New Guidelines Tackle Postsurgical Atrial Fib


β-Blockers should be the first choice to control both rhythm and rate in patients experiencing atrial fibrillation after cardiac surgery; the drug class is also useful for preventing postoperative atrial fibrillation, according to new clinical practice guidelines issued by the American College of Chest Physicians.

The drugs' value stems from their antiadrenergic effect, said Peter McKeown, M.B., a member of the panel that authored the guidelines. “This counteracts the proadrenergic state patients experience after surgery, which can lead to atrial fibrillation,” he said. Bolstering the recommendation is the fact that many cardiac surgery patients are already on the drugs, which should not be discontinued before surgery.

“We should be putting them on β-blockers if they're not already on them, and keeping them on if they are,” Dr. McKeown said in an interview.

The panel, which included members of ACCP, the American College of Cardiology, the American College of Surgeons, the Society of Thoracic Surgeons, and the Society of Cardiovascular Anesthesiologists, also concluded that digoxin is contraindicated in these patients because it heightens postoperative adrenergic tone (Chest 2005;128:S1–S64).

Amiodarone was recommended for controlling rhythm in patients with postoperative AF and depressed left ventricular function, added Dr. McKeown of Duke University, Durham, N.C.

“A lot of the other drugs you hear about were not recommended because of their potential for rhythm disturbances, or because they are not suitable for patients with coronary artery disease,” he said.

The new guidelines were deemed necessary because existing guidelines don't focus on atrial fibrillation (AF) in postcardiac surgery patients, said Eric Prystowsky, M.D., a panel member and director of the Clinical Electrophysiology Laboratory at St. Vincent Hospital, Indianapolis.

“The AF that occurs after cardiac surgery is really a unique problem that should be looked at differently than other AF issues,” he said in an interview. “It's a situation that has a temporal relationship to a very specific event, and should not be viewed as an ongoing event.”

Because of its acute nature and its common occurrence—up to 60% of cardiac surgery patients experience it—many patients leave the hospital either over- or undertreated, said Dr. Prystowsky, who also coauthored the 2001 American College of Cardiology/American Heart Association/European Society of Cardiology Guidelines for the Management of Patients With Atrial Fibrillation (J. Am. Coll. Cardiol. 2001;38:1231–66).

“If these patients fit a high-risk pattern for stroke, and many cardiac surgery patients do, then they are at a significantly increased risk if they develop AF. Many of them go home inappropriately anticoagulated. But it's not necessary for the rest of their lives. After they get back into normal rhythm, they can go back to their previous treatment regimen.”

The obsession with immediate restoration of normal heart rhythm has led to overtreatment, he added. “People are overaggressively focused on putting the rhythm back to normal acutely.”

“You don't have to give all kinds of drugs with potential toxicity. We have to remember this is an acute situation. It's perfectly acceptable to control the rate, make sure they're appropriately anticoagulated, and then let them regroup. The majority are back in normal rhythm by their 6-week checkup,” explained Dr. Prystowsky.

In constructing its recommendations, the panel conducted a comprehensive literature review that included 128 controlled trials; the evidence from each trial was graded, as were each of the subsequent recommendations.

“We looked for studies that could give answers to four goals for these patients,” Dr. McKeown said: “controlling ventricular response rate in AF, preventing thromboembolism, converting to normal sinus rhythm, and prophylaxis to prevent AF in this population.”

The panel found conflicting data on anticoagulation therapy for postoperative AF; therefore its recommendations in this area were based on expert opinion. However, the panel did recommend anticoagulation therapy in optimally selected patients with chronic AF and in those patients in whom it is likely that AF will continue.

For patients with chronic AF, the panel recommended postoperative warfarin, giving the recommendation an “A” grade, and saying the net benefit was substantial. For those with postoperative AF, the panel recommended postoperative heparin. The recommendation received a grade of “C,” with an intermediate net benefit.

The panel found no strong evidence as to duration of anticoagulation but said physicians should take into consideration the self-limiting nature of postoperative AF.

Studies comparing rates of atrial fibrillation in off-pump vs. on-pump coronary artery bypass graft procedures yielded conflicting results, the panel said. Therefore, it could not recommend off-pump procedures as a method of reducing postoperative AF.

Biatrial pacing after surgery was found to be effective in reducing the incidence of AF, and received a “B” grade, although evidence shows that the net benefit is probably small. Inconclusive evidence precluded the recommendation of isolated left or right atrial pacing.


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