Prophylaxis to Reduce Postoperative Atrial Fibrillation in Cardiac Surgery

Atrial fibrillation is a common complication of cardiac surgery which is associated with
increased morbidity, length of stay and cost. Efforts to mitigate this problem with beta
blockers and amiodarone have been met with limited success. Observational data suggests that
prophylactic amiodarone has been helpful in decreasing the incidence of AF as well as
increasing its ease of management. The opportunity to use ascorbic acid for AF prophylaxis is
attractive because of its low side effect profile, wide acceptance and low cost.

We have designed a prospective, randomized, controlled trial using a 2 X 2 factorial design
to determine whether prophylactic ascorbic acid alone, ascorbic acid with amiodarone, or
amiodarone alone, when given along with beta blockers will decrease the incidence of
postoperative AF in adult cardiac surgery in all comers as compared with beta blockers alone.

Patients will be randomized into four groups, A, B, C, and D. All groups will receive beta
blockers, Group A will receive beta blockers, ascorbic acid, and amiodarone, Group B will
receive ascorbic acid and Beta blockers, Group C will receive amiodarone and beta blockers
and Group D will receive only beta blockers.

Success of randomization will be assessed by comparing treatment groups with respect to
baseline characteristics, using t-tests or their nonparametric equivalent (as appropriate)
for continuous variables and chisquare tests or Fisher's exact tests for categorical
variables. The primary hypotheses of the effects of ascorbic acid and amiodarone on incidence
of atrial fibrillation will be tested using chisquare tests for differences in proportions.
No adjustment will be made for multiple comparisons since both hypotheses are pre-specified.
We will use exploratory analyses including stratification to assess for the possibility of
effect modification between ascorbic acid and amiodarone. If an interaction is suggested by
these analyses, we will use logistic regression with a cross-product term as a formal
statistical test for interaction.

Inclusion Criteria:

- adults (18 years of age or older)

- all comers for elective or urgent open heart surgery ( CABG, Valve repair or
replacement, Combined CABG/Valves, CABG/other, Other)

Exclusion Criteria:

- patients who refuse to participate

- patients with a history of atrial fibrillation or atrial flutter

- pediatric patients (under 18 years of age)

- Emergency surgery

- patients with contraindications to study medications

- patients with untreated thyroid disease, hepatic failure, pregnancy