Atrial fibrillation resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Vidit Bhargava, M.B.B.S [2]; Hilda Mahmoudi M.D., M.P.H.^[3]; Priyamvada Singh, M.D. [4]; Rim Halaby, M.D. [5]

Synonyms and keywords: AF, Afib

Definitions

Atrial fibrillation is a supraventricular tachyarrhythmia characterized by uncoordinated atrial activation leading to an irregularly irregular rhythm and absent P waves on ECG.

▸ Paroxysmal	AF lasting < 7 days (mostly < 24 hours), usually self terminating
▸ Persistent	AF lasting > 7 days, usually does not terminate on its own
▸ Permanent	AF lasting for a longer period, an attempted cardioversion has failed or promises no improvement
▸ Lone AF	AF in patients > 60 years without any pre-existing cardiopulomunary diseases

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated. Atrial fibrillation can be a life-threatening condition and must be treated as such irrespective of the causes.

Common Causes

• Alcohol abuse
• Congestive heart failure
• Coronary artery disease
• Dehydration
• Electrolyte disturbance
• Hypertensive heart disease
• Hyperthyroidism
• Hypothermia
• Hypoxia
• Myocardial infarction
• Myocarditis
• Pericarditis
• Pulmonary embolism
• Rheumatic heart disease
• Uremic pericarditis

Management

Shown below is an algorithm summarizing the initial approach to atrial fibrillation.

		Characterize the symptoms: ❑ Asymptomatic ❑ Palpitations ❑ Dyspnea ❑ Fatigue ❑ Chest discomfort ❑ Lightheadedness ❑ Syncope Characterize the timing of the symptoms: ❑ Onset ❑ First episode ❑ Recurrent ❑ Duration ❑ Frequency ❑ Termination of the episode ❑ Spontaneous ❑ Medication use ❑ Not terminated
		Identify possible triggers: ❑ Infection ❑ Caffeine ❑ Alcohol ❑ Nicotine ❑ Recreational drugs ❑ Hypovolemia ❑ Hyperthyroidism ❑ Hypoxia ❑ Acidosis ❑ Hypokalemia ❑ Hyperkalemia ❑ Hypoglycemia ❑ Hypothermia ❑ Toxins ❑ Cardiac tamponade ❑ Pulmonary embolism ❑ Coronary thrombosis ❑ Trauma
		❑ Examine the patient ❑ Order an ECG ♦ Atrial fibrillation rhythm ❑ Irregularly irregular rhythm ❑ Absent P waves ❑ Atrial rate 400-700 beats/minute ❑ Ventricular rate 75-180 beats/minute ♦ Other signs on ECG ❑ Left ventricular hypertrophy ❑ Preexcitation ❑ Bundle branch block ❑ Previous myocardial infarction ❑ Other types of arrhythmias
		❑ Order a transthoracic echocardiogram ❑ Order blood tests (if AF has not been investigated before) ❑ Thyroid function ❑ Renal function ❑ Hepatic function

Newly Discovered Atrial Fibrillation

Shown below is an algorithm depicting the pharmacological management of patients with newly discovered atrial fibrillation based on the 2011 ACCF/AHA/HRS updates for the management of atrial fibrillation.

Newly discovered AF

Paroxysmal AF

Persistent AF

Accept progression to permanent AF

Restore sinus rhythm

❑ Do not administer therapy unless the patient has any of the following symptoms requiring DC cardioversion ❑ Hypotension ❑ Heart failure ❑ Angina pectoris ❑ Administer long term anticoagulation therapy based on the risk of stroke ❑ Measure INR weekly initially, then monthly when stable (class I, level of evidence A) ❑ Reassess need for anticoagulation at periodic intervals (class IIa, level of evidence C)

❑ Administer long term anticoagulation therapy based on the risk of stroke ❑ Control the ventricular rate

❑ Administer anticoagulation therapy based on the risk of stroke ❑ Administer rate control therapy THEN ❑ Attempt for cardioversion THEN ❑ Administer short term antiarrhythmic drugs

Note: For the treatment of newly persistent AF, choose the therapy depending on the severity of symptoms and the risk of administration of anti-arrhythmic.

Recurrent Paroxysmal Atrial Fibrillation

Shown below is an algorithm depicting the pharmacological management of patients with recurrent paroxysmal atrial fibrillation based on the 2011 ACCF/AHA/HRS updates for the management of atrial fibrillation.

