Postoperative atrial fibrillation: an old problem crying for new solutions.

I n this issue of the Journal, Mueller and colleagues1 report on their experience with postoperative atrial arrhythmias in a series of 183 patients who underwent isolated single coronary artery bypass grafting (CABG) with the left internal thoracic artery placed to the left anterior descending coronary artery. The authors observed that the prevalence of postoperative atrial arrhythmias was similar, at approximately 18% to 22%, for patients having conventional CABG and for those having beating-heart operations. With the development and growing acceptance of technologies that facilitate less invasive approaches for CABG, several recent, but conflicting, reports have been published on the frequency of this complication.2-12 In light of an appreciable change in the current practice of CABG, and the conflicting information regarding postoperative atrial fibrillation, it would be useful to reflect on what is presently known about this complication and the most appropriate direction for our future efforts in this area. Large-scale longitudinal studies have demonstrated that atrial fibrillation is the most common arrhythmia in the general population.13,14 The prevalence of this arrhythmia increases with age, with a prevalence of less than 1% at age 50 but more than 9% to 10% at age 80.13 Other risk factors in the general population include congestive heart failure, valvular heart disease, hypertension, diabetes, and a history of myocardial infarction. Given these predisposing factors, it is not surprising that this arrhythmia is a common complication in the adult population having cardiac surgery. Atrial arrhythmias have been recognized as a common postoperative complication since the earliest days of CABG. These arrhythmias include atrial fibrillation, atrial flutter, and paroxysmal atrial tachycardia. Clinical studies have reported a prevalence of 25% to 40% among patients undergoing CABG, with a peak incidence occurring between the second and fourth days after the operation.15 This rate is even higher for patients undergoing valve replacement, either alone or in combination with CABG. For most patients, postoperative atrial arrhythmias are a benign complication, without significant morbidity. Nonetheless, there is ample evidence that they are associated with adverse outcomes, including patient discomfort or anxiety, the need for extra medications or treatments, the possibility of thromboembolic complications, and both increased hospital length of stay and hospital costs.16-18 There are few data regarding the post-hospital discharge course of patients with this complication, but it is generally believed that the risk of this arrhythmia decreases substantially within the first month after surgery. It is important to remember that in an era of early hospital discharge, often on the third or fourth postoperative day, these arrhythmias may occur after discharge and patients should be counseled appropriately. The treatment of patients with postoperative atrial arrhythmias has not been standardized despite many years of clinical experience and investigation. Directcurrent cardioversion is highly effective for restoring sinus rhythm in most patients, but this procedure is typically reserved for patients with hemodynamic instability. In clinical practice, most patients are treated medically for their arrhythmias. There are two goals of pharmacologic therapy: (1) control of the heart rate and (2) conversion to a sinus rhythm. Medications such as diltiazem, -blockers, or digoxin can be used effectively to control the heart rate, and drugs such as sotalol, amiodarone, ibutilide, From the Division of Cardiothoracic Surgery, Washington University School of Medicine, St Louis, Mo.