Atrial Fibrillation

Cork CRC AF Algorithm September 2011

Management

Factors

Duration of symptoms
Clinical presentation of the patient
Potential complications of medication and anticoagulation

Duration symptoms

Paroxysmal = episode of AF that terminates spontaneously

Persistent = episode of AF that requires cardioversion

Permanent = AF is resistant to multiple cardioversions

Clinical presentation

May be unstable. If stable and the AF is rate controlled (i.e. ventricular rate less than 80 beats per minute), there is no overt need for hospital admission.

Trigger

AF may be generated by pericarditis, sepsis, pulmonary embolus, or other organic cause. In these cases, it is management of the underlying disorder that leads to cessation of the AF.

Investigations

Full blood count, coagulation, U&E, LFT, TFT, Inflam. markers
Chest X ray
ECG
ECHO to document LA diameter, LV systolic function, any evidence of valvular abnormality, or cardiac pathology

Medication

Rate control strategy

Rate control - 1st line are beta blockers (i.e. metoprolol, bisoprolol) or non dihydropyridone Ca⁺⁺ channel blockers (diltiazem).
Sotalol is reserved for recurrent AF. Sotalol, a nonselective beta blocker with class III antiarrhythmic activity, provides excellent rate control, but due to difficulties in initiation (because it is associated with prolongation of the QT interval, patients started on sotalol need 48 hours monitoring on telemetry) and an increased risk of sudden death in patients with a decreased ejection fraction it is reserved for recurrent AF.
Digoxin is a useful additional therapy in patients poorly controlled on B-blocker/ CCB or in patients with underlying heart failure.
Amiodarone is indicated for rate control in patients who do not achieve adequate rate control on beta-blocker/ CCB/ digoxin or any combination of the above.

Rhythm control strategy

Ibutilide infusion

1g MgSO₄ initially diluted in 50ml saline given over 15 mins
1mg Ibutilide diluted in 50ml saline given over 15 mins
Repeat Ibutilide infusion in 20 mins if still in AF

Flecanide. In patients with lone AF, flecanide or propafenone can be beneficial in maintaining sinus rhythm if treatment is initiated whilst the patient is in sinus.
Ibutilide can be given as an IV infusion in patients who have paroxysmal atrial fibrillation but are symptomatic during their episodes. This should be given after magnesium loading to prevent ventricular dysrhythmia.
Sotalol can be an effective agent in a rhythm control strategy if the QT interval is less than 460 milliseconds, renal function is normal, and there is no LV dysfunction.
Amiodarone is recommended if LV dysfunction and renal impairment.
B blockers are first line agents in patients with coronary artery disease.
Flecanide and propafenone are contraindicated in coronary artery disease
Consider catheter ablation if symptomatic AF with left atrial enlargement on echocardiography.

Cautions restricting medical therapy

Beta blockers - care in asthmatics and LV failure

Diltiazem - raise LFTs and worsen LV function

Digoxin - visual disturbance, heart block (beware overdose)

Amiodarone -NB interaction with Warfarin, rhabdomyolysis, photosensitivity, liver dyscrasias, thyroid dyscrasias

Anticoagulation

Anticoagulation is indicated in all patients with atrial fibrillation, except the 10-15% of cases where there is no structural heart disease and no underlying cause found (‘Lone Afib’)
Warfarin is indicated if one or more risk factors:
- age >75 years, hypertension, diabetes mellitus
- congestive heart failure, previous diagnosis of TIA or CVA
- LV systolic dysfunction (LV ejection fraction 35% or less)
Aspirin 75mg/day if only one major risk factors
In patients who require urgent cardioversion, patients should be anti coagulated with therapeutic dose low molecular weight heparin for 48 hours and commenced on warfarin therapy for six weeks thereafter. Urgent cardioversions should be TOE guided to minimize the risk of embolic stroke.
In situations where a patient requiring warfarin for AF undergoes a PCI, the warfarin should be restarted as soon as practicable post procedure. The drug regimen the patient will be on will therefore include aspirin 75mg, clopidogrel 75mg and warfarin at a therapeutic dose. Clopidogrel should be given for at least 1 month after implantation of a bare metal stent, and at least six months after implantation of a drug eluting stent. Decisions with regard to discontinuing any of this regimen should be done in consultation with the Consultant Cardiologist attending the patient.

Special Considerations

Post Operative AF

AF (no prior Hx) Dx within 5 days of a surgical procedure requiring GA
B blockers to control rate are first line
Amiodarone second line
Ibutalide or DC cardioversion as per non-post op situations

AMI

DC Cardioversion if evidence of ongoing ischaemia or haemodynamic compromise
IV amiodarone infusion indicated to slow a rapid ventricular response to AF and improve LV function in acute MI.
IV beta blockers and the non-dihydropyridine class of calcium channel blockers should be used to effect rate control in acute MI patients who do not show evidence of LV failure, heart block or bronchospasm.
Anticoagulation should be given via unfractionated heparin to a target APTT of 1.5 -2.0 normal, or therapeutic low molecular weight heparin dosage (1mg/ kg body weight twice a day)

Pregnancy

In pregnancy, the rate control medications of choice include digoxin or diltiazem
AF developing during pregnancy, procainamide or quinidine pharmacologically cardiovert
DC Cardioversion if unstable
Anticoagulation (LMWH) in recommended throughout pregnancy for patients with AF.

Wolff Parkinson White

Catheter ablation is treatment of choice
Immediate cardioversion if v rapid AF (risk VF)
Ibutalide is recommended to restore sinus rhythm in patients with AF and WPW who are not haemodynamically compromised.