Recurrent paroxysmal AF

Minimal or no symptoms

Disabling symptoms in AF

❑ Administer rate control ❑ Administer anticoagulation therapy based on the risk of stroke ❑ Avoid antiarrhythmic

❑ Administer rate control ❑ Administer anticoagulation therapy based on the risk of stroke ❑ Administer antiarrhythmic ❑ Sustained dose ❑ Pill in the pocket

❑ Consider AF ablation if antiarrhythmic treatment fails

Recurrent Persistent Atrial Fibrillation

Shown below is an algorithm depicting the pharmacological management of patients with recurrent persistent atrial fibrillation based on the 2011 ACCF/AHA/HRS updates for the management of atrial fibrillation.

Recurrent persistent AF

Minimal or no symptoms

Disabling symptoms in AF

❑ Administer rate control ❑ Administer anticoagulation therapy based on the risk of stroke

❑ Administer rate control ❑ Administer anticoagulation therapy based on the risk of stroke ❑ Administer antiarrhythmic THEN ❑ Attempt for cardioversion

❑ Continue anticoagulation therapy ❑ Continue antiarrhythmic

In case of recurrence of AF, proceed with: ❑ Left atrial ablation ❑ Maze procedure ❑ AV nodal ablation and pacing

Permanent Atrial Fibrillation

Shown below is an algorithm depicting the pharmacological management of patients with permanent atrial fibrillation based on the 20011 ACCF/AHA/HRS updates for the management of atrial fibrillation.

Permanent AF
❑ Administer anticoagulation therapy based on the risk of stroke ❑ Administer rate control

Maintenance of Sinus Rhythm

Shown below is an algorithm depicting the antiarrhythmic drug therapy for maintaining sinus rhythm in patients with recurrent paroxysmal or persistent atrial fibrillation based on the 20011 ACCF/AHA/HRS updates for the management of atrial fibrillation. Drugs are listed alphabetically and not in order of suggested use.

Maintenance of sinus rhythm

No or minimal heart disease

Hypertension

Coronary artery disease

Heart failure

First line therapy: ❑ Dronedarone ❑ Flecainide ❑ Propafenone ❑ Sotalol

Substantial LVH

❑ Dronedarone ❑ Dofetilide ❑ Sotalol

❑ Amiodarone ❑ Dofetilide

Second line therapy: ❑ Amiodarone ❑ Dofetilide

❑ Catheter ablation

No

Yes

❑ Amiodarone

❑ Catheter ablation

❑ Catheter ablation

❑ Dronedarone ❑ Flecainide ❑ Propafenone ❑ Sotalol

❑ Amiodarone

❑ Catheter ablation

❑ Amiodarone ❑ Dofetilide

❑ Catheter ablation

Maintenance of Sinus Rhythm ▸ Amiodarone (100 to 400 mg) OR ▸ Disopyramide (400 to 750 mg) OR ▸ Dofetilide (500 to 1000 mcg) OR ▸ Flecainide (200 to 300 mg) OR ▸ Procainamide (1000 to 4000 mcg) OR ▸ Propafenone (450 to 900 mg) OR ▸ Quinidine (600 to 1500 mg) OR ▸ Sotalol (160 to 320 mg)

Note:

• In vagally mediated AF, disopyramide and flecainide are recommended.
• In adrenergically mediated AF, beta blocker and sotalol are recommended.

Heart Rate Control

Shown below is a table summarizing the list of recommended agents for control of heart rate and their dosages.

