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:
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:
* Conflicting; and
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.
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 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).
The panel of experts was convened through the Health and Science Policy Committee of the ACCP to develop a set of clinical practice guidelines for the prevention and management of atrial fibrillation after cardiac surgery, based on the literature available at the time. Although there are a large number of articles related to the topic, there is a paucity of prospective randomized clinical trials, which makes the development of definitive recommendations difficult. The panel has spent a large amount of time and effort trying to maximize the information available without making too many assumptions in the formation of these recommendations. Further research in the area of the prevention and management of postoperative atrial fibrillation after cardiac survey is needed. Developing evidence-based clinical practice guidelines is an evolving process. The recommendations are based on the highest quality of data available at the current time. The panel will regularly monitor new studies on this topic for possible updates.
ACCP GUIDELINE DEVELOPMENT PROCESS
The ACCP finds it imperative to include individuals who are experts in their respective fields on guideline development committees. The recommendations and publications that are the products of these committees will have far-reaching significance that may affect multiple aspects of the practice of chest medicine throughout the world; therefore, it is essential that the ACCP have full disclosure of outside interests from those individuals serving on policy development committees, including liaison representatives from outside organizations. Both real and potential conflicts of interest may actually affect or appear to affect impartial or objective decisions.
Evidence-based medicine is defined as using the best available data from the published literature in conjunction with clinical knowledge and patient preferences to make appropriate decisions regarding patient care. The ACCP evidence-based clinical practice guidelines are developed through an approved, rigorous process that involves conducting a systematic literature review and deriving recommendations based on the data. The guidelines follow formal review and approval processes prior to publication as ACCP policy.
In the ever-changing field of medicine, it is important and necessary to have access to up-to-date information. New studies that may have become available late in the process of guideline development may not be incorporated into this document. Therefore, the reader is encouraged to seek out newer information that might impact the diagnostic and treatment recommendations contained within the guideline. Clinical practice guidelines are developed to enhance the clinician's ability to practice evidence-based medicine and also to provide an opportunity for the busy clinician to receive the latest evidence on a particular topic. The information provided in the guideline should be used in conjunction with clinical judgment. Although the guideline provides recommendations that are based on evidence from studies involving various populations, the recommendations may not apply to every individual patient. It is important for the physician to take into consideration the role of patient preferences and the availability of local resources.
The ACCP is sensitive to concerns that nationally and/or internationally developed guidelines are not always applicable in local settings. Further, guideline recommendations are just that: recommendations, not dictates. In treating patients, individual circumstances, preferences, and resources play a role in the course of treatment at every decision level. Although the science behind evidence-based medicine is rigorous, there are always exceptions. The recommendations are intended to guide health-care decisions. These recommendations can be adapted to be applicable at various levels.
** From the Department of Surgery, Asheville Veterans Affairs Medical Center (Dr. McKeown) Asheville, NC; and the Department of Internal Medicine (Dr. Gutterman), Medical College of Wisconsin, Milwaukee, WI.
Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal. org/misc/reprints.shtml).
Correspondence to: Peter P. McKeown, MBBS, MPH, MPA, FCCP, Department of Surgery, Veterans Affairs Medical Center, 1100 Tunnel Rd, Asheville, NC 26805; e-mail: peter.mckeown@ med.va.gov
COPYRIGHT 2005 American College of Chest Physicians
COPYRIGHT 2005 Gale Group