reintubation, and 30-day and 6-month mortality. Patients who develop AF have also been shown to experience longer hospital stays, both in the ICU and overall.

While some other medications have been shown to decrease the risk of AF development, the use of beta-blockers peri- and postoperatively have shown the most promise, and are the standard of care for patients undergoing CABG surgery. However, patients experiencing AF have been shown to experience cardiac production of peroxynitrite, corresponding to a hypothesis that AF occurs through oxidative stress. Due to this correlation, supplementation of ascorbate has been proposed as a treatment to reduce the risk of AF development following cardiac surgery. Ascorbate is a potent peroxynitrite antagonist, and may therefore reduce oxidative stress and AF development following cardiac surgery. This trial aims to assess the efficacy of ascorbic acid in reducing the incidence of postoperative AF in patients undergoing elective or urgent CABG surgery, cardiac valve surgery, or a combination of the two. Our hypothesis is that ascorbic acid will decrease the incidence of postoperative AF development.

Inclusion Criteria:

• Adults 50 years of age or older
• Undergoing elective or urgent coronary artery bypass graft surgery, valve surgery, or a combination of the two

Exclusion Criteria:

• Prior cardiac surgery
• History of atrial fibrillation
• Permanent or temporary pace maker
• Currently taking digoxin or Vaughan Williams Class I or III antiarrhythmic medications
• Known hyperoxaluria
• History of renal calculi
• History of allergic or hypersensitivity reaction to ascorbic acid products
• Currently taking 1 g or more of ascorbic acid supplementation daily