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]

Definitions

Atrial fibrillation (AF or Afib) is a supraventricular tachyarrhythmia, characterized by uncoordinated atrial activation and improper atrio-ventricular mechanical function.

Primary AF is classified as shown below:

Term	Definition
Paroxysmal	AF lasting < 7 days (most last < 24 hours). Usually self terminating.
Persistent	AF lasting > 7 days. Usually does not terminate on its own.
Permanent	AF lasting for a longer period, where in 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.

• Congestive heart failure
• Dehydration
• Electrolyte disturbance
• Hypothermia
• Hypoxia
• Myocardial infarction
• Myocarditis
• Pericarditis
• Pheochromocytoma
• Pulmonary embolism
• Uremic pericarditis

Common Causes

• Coronary artery disease
• Hypertensive heart disease
• Rheumatic heart disease

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 ❑ Duration ❑ Frequency
		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

Newly Discovered Atrial Fibrillation

Shown below is an algorithm depicting the pharmacological management of patients with newly discovered atrial fibrillation:

Newly discovered AF

Paroxysmal AF

Persistent AF

❑ Look for the presence of one of these severe symptoms: ❑ Hypotension ❑ Heart failure ❑ Angina pectoris Severe symptoms absent: ❑ No therapy needed Severe symptoms present: ❑ Attempt direct-current cardioversion

Anticoagulation: ❑ Consider anticoagulation as needed based on the risk of stroke ❑ Click here for the risk of stroke and anticoagulation therapy Heart rate control: ❑ Control heart rate as an initial method to manage AF, and regulate ventricular output Click here for pharmacological agents and doses used to control heart rate

Anticoagulation: ❑ Consider anticoagulation as needed based on the risk of stroke ❑ Click here for the risk of stroke and anticoagulation therapy ❑ Recommended in all cases except lone AF (I A) ❑ Measure INR weekly initially, then monthly when stable (I A) ❑ Reassess need for anticoagulation at periodic intervals (IIa C)

Antiarrhythmic therapy: ❑ Consider antiarrhythmic therapy for maintenance of sinus rhythm Click here for recommended pharmacological agents used for maintenance of sinus rhythm

Cardioversion: ❑ Attempt cardioversion ❑ Click here for drugs and doses used for pharmacologic cardioversion ❑ If patient hemodynamically unstable or tachycardic, attempt electric cardioversion ❑ If pharmacological cardioversion fails, attempt electric cardioversion

❑ Do not treat with long term antiarrhythmic therapy, unless indicated.

Recurrent Paroxysmal Atrial Fibrillation

Shown below is an algorithm depicting the pharmacological management of patients with recurrent paroxysmal atrial fibrillation:

[[Atrial fibrillation resident survival guide#Definitions|Recurrent paroxysmal AF]]

Minimal or no symptoms

Disabling symptoms in AF

Anticoagulation: ❑ Consider anticoagulation as needed based on the risk of stroke ❑ Click here for the risk of stroke and anticoagulation therapy Heart rate control: ❑ Control heart rate as an initial method to manage AF, and regulate ventricular output Click here for pharmacological agents and doses used to control heart rate

Anticoagulation: ❑ Consider anticoagulation as needed based on the risk of stroke ❑ Click here for the risk of stroke and anticoagulation therapy Heart rate control: ❑ Control heart rate as an initial method to manage AF, and regulate ventricular output Click here for pharmacological agents and doses used to control heart rate

❑ Long term therapy for prevention of AF not needed

Antiarrhythmic therapy: ❑ Consider antiarrhythmic therapy for maintenance of sinus rhythm Click here for recommended pharmacological agents used for maintenance of sinus rhythm

❑ Consider AF ablation if antiarrhythmic drug treatment fails

Recurrent Persistent Atrial Fibrillation

Shown below is an algorithm depicting the pharmacological management of patients with recurrent persistent atrial fibrillation:

Recurrent persistent AF

Minimal or no symptoms

Disabling symptoms in AF

Anticoagulation: ❑ Consider anticoagulation as needed based on the risk of stroke ❑ Click here for the risk of stroke and anticoagulation therapy Heart rate control: ❑ Control heart rate as an initial method to manage AF, and regulate ventricular output Click here for pharmacological agents and doses used to control heart rate

Anticoagulation: ❑ Consider anticoagulation as needed based on the risk of stroke ❑ Click here for the risk of stroke and anticoagulation therapy Heart rate control: ❑ Control heart rate as an initial method to manage AF, and regulate ventricular output Click here for pharmacological agents and doses used to control heart rate

Antiarrhythmic therapy: ❑ Consider antiarrhythmic therapy for maintenance of sinus rhythm Click here for recommended pharmacological agents used for maintenance of sinus rhythm

❑ Perform electrical cardioversion as needed ❑ Pretreat with one of the following agents to reduce the risk of early recurrence of AF after cardioversion: ❑ Amiodarone ❑ Flecainide ❑ Ibutilide ❑ Propafenone ❑ Sotalol

❑ Continue anticoagulation therapy based on risk factor profile as above ❑ Continue antiarrhythmic therapy to maintain sinus rhythm as above

❑ Consider ablation for severely symptomatic recurrent AF after failure of ≥ 1 antiarrhythmic drug plus rate control

Permanent Atrial Fibrillation

Shown below is an algorithm depicting the pharmacological management of patients with permanent atrial fibrillation:

