Each recommendation is rated based on the levels of evidence (good, fair, low, and expert opinion) and the net benefit (substantial, intermediate, small/weak, none, conflicting, and negative to determine the grades of the recommendations (A, B, C, D, I, E/A, E/B, E/C, and E/D). Definitions are presented at the end of the "Major Recommendations" field.
Anticoagulation
Summary
While the risk for atrial thrombus formation and stroke must be considered, the potential major complications of postoperative atrial fibrillation (AF) and atrial flutter (AFL), anticoagulation must be considered in light of the complex alterations of coagulation and the risk for enhanced bleeding tendency associated with cardiac surgery and cardiopulmonary bypass. Thus, the relative merits of anticoagulation therapy in patients with AF after cardiac surgery must be weighed against (1) the potential risk for bleeding in a setting of an already enhanced bleeding tendency after major surgery and (2) the typically self-limited history of postoperative AF and AFL. Thus, recommendations for anticoagulation in postoperative patients with AF and AFL include the following (see "Summary of Recommendations" below).
Table: Risk Stratification Schemes for Primary Prevention of Thromboembolism in Patients with Nonvalvular Atrial Fibrillation (adapted from Fuster et al., 2001)
Source |
High Risk |
Intermediate Risk |
Low Risk |
Atrial Fibrillation Investigators (1994) |
Age >65 years; history of hypertension, coronary artery disease, and diabetes |
Age <65 years and no high-risk features |
American College of Chest Physicians (1998) |
Age >75 years; history of hypertension, left ventricular dysfunction; >1 intermediate risk factor |
Age 65-75 years; diabetes, coronary artery disease, or thyrotoxicosis |
Age <65 years and no risk factors |
Stroke Prevention in Atrial Fibrillation (1995) |
Women aged >75 years; systolic blood pressure >160 mm Hg; left ventricular dysfunction |
History of hypertension and no high-risk features |
No high-risk features and no history of hypertension |
Summary of Recommendations
- In optimally selected patients with chronic AF and in those patients in whom it is thought to be likely that AF will continue postoperatively, the expert panel recommends anticoagulation therapy (strength of recommendation, A; evidence grade, good; net benefit, substantial).
- In the high-risk patient with postoperative AF, such as those with a history of stroke or transient ischemic attack, the routine use of heparin should be considered (strength of recommendation, C; evidence grade, low; net benefit, intermediate).
- The expert panel recommends continuing anticoagulation therapy for 30 days after the return of normal sinus rhythm because of the prior demonstration of persistent impairment of atrial contraction and a presumably enhanced risk for thrombosis following the conversion of postoperative AF (strength of recommendation, C; evidence grade, low; net benefit, intermediate).
Intraoperative Interventions
Recommendations
AF remains a significant complication following cardiac surgery. This arrhythmia is associated with an increased hospital length of stay, increased costs, and an increased risk for thromboembolic complications. On the basis of the findings of this and the other reports in this series, the expert panel suggests that a multifactorial approach, involving appropriate prophylaxis and treatment for this arrhythmia, will best serve cardiac surgery patients. Below are the recommendations for the management of intraoperative interventions. A summary of these clinical recommendations and grades of evidence is presented in Table 2 of the chapter titled "Intraoperative Interventions" in the original guideline document.
- The expert panel recommends the use of mild, rather than moderate, hypothermia to reduce the frequency of postoperative AF (strength of recommendation, A; evidence grade, fair; net benefit, substantial).
- Posterior pericardiotomy may be a useful adjunct to help reduce the incidence of postoperative atrial arrhythmias; however, this recommendation is based on a single, small-scale randomized, controlled trial. Posterior pericardiotomy is not currently standard of care and is not widely used as an adjunct to reduce postoperative AF (strength of recommendation, B; evidence grade, fair; net benefit, intermediate).
- Off-pump coronary bypass graft (OPCAB) cannot be recommended to decrease postoperative AF because of conflicting results reported from randomized, controlled trials or large-scale concurrent cohort studies (strength of recommendation, I; evidence grade, fair; net benefit, conflicting).
- No specific recommendations can be made regarding which type of cardioplegia (or intermittent aortic cross-clamping) best reduces the incidence of postoperative AF (strength of recommendation, I; evidence grade, good; net benefit, none).
- No recommendation can be made regarding the use of thoracic epidural anesthesia (TEA) as an adjunct to conventional general anesthesia to prevent postoperative AF after cardiac surgery (strength of recommendation, I; evidence grade, fair; net benefit, conflicting).
- The expert panel cannot recommend glucose-insulin-potassium (GIK) solution infusion to prevent postoperative AF because of conflicting results from the identified randomized, controlled trials (strength of recommendation, I; evidence grade, fair; net benefit, conflicting).
- The expert panel recommends the use of heparin-coated circuits to reduce the rate of postoperative AF (strength of recommendation, B; evidence grade, fair; net benefit, intermediate).