Heart Rate Control in Acute Setting Drug Loading dose Maintenance dose Heart rate control in patients without accessory pathway ▸ Esmolol (class I, level of evidence C) ▸ 500 mcg/kg IV over 1 min ▸ 60 to 200 mcg/kg/min IV ▸ Propanolol (class I, level of evidence C) ▸ 0.15 mg/kg IV ▸ NA ▸ Metoprolol (class I, level of evidence C) ▸ 2.5 to 5 mg IV bolus over 2 min; up to 3 doses ▸ NA ▸ Diltiazem (class I, level of evidence B) ▸ 0.25 mg/kg IV over 2 min ▸ 5 to 15 mg/h IV ▸ Verapamil (class I, level of evidence B) ▸ 0.075 to 0.15 mg/kg IV over 2 min ▸ NA Heart rate control in patients with accessory pathway ▸ Amiodarone (class IIa, level of evidence C) ▸ 150 mg over 10 min ▸ 0.5 to 1 mg/min IV Heart Rate Control in patients with heart failure and without accessory pathway ▸ Digoxin (class I, level of evidence B) ▸ 0.25 mg IV each 2 h, up to 1.5 mg ▸ 0.125 to 0.375 mg daily IV or orally ▸ Amiodarone (class IIa, level of evidence C) ▸ 150 mg over 10 min ▸ 0.5 to 1 mg/min IV Heart Rate Control in Non Acute Setting and Long Term Maintenance Heart rate control ▸ Metoprolol (class I, level of evidence C) ▸ 25 to 100 mg twice a day, orally ▸ 25 to 100 mg twice a day, orally ▸ Propanolol (class I, level of evidence C) ▸ 80 to 240 mg daily in divided doses, orally ▸ 80 to 240 mg daily in divided doses, orally ▸ Verapamil (class I, level of evidence B) ▸ 120 to 360 mg daily in divided doses, orally ▸ 120 to 360 mg daily in divided doses, orally ▸ Diltiazem (class I, level of evidence B) ▸ 120 to 360 mg daily in divided doses, orally ▸ 120 to 360 mg daily in divided doses, orally Heart Rate Control in patients with heart failure and without accessory pathway ▸ Digoxin (class I, level of evidence B) ▸ 0.5 mg by mouth daily ▸ 0.125 to 0.375 mg daily, orally ▸ Amiodarone (class IIb, level of evidence C) ▸ 800 mg daily for 1 week, orally 600 mg daily for 1 week, orally 400 mg daily for 4 to 6 week, orally ▸ 200 mg daily, orally

Anticoagulation Therapy

Shown below are tables depicting the assessment of risk of stroke and the appropriate anticoagulation therapy among patients with AF.

Anticoagulation Therapy No risk factors ▸ Aspirin 81-325 mg daily 1 Moderate risk factor ▸ Aspirin 81-325 mg daily OR ▸ Warfarin (INR 2.0 to 3.0, target 2.5) Any high risk factor or more than 1 moderate risk factor ▸ Warfarin (INR 2.0 to 3.0, target 2.5)

Low Risk Factors	Moderate Risk Factors	High Risk Factors
▸ Female gender ▸ Age 65-74 years ▸ Coronary artery disease ▸ Thyrotoxicosis	▸ Age ≥ 75 years ▸ Hypertension ▸ Heart failure ▸ LV ejection fraction ≤ 35% ▸ Diabetes mellitus	▸ Previous stroke, TIA or embolism ▸ Mitral stenosis ▸ Prosthetic heart valve

Pharmacological Cardioversion

Shown below is a table summarizing the pharmacological cardioversion for atrial fibrillation of a duration less or more than 7 days.

Pharmacological Cardioversion for Atrial Fibrillation of a Duration Up to 7 Days Drug Dosage ▸ Dofetilide (class I, level of evidence A) ▸ Oral dose depends on creatinine clearance (ml/min): ▸ > 60: 500 mg, BID ▸ 40 to 60: 250 mg, BID ▸ 20 to 40: 125 mg, BID ▸ < 20: contraindicated ▸ Flecainide (class I, level of evidence A) ▸ Oral: 200 to 300 mg ▸ Intravenous: 1.5 to 3.0 mg/kg, over 10 to 20 min ▸ Ibutilide (class I, level of evidence A) ▸ Intravenous: 1 mg over 10 min, repeat 1 mg if necessary ▸ Propafenone (class I, level of evidence A) ▸ Oral: 600 mg ▸ Intravenous: 1.5 to 2.0 mg/kg, over 10 to 20 min ▸ Amiodarone (class IIa, level of evidence A) ▸ Oral: Inpatient ▸ 1.2 to 1.8 g per day in divided dose until a maximum of 10 g ▸ Followed by a maintenance dose of 200 to 400 mg per day or 30 mg/kg Outpatient ▸ 600 to 800 mg per day divided dose until a maximum of 10 g ▸ Followed by a maintenance dose of 200 to 400 mg per day ▸ Intravenous: 5 to 7 mg/kg, over 30 to 60 min Followed by 1.2 to 1.8 g per day continuous IV OR 5 to 7 mg/kg, in divided oral doses until a maximum of 10 g Followe by a maintenance dose of 200 to 400 mg per day Pharmacological Cardioversion for Atrial Fibrillation of a Duration More Than 7 Days Drug Dosage ▸ Dofetilide (class I, level of evidence A) ▸ Oral dose depends on creatinine clearance (ml/min): ▸ > 60: 500 mg, BID ▸ 40 to 60: 250 mg, BID ▸ 20 to 40: 125 mg, BID ▸ < 20: contraindicated ▸ Ibutilide (class IIa, level of evidence A) ▸ Intravenous: 1 mg over 10 min; repeat 1 mg when necessary ▸ Amiodarone (class IIa, level of evidence A) ▸ Oral: Inpatient ▸ 1.2 to 1.8 g per day in divided dose until a maximum of 10 g ▸ Followed by a maintenance dose of 200 to 400 mg per day or 30 mg/kg Outpatient ▸ 600 to 800 mg per day divided dose until a maximum of 10 g ▸ Followed by a maintenance dose of 200 to 400 mg per day ▸ Intravenous: 5 to 7 mg/kg, over 30 to 60 min Followed by 1.2 to 1.8 g per day continuous IV OR 5 to 7 mg/kg, in divided oral doses until a maximum of 10 g Followe by a maintenance dose of 200 to 400 mg per day

