Context Atrial fibrillation is a common, but potentially preventable, complication
following coronary artery bypass graft (CABG) surgery.
Objectives To assess the nature and consequences of atrial fibrillation after CABG
surgery and to develop a comprehensive risk index that can better identify
patients at risk for atrial fibrillation.
Design, Setting, and Participants Prospective observational study of 4657 patients undergoing CABG surgery
between November 1996 and June 2000 at 70 centers located within 17 countries,
selected using a systematic sampling technique. From a derivation cohort of
3093 patients, associations between predictor variables and postoperative
atrial fibrillation were identified to develop a risk model, which was assessed
in a validation cohort of 1564 patients.
Main Outcome Measure New-onset atrial fibrillation after CABG surgery.
Results A total of 1503 patients (32.3%) developed atrial fibrillation after
CABG surgery. Postoperative atrial fibrillation was associated with subsequent
greater resource use as well as with cognitive changes, renal dysfunction,
and infection. Among patients in the derivation cohort, risk factors associated
with atrial fibrillation were advanced age (odds ratio [OR] for 10-year increase,
1.75; 95% confidence interval [CI], 1.59-1.93); history of atrial fibrillation
(OR, 2.11; 95% CI, 1.57-2.85) or chronic obstructive pulmonary disease (OR,
1.43; 95% CI, 1.09-1.87); valve surgery (OR, 1.74; 95% CI, 1.31-2.32); and
postoperative withdrawal of a β-blocker (OR, 1.91; 95% CI, 1.52-2.40)
or an angiotensin-converting enzyme (ACE) inhibitor (OR 1.69; 95% CI, 1.38-2.08).
Conversely, reduced risk was associated with postoperative administration
of β-blockers (OR, 0.32; 95% CI, 0.22-0.46), ACE inhibitors (OR, 0.62;
95% CI, 0.48-0.79), potassium supplementation (OR, 0.53; 95% CI, 0.42-0.68),
and nonsteroidal anti-inflammatory drugs (OR, 0.49; 95% CI, 0.40-0.60). The
resulting multivariable risk index had adequate discriminative power with
an area under the receiver operating characteristic (ROC) curve of 0.77 in
the validation sample. Forty-three percent (640/1503) of patients who had
atrial fibrillation after CABG surgery experienced more than 1 episode of
atrial fibrillation. Predictors of recurrent atrial fibrillation included
older age, history of congestive heart failure, left ventricular hypertrophy,
aortic atherosclerosis, bicaval venous cannulation, withdrawal of ACE inhibitor
or β-blocker therapy, and use of amiodarone or digoxin (area under the
ROC curve of 0.66). Patients with recurrent atrial fibrillation had longer
hospital stays and experienced greater infectious, renal, and neurological
complications than those with a single episode.
Conclusions We have developed and validated models predicting the occurrence of
atrial fibrillation after CABG surgery based on an analysis of a large multicenter
international cohort. Our findings suggest that treatment with β-blockers,
ACE inhibitors, and/or nonsteroidal anti-inflammatory drugs may offer protection.
Atrial fibrillation after CABG surgery is associated with important complications.