(Chest. 2005;128:17S-23S.)
© 2005
American College of Chest Physicians
Methodological Approach*
American College of Chest Physicians Guidelines for the Prevention and Management of Postoperative Atrial Fibrillation After Cardiac Surgery
Lee A. Fleisher, MD;
Eric B. Bass, MD, MPH and
Peter McKeown, MD, FCCP
* From the Department of Anesthesia (Dr. Fleisher), University of Pennsylvania Health System, Philadelphia, PA; Johns Hopkins University School of Medicine (Dr. Bass), Baltimore, MD; and Asheville Veterans Affairs Medical Center (Dr. McKeown), Asheville, NC.
Correspondence to: Lee A. Fleisher, MD, University of Pennsylvania Health System, 3400 Spruce Street, Philadelphia, PA 19104; e-mail: Fleishel{at}uphs.upenn.edu
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Abstract
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Atrial fibrillation remains a common and challenging problem following cardiac surgery. The American College of Chest Physicians, through the Health and Science Policy Committee, established a panel to develop a set of clinical practice guidelines for the management or prophylaxis of atrial fibrillation or flutter in patients undergoing coronary artery bypass surgery. The panel based its guidelines on a systematic review of the literature that included a computerized search of PubMed and CENTRAL, the Cochrane Collaboration database, as well as a search of selected journals and references in key articles. Studies were eligible for review if they were controlled trials. Paired reviewers assessed the quality of each eligible study and extracted relevant data. The resulting data were assembled into evidence tables organized by key management questions. The panel derived recommendations that were based on this review of evidence and were formulated according to the ACCP protocol for grading evidence and strength of recommendations.
Key Words: atrial fibrillation • evidence-based medicine • guidelines • methodology • systematic review
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Introduction
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The American College of Chest Physicians (ACCP), through its Health and Science Policy Committee, has had an active and extensive program for developing and implementing clinical practice guidelines, particularly for conditions related to cardiac and pulmonary disease.12 The following report presents the methodological approach that was taken to perform a systematic review of the literature on key questions in the management or prophylaxis of atrial fibrillation or atrial flutter in patients undergoing cardiac surgery.
A panel of recognized experts representing the American College of Chest Physicians, the American College of Cardiology, the American College of Surgeons, the Society of Cardiovascular Anesthesiologists, and the Society of Thoracic Surgeons developed a list of four specific issues to address:
- Controlling the ventricular response rate in atrial fibrillation after cardiac surgery;
- Preventing thromboembolism and the role of anticoagulation therapy in the surgical patient;
- Converting the heart beat to normal sinus rhythm; and
- Prophylaxis to prevent postoperative atrial fibrillation.
Issue 4 was subdivided into the following three areas: perioperative pharmacologic therapy; pacing; and intraoperative management to reduce the incidence of atrial fibrillation.
The Johns Hopkins University Evidence-Based Practice Center conducted a systematic review of the literature on these issues, using several sources to identify studies that were potentially relevant to the study questions. Electronic searches were conducted in PubMed and in CENTRAL, the Cochrane Collaboration database. These searches were augmented by a manual search of 26 cardiology, surgery, and anesthesia journals that were identified by the working group as being of high priority, of the reference lists of relevant review articles, and of the reference lists of selected studies included in the literature review.
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Study Eligibility
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The review was restricted to studies on adult patients undergoing cardiac surgery published between 1964 and December 2001. An abstract review form was developed to determine the eligibility of a study for review. Studies were eligible for review if they were controlled trials that addressed the management or prophylaxis of the postoperative onset of atrial fibrillation or atrial flutter in patients undergoing coronary artery bypass graft or valvular surgery. An additional search was performed to identify randomized trials that addressed the risks and benefits of perioperative anticoagulation therapy in patients undergoing coronary artery bypass grafting. Only human studies in the English language that reported directly on atrial fibrillation, atrial flutter, or both were included in the analysis.
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Assessment of Study Quality
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The form to assess study quality was based on a similar form that had been used in previous systematic reviews by the Johns Hopkins University Evidence-Based Practice Center on the management of atrial fibrillation (see the "Appendix"). The final assessment form contained 23 questions that were related to study quality. These questions were grouped into the following five categories: - Representativeness;
- Bias and confounding;
- Intervention description;
- Outcomes and follow-up; and
- Statistical methods and interpretation.