The Role of Cardiac Pacing
Summary of Recommendations
Atrial pacing appears to reduce the incidence of AF after cardiac surgery in some studies. Biatrial pacing (BAP) appears to be the most efficacious. Right atrial (RA) pacing alone may reduce the incidence of AF, while left atrial (LA) pacing alone does not appear to reduce the incidence, at least based on the limited data currently available. The recommendations are also summarized in Table 1 of the chapter titled "The Role of Cardiac Pacing" in the original guideline document.
- The expert panel does not recommend right atrial pacing alone to reduce postoperative AF after cardiac surgery (strength of recommendation, I; evidence grade, fair; net benefit, small/weak).
- The expert panel does not recommend isolated left atrial pacing to prevent postoperative AF following cardiac surgery (strength of recommendation, I; evidence grade, fair; net benefit, none).
- The expert panel recommends biatrial pacing to help prevent postoperative AF (strength of recommendation, B; evidence grade, good; net benefit, small/weak).
Pharmacologic Prophylaxis
A number of antiarrhythmic drugs and classes of drugs have been found to demonstrate varying degrees of efficacy in preventing new-onset AF after cardiac surgery.
- In patients in whom prophylaxis against post-cardiac surgery AF is indicated, including those patients receiving long-term therapy with beta-blockers prior to surgery for whom therapy should be reinstated, the expert panel recommends the use of Vaughan-Williams class II beta-blockers (strength of recommendation, A; evidence grade, fair; net benefit, substantial).
- Sotalol (Vaughan-Williams class III agent) therapy may be considered for postoperative AF prophylaxis but is associated with increased toxicity (strength of recommendation, B; evidence grade, good; net benefit, intermediate).
- In individual patients for whom therapy with class II beta-blockers are contraindicated, therapy with amiodarone should be considered (strength of recommendation, B; evidence grade, good; net benefit, intermediate).
- To prevent AF/AFL in patients following cardiac surgery, the expert panel recommends against the use of calcium channel antagonists (i.e., verapamil and diltiazem) (strength of recommendation, D; evidence grade, low; net benefit, none).
- For the prevention of AF/AFL in patients following cardiac surgery, the expert panel recommends against routine treatment with magnesium (strength of recommendation, D; evidence grade, low; net benefit, none).
- For reducing the incidence of post-surgical AF, the expert panel does not recommend digitalis for use as monotherapy (strength of recommendation, I; evidence grade, low; net benefit, none).
Table 1 in the chapter titled, "Pharmacologic Prophylaxis" in the original guideline document provides the results and evidence grades for other prophylactic therapies evaluated in a few small studies. These therapies include dexamethasone, insulin-induced cardioplegia, triiodothyronine, procainamide, alinidine, quinidine, and glucose-insulin-potassium. The merits of these agents in preventing postoperative AF are unclear because of the limited evidence. Therefore, these agents, although cited in the text and in Table 1, were not included in the above summary of recommendations.
Pharmacologic Control of Rhythm
Summary of Recommendations
In patients who do not require emergent cardioversion, pharmacologic agents for control of postoperative AF and AFL are selected for use due to their efficacy in converting AF to normal sinus rhythm in the immediate postoperative period and in maintaining normal sinus rhythm postoperatively (see Table 4 in the chapter titled, "Pharmacologic Control of Rhythm" in the original guideline document). Antiarrhythmic drugs that are administered to maintain normal sinus rhythm are customarily continued for 4 to 6 weeks postoperatively. Because of a dearth of high-quality evidence regarding pharmacologic therapy for the maintenance of postoperative normal sinus rhythm after conversion of postoperative AF or AFL, recommendations for the pharmacologic maintenance of normal sinus rhythm postoperatively were extrapolated from recommendations for non-surgical patients with AF. In all instances, the choice of a drug or drugs to convert postoperative AF or AFL and subsequently to maintain normal sinus rhythm must be determined for each patient based on individual clinical characteristics. It is advisable to restore and maintain sinus rhythm for patients with postoperative AF or AFL that is complicated by significant symptoms or hemodynamic instability. Early cardioversion within 48 hours should be considered in patients with a contraindication to anticoagulation therapy. When these clinical conditions are absent, a strategy of rate control may be equivalent to one of rhythm control.
Torsades de pointes and bradycardia are major complications of antiarrhythmic therapy. Patients should be monitored closely by continuous telemetry and should have access to a defibrillator when therapy with antiarrhythmic drugs is started during AF. Epicardial or transvenous pacing may be helpful to prevent torsades de pointes, pauses, or bradycardia.
Table 1 of the chapter titled "Pharmacologic Control of Rhythm" in the original guideline document summarizes the various agents used for rhythm control in AF with conversion and relapse rates. Tables 2 and 3 of that same chapter in the original guideline document list the doses and toxicities for drugs used for the conversion to and maintenance of sinus rhythm, respectively. Finally, Table 4 provides a summary of the evidence and strength of recommendations for each intervention.
