ATRIAL FIBRILLATION

Preoperative evaluation

• Assess rate control, baseline EF, and presence of valvular heart disease.
• Stop 4 doses of warfarin prior to surgery.  (consider longer e.g. neurosurgery)
• Bridge with low molecular weight heparin if history of TIA/CVA, prior embolic events, or mitral stenosis.  Consider bridge therapy if CHADS2 score is ≥ 3.
• Plan for postoperative rate control and anticoagulation.
• Consider perioperative AV nodal blockers in patients in sinus rhythm who have had previous episodes of perioperative atrial fibrillation.

 

Postoperative management
Pre-existing atrial fibrillation:

• Rate control (i.e. for maintenance control of heart rate).  If NPO, give IV metoprolol (start 5 mg IV q6h, titrate to HR 60-80) or diltiazem drip.  Continue digoxin if already receiving. 
• Transition to usual PO meds when taking POs.
• Resume anticoagulation when surgically acceptable.  Bridge with heparin if indicated.

 

New-onset postop atrial fibrillation:

• Identify precipitating causes (CHF, electrolyte imbalance, infection, infarction, alcohol withdrawal, thyroid abnormalities, anemia, hypovolemia, lung disease, valvular heart disease, pulmonary embolism, volume overload/reabsorbed third spacing).
• Echocardiogram is indicated to assess LVEF and for valvular heart disease.
• Rate control (for atrial fibrillation with rapid ventricular response):

Metoprolol	5 mg IV x 1.  May repeat x 2 if additional rate control needed and BP remains stable.
Diltiazem	Bolus 10-20 mg IV, then start IV drip at 10-20 mg per hour, titrate to HR 80-100.
Digoxin	Acts more slowly.  0.5 mg IV x 1, then 0.25 mg IV Q6H x 2.  Give daily and titrate to effect, typical dose 0.125 mg IV daily.
Amiodarone	150 mg IV bolus, then load with 1 mg/min IV x 6 hrs, then 0.5 mg/min x 18 hrs.  Indicated for refractory atrial fibrillation, heart failure.  Check baseline TSH, PFTs.
Esmolol	50-300 mcg/kg/min IV.  Can bolus 150-300 mcg/kg IV initially.   Watch for hypotension.
PO medications	Multiple options:  Metoprolol, atenolol, diltiazem. PO digoxin and amiodarone if indicated.  Generally start with IV agents if tachycardic and rate control needed urgently.

 

• Anticoagulation:  Postop atrial fibrillation often resolves spontaneously—do not need to anticoagulate unless >48 hrs of atrial fibrillation.  Start anticoagulation after 48 hrs IF bleeding risk is acceptable (must discuss with surgery team) AND the patient meets criteria for anticoagulation: (Ref 1,2)

No risk factors	ASA 81-325 mg daily
1 moderate-risk factor	Aspirin 81-325 mg daily or warfarin (INR 2-3)
Any high-risk factor or >1 moderate risk factor	Warfarin (INR 2-3)
Moderate-risk factors:  Age ≥75, HTN, Heart Failure, LVEF ≤ 35%, DM.
High-risk factors:  Previous stroke, TIA, or embolism; mitral stenosis, prosthetic heart valve (higher INR target if indicated)

Discussion
Anticoagulation and bridging therapy:

• Warfarin does not need to be stopped for certain procedures, e.g. dental extractions, cataract surgery.  Make sure INR is <3.0 and communicate with surgeon to confirm.
• Individualize anticoagulation recommendations for the type of surgery (e.g. neurosurgery, spine surgery, and highly vascular tumors may require a longer period off of anticoagulation), the surgeon’s preference, and the baseline dose of warfarin (patients requiring lower doses tend to have INRs that fall less quickly).
• Most patients do not require bridge therapy (the short-term risk of stroke is low). 
• Low molecular weight heparin therapy can be expensive—check with patient’s insurance for coverage.   Additionally, it is not reversible, a significant postop consideration. 
• Do not assume outpatient procedures are automatically low risk for post-procedure surgical bleeding (e.g. angioembolization).  Discussion with the surgeon or interventionalist should be undertaken.

 Rhythm control:

• Consider rhythm control when:
• There is hemodynamic instability (à DC cardioversion)
• Atrial fibrillation is poorly tolerated: severe valvular heart disease, especially mitral stenosis, ischemia, CHF
• Refractory rapid ventricular response persists despite initial attempts with AV nodal blocker.
• Consider amiodarone in atrial fibrillation that is refractory to rate control, patients with LV dysfunction, or in patients with decompensated CHF.
• Cardiac surgery patients have a high incidence of postoperative atrial fibrillation, and are routinely given prophylactic beta-blockers.  The use of other agents in cardiac surgery is beyond the scope of this handbook.

 

Decision to anticoagulate:

• Consider using the CHADS2 risk score for non-valvular atrial fibrillation (differs slightly from the AHA recommendations above: (Ref 3)

Risk factors: 1 point for CHF, HTN, Age >75, DM; 2 points for history of TIA/CVA.

Score	Annual stroke risk	Anticoagulation		However, if the CHADS2 score is 2 because of history of TIA/CVA, the annual stroke risk is likely greater than 4%. Some elect to use ASA therapy for patients with CHADS2 score of 2.
0	1.9	ASA
1	2.8	ASA or warfarin
2	4.0	Warfarin
3	5.9	Warfarin
4+	>7%	Warfarin

• If atrial fibrillation persists >48 hours but resolves by discharge, then it may still be reasonable not to anticoagulate, depending on the precipitant and the patient’s risk factors.
• Paroxysmal vs. persistent atrial fibrillation:
• For non-surgical patients, we generally do not distinguish paroxysmal from persistent atrial fibrillation with regard to the decision to anticoagulate. 
• Postop patients, however, commonly have brief episodes of atrial fibrillation that resolve once the postoperative stress is over, and they do not necessarily require commitment to lifelong anticoagulation.

 

References

• 1. Fuster V, Ryden LE, Asinger RW, et al.  ACC/AHA/ESC Guidelines for the Management of Patients with Atrial Fibrillation: Executive Summary. J Am Coll Cardiol.  2001;38:1231-1266.
• 2. European Heart Rhythm Association, Heart Rhythm Society, Fuster V, Ryden LE, Cannom DS, et al.  ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation--Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines.  Primary Prevention of Ischemic Stroke: A Guideline from the American Heart Association/American Stroke Association Stroke Council.  J Am Coll Cardiol.  2006;48:854-906.
• 3. Goldstein LB, Adams R, Alberts MJ, et al.  Primary Prevention of Ischemic Stroke: A Guideline From the American Heart Association/American Stroke Association Stroke Council.  Circulation.2006;113;e873-923.

 

 

Updated May 2011