We assessed representativeness by determining whether the study population as well as the inclusion and exclusion criteria were clearly described. The method of randomization and the degree of masking were used to assess the potential impact of bias and confounding, with the highest quality scores given for those studies in which investigators, treatment supervisors, patients, and outcomes assessors had been blinded. In judging the quality of the intervention description, the completeness of the protocol description and the important differences in ancillary treatment that might influence the outcomes were assessed. We assessed the rigor with which outcomes and follow-up were studied by looking for standardized evaluation techniques and objective outcome assessment procedures. The highest scores were given if there were clear definitions of each outcome and the method of assessment was objective (eg, Holter monitors, head CT scans, or head MRI). Finally, we graded statistical quality and interpretation by reviewing whether appropriate statistical techniques had been used, and whether appropriate adjustments for confounding factors had been made.
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Content Form
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We developed an article content assessment form to extract relevant information from eligible studies in a standardized fashion. Published reports of studies were reviewed by pairs of study investigators with experience in clinical research and a relevant clinical discipline (ie, cardiac surgery, anesthesiology, cardiology, or internal medicine). Two members of the team independently evaluated the quality of each study using the standardized form. The two investigators reviewed any disagreements to achieve consensus. The reviewers were not masked with regard to the author, institution, and journal because such masking has been demonstrated to be ineffective in removing potential reviewer bias.3
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Outcomes Assessment
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For those studies that addressed the first five questions, efficacy was judged in terms of the conversion to sinus rhythm, the incidence of postoperative atrial fibrillation, the incidence of postoperative atrial flutter, the incidence of postoperative atrial fibrillation and/or atrial flutter (if not reported separately), the relapse of atrial fibrillation or atrial flutter, the time to the first episode of atrial fibrillation or atrial flutter following surgery, the mean duration of atrial fibrillation, the rate of all-cause mortality, the rate of cardiovascular disease-specific mortality, the incidence of myocardial infarction, stroke, transient ischemic attack, ventricular or other arrhythmia, normal sinus rhythm at hospital discharge, the length of ICU stay, and the length of hospital stay. Side effects included a decrease in resting heart rate, hemorrhage, and bleeding requiring transfusion. For studies addressing the final question regarding anticoagulation therapy, additional efficacy and side effects assessed included hemorrhagic stroke, nonhemorrhagic stroke, non-CNS arterial embolism, venous thromboembolism, transient ischemic attack, and bleeding requiring transfusion.
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Selection and Organization of Evidence
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In a search of the literature through November 2001, a total of 798 articles, plus 143 articles on anticoagulation therapy, went through the abstract review process. Of the 941 abstracts reviewed, 22 were found by a search of 26 cardiology, surgery, and anesthesia journals. The remaining articles were found through electronic searches conducted in PubMed and CENTRAL, which is the Cochrane Collaboration database, the reference lists of relevant review articles, and the reference lists of a sample of studies included in the literature review.
From the 941 abstracts reviewed, 802 were excluded, with the majority of abstracts being excluded because they reported on the surgical management of nonperioperative atrial fibrillation. The remaining 139 abstracts went through the article review process, and 128 studies were found to address one or more of the following issues: pharmacologic prophylactic therapy (70 studies); pacing (9 studies); intraoperative management (18 studies); treatment to achieve conversion (19 studies); heart rate-controlling agents (11 studies); and the prevention of thromboembolism (12 studies). Of the 128 included studies, 14 studies addressed two of the questions.
From this analysis, a set of tables specific for each of the topic areas was developed. The evidence tables can be viewed on the ACCP Web site at (http://www.chestnet.org). The panel was divided into subgroups for specific topics, and a deliberate attempt was made to mix subspecialties so that each group would consist of experts including a cardiologist, an anesthesiologist, and a surgeon. This was done in an effort to prevent certain biases from dominating the recommendations.
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Grading System for Strength of Evidence and Levels of Recommendations
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From the systematic review of the literature, subgroups graded the strength of evidence and established a grading level for each resulting recommendation. Table 1
summarizes the ACCP grading system that was used to develop the recommendations.
View this table:
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Table 1. Summary of the Relationship of Strength of Recommendations Scale to Quality of Evidence and Net Benefit to Patient
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A system was formulated to present guideline recommendations in a structured "level-of-evidence" fashion that reflects the quality of evidence on which a recommendation is based and places the recommendation in a clinical context. This system for grading evidence and establishing levels of evidence for guidelines recommendations accomplishes the following: - It clearly indicates the support behind each recommendation and, therefore, its strength; and
- It accounts for and explains, either separately or in a combined fashion, both the strength of the recommendation and the quality of the studies that went into the decision on that recommendation (eg, rating of the articles vs rating of the recommendation) or whether expert opinion was the primary deciding factor.
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Quality of the Evidence
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- Good: evidence based on good randomized controlled trials (RCTs) or metaanalyses;
- Fair: evidence based on other controlled trials or RCTs with minor flaws;
- Low: evidence based on nonrandomized, case-control, or other observational studies; and
- Expert opinion: evidence based on the consensus of a carefully selected panel of experts in the topic field. There were no studies that met the criteria for inclusion in the literature review.