- In patients with depressed left ventricular function in whom maintaining sinus rhythm is important, the expert panel recommends therapy with amiodarone (strength of recommendation, E/C; evidence grade, low; net benefit, intermediate).
- In patients without heart failure, the expert panel recommends therapy with amiodarone, sotalol, or ibutilide, or, alternatively, class 1A agents for the conversion of AF following cardiac surgery (strength of recommendation, C [E/C for amiodarone]; evidence grade, low; net benefit, intermediate).
- In patients with AF after cardiac surgery, the expert panel recommends 4 to 6 weeks of antiarrhythmic therapy (strength of recommendation, E/C; evidence grade, low; net benefit, small/weak).
- In patients with AF following cardiac surgery, the expert panel cannot at this time recommend using flecainide, digoxin, or calcium channel blockers for the purpose of conversion to sinus rhythm (strength of recommendation, I; evidence grade, low; net benefit, none).
- In patients with AF following cardiac surgery, the expert panel recommends against therapy with dofetilide and class 1C agents for conversion to sinus rhythm (strength of recommendation, D; evidence grade, low; net benefit, negative).
Pharmacologic Control of Ventricular Rate
The pharmacologic management of the ventricular rate in postoperative AF or AFL patients with a rapid ventricular response is a problem that must frequently be addressed after cardiac surgery. A summary of the evidence grade, net benefit, and overall strength of the recommendations for pharmacologic agents is presented in the Table 2 in the chapter titled, "Pharmacologic Control of Ventricular Rate" in the original guideline document. The pharmacologic management of ventricular rate must be considered in the total context of the management of postoperative AF and AFL.
- In patients with postoperative AF and AFL who do not need urgent cardioversion and have no contraindication to anticoagulation therapy, therapy with beta-blockers is recommended as the first-line pharmacologic choice for ventricular rate control (Andrews et al., 1991; Balser et al., 1998; Maisel, Rawn, & Stevenson, 2001). This recommendation is based on a limited amount of evidence, but the recommendation is made in consideration of the hyperadrenergic state that typically exists after surgery and the effect of beta-blockers on adrenergic tone (strength of recommendation, B; evidence grade, low quality; net benefit, intermediate).
- For patients with postoperative AF and AFL, the expert panel recommends the calcium channel blockers diltiazem and verapamil as second-line choices for ventricular rate control (strength of recommendation, B; evidence grade, low quality; net benefit, intermediate).
- In the setting of postoperative AF or AFL, the expert panel does not consider amiodarone to be a first-line or first-alternative choice for ventricular rate control. While amiodarone may be used as an alternative to beta-blockers or calcium channel blockers, limited evidence suggests that excessive bradycardia or respiratory dysfunction (Ashrafian & Davey, 2001) may be side effects in some patients (strength of recommendation, I; evidence grade, low; net benefit, small/weak).
- In the setting of postoperative AF or AFL, digoxin is not considered to be a first-line or first-alternative choice for ventricular rate control. Although digoxin is widely used to treat postoperative AF and AFL, it has no effect on adrenergic tone and therefore may not be as efficacious for rate control in patients with AF or AFL. Limited evidence indicates that digoxin may not be more effective than diltiazem or amiodarone in controlling ventricular rate in patients with postoperative AF (strength of recommendation, I; evidence grade, low; net benefit, none).
- For the control of ventricular rate in patients with postoperative AF or AFL, the expert panel recommends against the use of any drugs that may be, or have been shown to be, proarrhythmic. While propafenone may be efficacious in controlling ventricular rate in patients with postoperative AF or AFL, it has a potential to cause bradycardia and should not be given to patients with coronary artery disease (Roy et al., 2000). Dofetilide is not considered to be efficacious and may be proarrhythmic (strength of recommendation, D; evidence grade, low quality; net benefit, negative).
Definitions:
Quality of Evidence
Good: Evidence based on good randomized controlled trials (RCTs) or metaanalyses
Fair: Evidence based on other controlled trials or randomized controlled trials with minor flaws
Low: Evidence based on nonrandomized, case-control, or other observational studies
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.
Strength of Recommendation
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
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 (e.g., a test of procedure), as follows:
- Substantial
- Intermediate
- Small/weak
- None
- Conflicting
- Negative
Table: Summary of the Relationship of Strength of Recommendations Scale to Quality of Evidence and Net Benefit to Patient
|
Net Benefit |
Quality of Evidence |
Substantial |
Intermediate |
Small/Weak |
None |
Conflicting |
Negative |
Good |
A |
A |
B |
D |
I |
D |
Fair |
A |
B |
C |
D |
I |
D |
Low |
B |
C |
C |
I |
I |
D |
Expert Opinion |
E/A |
E/B |
E/C |
E/I |
E/I |
E/D |