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
• Hyperhtyroidism
• Hypothermia
• Hypoxia
• Myocardial infarction
• Myocarditis
• Pericarditis
• Pulmonary embolism
• Rheumatic heart disease
• Uremic pericarditis

Management

Shown below is an algorithm summarizing the initial approach to evaluation of AF.

		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 EKG ♦ 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 ❑ 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 20011 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 ant 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: Algorithm based on the 20011 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 based on the risk of stroke ❑ Avoid antiarrhythmic

❑ Administer rate control ❑ Administer anticoagulation 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: Algorithm based on the 20011 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 based on the risk of stroke

❑ Administer rate control ❑ Administer anticoagulation 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:Algorithm based on the 20011 ACCF/AHA/HRS updates for the management of atrial fibrillation.

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

Antiarrhythmic Drug Therapy in Atrial Fibrillation

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.

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

Note:

• Drugs are listed alphabetically and not in order of suggested use.
• In vagally mediated AF, disopyramide and flecainide are recommended.
• In adrenergically mediated AF, beta blocker and sotalol are recommended.

Shown below is a table summarizes the list of most commonly used drugs and their dosages for maintenance of sinus rhythm:

Drug & Dosage

▸ 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)

Pharmacological Cardioversion

Cardioversion up to 7 Days

Drug	Dosage
Agents with proven efficacy
▸ Dofetilide (Class of recommendation I Level of evidence A)	▸ Creatinine clearance(ml/min): > 60 - 500 mg 40 to 60 - 250 mg 20 to 40 - 125 mg < 20 - contraindicated
▸ Flecainide (Class of recommendation 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 of recommendation I Level of evidence A)	▸ 1 mg over 10 min; repeat 1 mg when necessary
▸ Propafenone (Class of recommendation I Level of evidence A)	▸ Oral: 600 mg Intravenous: 1.5 to 2.0 mg/kg over 10 to 20 min
▸ Amiodarone (Class of recommendation IIa Level of evidence A)	▸ Oral: Inpatient: 1.2 to 1.8 g per day in divided dose until 10 g total then 200 to 400 mg per day maintenance or 30 mg/kg as single dose Outpatient: 600 to 800 mg per day divided dose until 10 g total then 200 to 400 mg per day maintenance. Intravenous: 5 to 7 mg/kg over 30 to 60 min then 1.2 to 1.8 g per day continuous IV or in divided oral doses until 10 g total then 200 to 400 mg per day maintenance.

Cardioversion after 7 Days

Drug	Dosage
Agents with proven efficacy
▸ Dofetilide (Class of recommendation I Level of evidence A)	▸ Creatinine clearance(ml/min): > 60 - 500 mg 40 to 60 - 250 mg 20 to 40 - 125 mg < 20 - contraindicated
▸ Ibutilide (Class of recommendation I Level of evidence A)	▸ 1 mg over 10 min; repeat 1 mg when necessary
▸ Amiodarone (Class of recommendation IIa Level of evidence A)	▸ Oral: Inpatient: 1.2 to 1.8 g per day in divided dose until 10 g total then 200 to 400 mg per day maintenance or 30 mg/kg as single dose Outpatient: 600 to 800 mg per day divided dose until 10 g total then 200 to 400 mg per day maintenance. Intravenous: 5 to 7 mg/kg over 30 to 60 min then 1.2 to 1.8 g per day continuous IV or in divided oral doses until 10 g total then 200 to 400 mg per day maintenance.

Drugs which enhance the efficacy of electric cardioversion when given prior to the procedure: (Level of recommendation: IIa B)

• Amiodarone
• Flecainide
• Ibutilide
• Propafenone
• Sotalol

Risk Factors for Stroke and Recommended Antithrombotic Therapy

Shown below is a table used to categorize the risk of stroke in a patient with AF:

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

Shown below is a table illustrating anticoagulant therapy based on risk factors:

Risk Category & Recommended Therapy

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

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 wk, orally 600 mg daily for 1 wk, orally 400 mg daily for 4 to 6 wk, orally ▸ 200 mg daily, orally

Do's

Rate control during AF:

• Begin therapy with either a beta blocker, diltiazem, or verapamil. (Class of recommendation I Level of evidence B) Use a combination of digoxin and either a beta blocker, diltiazem, or verapamil if AF not controlled by monotherapy. (Class of recommendation IIa Level of evidence B)
• Use ablation of the arterioventricular (AV) node or accessory pathway, if pharmacological therapy is insufficient. (Class of recommendation IIa Level of evidence B)
• If rate is not controlled by above measures use oral or IV amiodarone, either alone or in combination with other agents. (Class of recommendation IIb Level of evidence C)

Antithrombotic therapy:

• Dabigatran may be used as an alternative to warfarin in those wdo don't have: (Class of recommendation I Level of evidence B)

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

• Give anticoagulants 3 weeks prior to & 4 weeks after cardioversion for patients with unknown duration of AF or AF > 48 hours. (Class of recommendation I Level of evidence B) Those requiring immediate cardioversion should be given IV heparin, followed by 4 weeks of oral anticoagulant therapy.
• If patient on anticoagulants with AF sustains stroke or systemic embolism, target INR may be raised to 3.0 - 3.5 (Class of recommendation IIb Level of evidence C) .
• Anticoagulation therapy can be interrupted for upto 1 week, if patients needs a procedure that carries a risk of bleeding (Class of recommendation IIa Level of evidence C) . For periods > 1 week unfractionated or low molecular weight heparin may be given IV (Class of recommendation 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 of recommendation IIa Level of evidence C)
• Perform cardioversion immediately in AF < 48 hours without a need for anticoagulation. (Class of recommendation I Level of evidence C)
• Transesophageal echocardiography may be used to search for thrombus prior to cardioversion, if none are found patient may be treated with 4 weeks of anticoagulants after the procedure. (Class of recommendation IIa Level of evidence B) If thrombus is found, 3 weeks of anticoagulant therapy prior and 4 weeks afterwards is a must. (Class of recommendation IIa Level of evidence C)

Don't

• Do not wait to give anticoagulants in a patient with hemodynamic instability, perform cardioversion immediately. Administer IV unfractionated heparin or SC injection of a low-molecular-weight heparin.
• Don't use digoxin as a single agent for rate control in patients with paroxysmal AF. (Class of recommendation III Level of evidence B)
• Do not attempt catheter ablation unless a trial of medication to control ventricular rate has been made. (Class of recommendation 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 of recommendation III Level of evidence A)
• Do not start quinidine, procainamide, disopyramide, and dofetilide in out of hospital setting. (Class of recommendation III Level of evidence B)
• Do not perform repeated electric cardioversion in those with short periods of normal sinus rhythm in between. (Class of recommendation III Level of evidence C)
• Do not perform electric cardioversion in those with digitalis toxicity and/or hypokalemia. (Class of recommendation III Level of evidence C)
• Don't use calcium channel blocker, beta blocker, and digoxin in atrial fibrillation patients with WPW.

References

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