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Strength of Recommendation
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The grading of the strength of a recommendation was based on both the quality of the evidence and the net benefit of the diagnostic or therapeutic procedure, 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.
Net Benefit
These levels of net benefit to the patient (adjusted for risk) are based on a clinical assessment of the intervention (eg, a test or procedure), as follows:
- Substantial;
- Intermediate;
- Small/weak;
- None;
- Conflicting; and
- Negative.
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Discussion
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The majority of the selected studies represented RCTs, which represent the highest form of evidence for use in guideline development. Giannakakis and colleagues4 reviewed the use of RCTs in guidelines and demonstrated an increasing number, although some guidelines continue to cite few or no RCTs. We employed multiple strategies to identify relevant articles, including searching PubMed to capture the highest number of articles. To augment the sensitivity of detecting relevant articles, we also searched the Cochrane CENTRAL database for randomized trials, employed manual searches of selected journals for newer articles, and reviewed references from review articles. The data have shown a lack of sensitivity, particularly with respect to randomized clinical trials, using these electronic databases5; therefore, we reviewed a large number of abstracts in order to identify relevant articles. Helmer and colleagues6 demonstrated that the searching of specialized databases, such as Cochrane CENTRAL, was the most effective method of retrieving relevant articles that were not identified in PubMed and that manual searching identified a number of small but potentially unique studies. By using these techniques, we have identified the relevant controlled trials on the subject. We used a predefined protocol for systematic review to minimize bias.7
We employed a quality-assessment form that had been previously used in a systematic review of literature on the management of nonperioperative atrial fibrillation. The overall study quality score and results allow the reader to interpret the actual data in the context of the quality of the evidence. Balk and colleagues8 reviewed metaanalyses to determine the relationship between the quality scores of trials and the treatment effects. Individual quality measures were not reliably associated with the strength of treatment effect across studies and medical areas. Importantly, the quality of the reporting of the trial may not reflect the quality of the trial itself.9 Therefore, the reader must interpret the quality scores in the context of study size and treatment effect.
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Conclusion
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A systematic approach was used to analyze and score the current literature on postoperative atrial fibrillation following cardiac surgery. From this review process, a comprehensive set of clinical practice guidelines was developed in an endeavor to provide guidance to the practicing clinician for the prevention and management of patients with postoperative atrial fibrillation.
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Appendix
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Appendix: Quality Assessment Form
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Footnotes
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Abbreviations: ACCP = American College of Chest Physicians; RCT = randomized controlled trial
This work was supported by a grant from the American College of Chest Physicians.
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References
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- Hirsh, J, Dalen, J, Guyatt, G (2001) The sixth (2000) ACCP guidelines for antithrombotic therapy for prevention and treatment of thrombosis: American College of Chest Physicians. Chest 119(suppl),1S-2S[Free Full Text]
- Heffner, JE, Alberts, WM, Irwin, R, et al Translating guidelines into clinical practice: recommendations to the American College of Chest Physicians. Chest 2000;118(suppl),70S-73S[Free Full Text]
- Berlin, JA Does blinding of readers affect the results of meta-analyses? University of Pennsylvania Meta-analysis Blinding Study Group. Lancet 1997;350,185-186[ISI][Medline]
- Giannakakis, IA, Haidich, AB, Contopoulos-Ioannidis, DG, et al Citation of randomized evidence in support of guidelines of therapeutic and preventive interventions. J Clin Epidemiol 2002;55,545-555[Medline]
- Shaneyfelt, TM, Mayo-Smith, MF, Rothwangl, J Are guidelines following guidelines? The methodological quality of clinical practice guidelines in the peer-reviewed medical literature. JAMA 1999;281,1900-1905[Abstract/Free Full Text]
- Helmer, D, Savoie, I, Green, C, et al Evidence-based practice: extending the search to find material for the systematic review. Bull Med Libr Assoc 2001;89,346-352[ISI][Medline]
- Silagy, CA, Middleton, P, Hopewell, S Publishing protocols of systematic reviews: comparing what was done to what was planned. JAMA 2002;287,2831-2834[Abstract/Free Full Text]
- Balk, EM, Bonis, PA, Moskowitz, H, et al Correlation of quality measures with estimates of treatment effect in meta-analyses of randomized controlled trials. JAMA 2002;287,2973-2982[Abstract/Free Full Text]
- Huwiler-Muntener, K, Juni, P, Junker, C, et al Quality of reporting of randomized trials as a measure of methodologic quality. JAMA 2002;287,2801-2804[Abstract/Free Full Text]
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Abstract
Introduction