Do's

Rate Control

• Begin therapy with either a beta blocker, diltiazem, or verapamil (class I, level of evidence B). Use a combination of digoxin and either a beta blocker, diltiazem, or verapamil if AF is not controlled by monotherapy (class IIa, level of evidence B).

• Administer ablation of the arterioventricular (AV) node or accessory pathway if pharmacological therapy is insufficient (class IIa, level of evidence B).

• If rate is not controlled by the above measures administer oral or IV amiodarone either alone or in combination with other agents (class IIb, level of evidence C).

Antithrombotic Therapy

• Dabigatran may be administered as an alternative to warfarin in patients who do not have any of the following (class I, level of evidence B):

• Prosthetic heart valve
• Hemodynamically significant valve disease
• Severe renal failure (creatinine clearance < 15 mL/min)
• Advanced liver disease (impaired baseline clotting function)

• Administer anticoagulants 3 weeks prior to and 4 weeks after cardioversion for patients with unknown duration of AF or AF for > 48 hours (class I, level of evidence B). Patients who require immediate cardioversion should be administered IV heparin followed by 4 weeks of oral anticoagulant therapy.

• If a patient is on anticoagulants for AF develops stroke or systemic embolism, target INR may be raised to 3.0 - 3.5 (class IIb, level of evidence C).

• Anticoagulation therapy can be interrupted for up to 1 week if patients require a procedure that carries an elevated risk of bleeding (class IIa, level of evidence C). If anticoagulation therapy has to be interrupted for more than 1 week, unfractionated or low molecular weight heparin may be given intravenously (class IIb, level of evidence C).

Cardioversion

• Use a rate control agent such as beta blocker, diltiazem or verapamil before initiating antiarrhythmic medication to prevent rapid AV conduction (class IIa, level of evidence C).
• Perform cardioversion immediately in patients with AF of less than 48 hours duration without a need for anticoagulation (class I, level of evidence C).
• Attempt electrical cardioversion in patient who fail pharmacological cradioversion as well as in hemodynamically unstable patients.
• Transesophageal echocardiography may be used to search for thrombus prior to cardioversion. If no thrombus is detected, the patient may be treated with 4 weeks of anticoagulants after the procedure (class IIa, level of evidence B). If a thrombus is detected, anticoagulant therapy 3 weeks prior and 4 weeks after cardioversion is required (class IIa, level of evidence C).

Dont's

• Perform cardioversion immediately without giving anticoagulants in a patient with hemodynamic instability. Administer IV unfractionated heparin or SC injection of a low-molecular-weight heparin.
• Do not administer digoxin as a single agent for rate control in patients with paroxysmal AF (class III, level of evidence B).
• Do not attempt catheter ablation unless a trial of medication to control ventricular rate has been made (class III, level of evidence C).
• Do not give IV nondihydropyridine calcium channel antagonist in a patient with decompensated heart failure and AF.
• Do not use digoxin and sotalol for pharmacological cardioversion of AF (class III, level of evidence A).
• Do not initiate treatment with quinidine, procainamide, disopyramide, or dofetilide in an out of hospital setting (class III, level of evidence B).
• Do not perform repeated electric cardioversion in patients with short periods of normal sinus rhythm in between (class III, level of evidence C).
• Do not perform electric cardioversion in those with digitalis toxicity and/or hypokalemia (class III, level of evidence C).
• Do not administer calcium channel blocker, beta blocker, and digoxin in atrial fibrillation patients with Wolf Parkinson White.

References

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