Executive summary : American College of Chest Physicians guidelines for the prevention and management of postoperative atrial fibrillation after cardiac surgery

Abbreviations: ACCP = American College of Chest Physicians; EPC = Evidence-Based Practice Center; RCT = randomized controlled trial

This evidence-based clinical practice guideline provides a summary of the most current literature on the management of postoperative atrial fibrillation following cardiac surgery, and provides recommendations for the prevention and management of this condition based on the reported scientific data. The expert panel that developed these guidelines relied on results from randomized controlled trials (RCTs) that were identified through specified criteria related to predefined research questions. These questions focused on the following central areas:

1. Controlling the ventricular response rate in patients with atrial fibrillation after they had undergone cardiac surgery;

2. Preventing thromboembolism and the role of anticoagulation therapy in the surgical patient;

3. Converting the heart beat to normal sinus rhythm; and

4. Using pharmacologic and surgical prophylaxis to prevent postoperative atrial fibrillation.

The multidisciplinary panel developing these evidence-based recommendations consisted of experts in the fields of cardiothoracic surgery, cardiology, anesthesiology, and epidemiology. The panel worked with methodological experts from the Johns Hopkins Evidence-Based Practice Center (EPC) to develop the evidence base for the practice guideline. The American College of Surgeons, The American College of Cardiology, and The Society of Thoracic Surgeons were represented on the panel.

REPORTING THE EVIDENCE

The American College of Chest Physicians (ACCP) worked with the Johns Hopkins EPC to gather and analyze the evidence from published studies. A systematic review of the current literature was conducted based on inclusion criteria and specific research questions defined by the panel and the EPC. Of almost 1,000 articles that were screened, approximately 128 articles met these criteria and were formally reviewed. The selection criteria included adult subjects, English language, and controlled trials. Selected study articles were then scored on the following basis:

1. Representativeness;

2. Bias and confounding; 2 3. Intervention description;

4. Outcomes and follow-up; and

5. Statistical methods and interpretation.

From these criteria, the quality of the evidence was graded as follows:

1. Good: evidence based on good RCTs or metaanalysis;

2. Fair: evidence based on other trials or RCTs with minor flaws;

3. Low: evidence based on nonrandomized, case-control, or other observational studies; and

4. Expert opinion: no studies meeting the criteria for inclusion, so evidence is based on a consensus opinion of a carefully selected panel of experts.

The grading of the strength of the recommendation is based on both the quality of the evidence and the net benefit of the intervention (Table 1), as follows:

* A: Strong recommendation;

* B: Moderate recommendation;

* C: Weak recommendation;

* D: Negative recommendation;

* I: No recommendation possible/inconclusive;

* E/A: Strong recommendation based on expert opinion only;

* E/B: Moderate recommendation based on expert opinion only;

* E/C: Weak recommendation based on expert opinion only; and

* E/D: Negative recommendation based on expert opinion only.

The net benefit to the patient, adjusted for risk, was based on clinical assessment and was classified as follows:

* Substantial;

* Intermediate;

* Small/weak;

* None;

* Conflicting; and

* Negative

The clinical practice guidelines address the wide spectrum of issues related to the prevention and treatment of postoperative atrial fibrillation following cardiac surgery.

Specific recommendations are provided on the topics of cardiac pacing, anticoagulation therapy, the use of pharmaceutical prophylaxis, intraoperative interventions, and pharmacologic control of ventricular rate and rhythm. In addition, these guidelines provide valuable resources in identified areas of the methodological approach used to develop the recommendations as well as for future research.

INTERVENTIONS

Controlling the Ventricular Response Rate in Atrial Fibrillation After Cardiac Surgery

Few RCTs address pharmacologic control of the ventricular response rate to atrial fibrillation or atrial flutter after surgery. However, evidence does support the use of beta-blockers as the first line of therapy in those patients who do not require urgent cardioversion. Nondihydropyridine calcium channel blockers are recommended as second-line agents. Studies showed little efficacy of digoxin and agents with proarrhythmic potential such as dofetilide, or agents that are contraindicated in patients with coronary artery disease such as flecainide and propafenone (Table 2).

Preventing Thromboembolism and the Role of Anticoagulation

There are few data to address issues related to anticoagulation therapy in patients with new-onset atrial fibrillation following cardiac surgery. Several older studies have shown some benefit of this type of therapy; however, the anticoagulation chapter stresses the need to consider this therapy carefully in relation to the often self-limited duration of this atrial fibrillation and the risks of bleeding in the early postoperative period. Anticoagulation therapy recommendations are summarized in Table 3.

Converting to Normal Sinus Rhythm

Nineteen trials were identified on the topic of pharmacologic rhythm control; however, no consistent recommendation was possible in patients not requiring urgent cardioversion. This emphasizes the need to guide pharmacologic intervention based on the individual patient. Amiodarone therapy is recommended in patients with depressed left ventricular function who do not need urgent electrical cardioversion. Sotalol and class 1A antiarrhythmic drugs may be used in patients with coronary artery disease who do not have congestive heart failure. No definitive data exist to guide the decision on the duration of drug use (Table 4).

Prophylaxis to Prevent Postoperative Atrial Fibrillation

Pharmacologic: Several chapters in this clinical practice guideline address issues related to pharmacologic interventions in the management of postoperative atrial fibrillation or atrial flutter. The article on pharmacologic prophylaxis focused on Vaughan-Williams class I, II, and III agents, as well as on other strategies such as the use of digitalis, insulin, alinidine, and dexamethasone (Table 5). The analysis of the data demonstrated the variability in the efficacy of many of these agents in preventing postoperative atrial fibrillation or atrial flutter. A relatively strong recommendation was made for the use of beta-blockers (class II) in patients in whom prophylaxis is indicated. Although therapy with sotalol can be considered, the drug is associated with increased toxicity and, therefore, may not be the optimal preventive strategy.

Amiodarone therapy may be considered in those patients for whom beta-blockers are contraindicated. The routine use of magnesium, digitalis, or calcium channel antagonists is not supported by the current evidence.

Surgical: Surgical prophylaxis was considered under the following two separate sections: (1) the use of pacing postoperatively to prevent atrial fibrillation; and (2) intraoperative interventions other than pacing.

Pacing: Recommendations were made in support of biatrial cardiac pacing to help prevent postoperative atrial fibrillation. Right or left atrial pacing alone is not recommended. Unfortunately, to obtain the full benefit of pacing it needs to be continued for 3 days postoperatively (Table 6).

Intraoperative Interventions

Intraoperative interventions were assessed to see whether they might play a role in the prevention of postoperative atrial fibrillation. There was no strong evidence to suggest that beating heart/off-pump coronary artery bypass graft surgery was associated with a lower rate of postoperative atrial fibrillation (Table 7).