ACCP guidelines focus on post-operative atrial fibrillation

Beta-blockers are the top choice for prevention of postoperative atrial fibrillation (AF) and control of ventricular rate, according to the first evidence-based clinical guidelines for the prevention and management of postoperative AF after cardiac surgery, published recently by the American College of Chest Physicians (ACCP).

The guidelines recommend beta-blockers over calcium-channel blockers-a standard therapy for chronic AF-for general prevention of postoperative AF and control of ventricular rate. AF, or irregular heartbeat, is a common condition that occurs increasingly with age and is a frequent complication of cardiac surgery. More than one-third of patients are commonly affected.

"Beta-blockers were found to be the single most effective therapeutic agent for both the prevention and management of AF after cardiac surgery," said guidelines co-chair Peter P. McKeown, MBBS, MPH, MPA, FCCP, Veterans Affairs Medical Center, Asheville, N.C. "In the studies reviewed for this set of guidelines, the evidence supporting beta-blockers was much stronger. Calcium-channel blockers may have a secondary role in some patients with regard to rate control."

"Previous guidelines have focused on the management of chronic AF, but ours are the first to address AF associated with cardiac surgery," said McKeown.

The guidelines highlight recommendations that center on the chief issues that arise in managing patients with postoperative AF, including overall prevention, control of ventricular response rate, restoration of normal sinus rhythm, and prevention of thromboembolism and the role of anticoagulation. They offer specific recommendations on cardiac pacing, anticoagulation therapy, pharmaceutical prophylaxis, intraoperative interventions, and pharmacologic control of ventricular rate and rhythm.

"Clinical pharmacists can have a critical role to play in helping the surgeon manage and prevent postoperative AF," said McKeown. "Many of the drugs we use may have significant side effects and interactions. The clinical pharmacist can play a support and resource role in educating the patient and the physician, a monitoring role to look for potential drug interactions and dosing adjustments, and a role in clinical trials and research studies."

The guidelines also recommend against the routine use of magnesium and digitalis for the prevention of postoperative AF. Amiodarone may be considered for patients for whom beta-blockers are contraindicated and as therapy for postoperative sinus rhythm control. Atrial pacing, the use of a pacemaker to control arrhythmia, was found to reduce the incidence of AF after cardiac surgery; however, biatrial pacing is recommended to reduce the occurrence of AF during intraoperative procedures. In regard to the prevention of thromboembolism, the guidelines recommend cautious anticoagulation therapy for patients in whom AF has persisted for more than 48 hours.

"The issue of anticoagulation in AF following cardiac surgery is an important one," said McKeown. "Nearly 30% of patients have AF after coronary artery bypass procedures and an even higher percentage following valve procedures. Current recommendations are to consider anticoagulation for at least one month for postoperative cardiac surgery patients who are in AF for more than 48 hours. If they still have AF after a month, then chronic anticoagulation may be required unless they have successful cardioversion."

In addition to the currently available beta-blockers, the guidelines indicate that new drugs may become available in the near future to selectively treat and prevent AF. Newer class III antiarrhythmic agents likely to find clinical application include azimilide (Procter & Gamble), a type III potassium-channel blocker; and dronedarone (Sanofi-Aventis), a drug similar to amiodarone that is undergoing clinical trials.

For a copy of the ACCP Guidelines for the Prevention and Management of Postoperative Atrial Fibrillation After Cardiac Surgery, visit the ACCP Web site at http://www.chestnet.org/.