Permanent AF

Anticoagulation: ❑ Consider anticoagulation as needed based on the risk of stroke ❑ Click here for the risk of stroke and anticoagulation therapy Heart rate control: ❑ Control heart rate as an initial method to manage AF, and regulate ventricular output Click here for pharmacological agents and doses used to control heart rate

Antiarrhythmic Drug Therapy in Atrial Fibrillation

Shown below is an algorithm depicting the antiarrhythmic drug therapy for maintain sinus rhythm in patients with recurrent paroxysmal or persistent atrial fibrillation:

Maintenance of sinus rhythm

No (or minimal) heart disease

Hypertension

Coronary artery disease

Heart failure

Dronedarone Flecainide Propafenone Sotalol

Substantial LVH

Dronedarone Dofetilide Sotalol

Amiodarone Dofetilide

Amiodarone Dofetilide

Catheter ablation

No

Yes

Amiodarone

Catheter ablation

Catheter ablation

Dronedarone Flecainide Propafenone Sotalol

Amiodarone

Catheter ablation

Amiodarone Dofetilide

Catheter ablation

Drugs are listed alphabetically and not in order of suggested use.
The seriousness of heart disease progresses from left to right, and selection of therapy in patients with multiple conditions depends on the most serious condition present.

Following table summarizes the list of most commonly used drugs and their dosages for maintenance of sinus rhythm:

Drug	Dose
Amiodarone	100 to 400 mg
Disopyramide	400 to 750 mg
Dofetilide	5000 to 1000 mcg
Flecainide	200 to 300 mg
Procainamide	1000 to 4000 mg
Propafenone	450 to 900 mg
Quinidine	600 to 1500 mg
Sotalol	160 to 320 mg

Pharmacological Cardioversion

Cardioversion upto7 Days

Drug	Dosage
Agents with proven efficacy
Dofetilide (I A)	Creatinine clearance(ml/min) Dose (mg) >60 500 40 to 60 250 20 to 40 125 <20 Contraindicated
Flecainide (I A)	Oral: 200 to 300 mg Intravenous: 1.5 to 3.0 mg/kg over 10 to 20 min
Ibutilide (I A)	1 mg over 10 min; repeat 1 mg when necessary
Propafenone (I A)	Oral: 600 mg Intravenous: 1.5 to 2.0 mg/kg over 10 to 20 min
Amiodarone (IIa 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
Dofetilide (I A)	Creatinine clearance(ml/min) Dose (mg) >60 500 40 to 60 250 20 to 40 125 <20 Contraindicated
Amiodarone (IIa 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.
Ibutilide (IIa A)	1 mg over 10 min; repeat 1 mg when necessary

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

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

Risk Category	Recommended 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)*

Pharmacological Agents for Heart Rate Control

Drug	Loading Dose	Maintenance Dose
Acute Setting
Heart rate control in patients without accessory pathway
Esmolol (I C)	500 mcg/kg IV over 1 min	60 to 200 mcg/kg/min IV
Propanolol (I C)	0.15 mg/kg IV	NA
Metoprolol (I C)	2.5 to 5 mg IV bolus over 2 min; up to 3 doses	NA
Diltiazem (I B)	0.25 mg/kg IV over 2 min	5 to 15 mg/h IV
Verampil (I B)	0.075 to 0.15 mg/kg IV over 2 min	NA
Heart Rate Control in patients with accessory pathway
Amiodarone (IIa 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 (I B)	0.25 mg IV each 2 h, up to 1.5 mg	0.125 to 0.375 mg daily IV or orally
Amiodarone (IIa C)	150 mg over 10 min	0.5 to 1 mg/min IV
Non-Acute Setting and Chronic Maintenance Therapy
Heart rate control
Metoprolol (I C)	Same as maintenance dose	25 to 100 mg twice a day, orally
Propanolol (I C)	Same as maintenance dose	80 to 240 mg daily in divided doses, orally
Verampil (I B)	Same as maintenance dose	120 to 360 mg daily in divided doses; slow release available, orally
Diltiazem (I B)	Same as maintenance dose	120 to 360 mg daily in divided doses; slow release available, orally
Heart Rate Control in patients with heart failure and without accessory pathway
Digoxin (I C)	0.5 mg by mouth daily	0.125 to 0.375 mg daily, orally
Amiodarone (IIb 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

Therapeutic agents for Atrial fibrillation

• No mortality benefit is evident from rhythm control over rate control.
• Rate control with beta blockers (metoprolol/lopressor, atenolol/tenormin) or non-dihydropyridine calcium channel blockers (diltiazem/cardizem, verapamil)is recommended in older patients with chronic AF or unknown duration. Digoxin can be used as a second line drug.
• For young symptomatic AF patients rhythm control is preferred over rate control. Rhythm control can be achieved by medications, synchronized cardioversion or both. If both these options fail, catheter based ablation is an option.
• Sotalol and Dofetelide - monitor QTc interval for prolongation for 48 hrs post initiation. QTc >= 500 or 15% above baseline may increase the risk of Torsades. Check daily EKG or EKG 2 hours post the drug dose.
• Amiodarone can cause bradycardia, hepatotoxicity, throtoxicity, pulmonary fibrosis, and retinopathy.
• Flecanide should be used with beta blockers as it may increases the risk of rapid AV nodal conduction. It also increases digoxin levels
• Hemodynamic stability is first priority, rate or rhythm control 2nd.
• Hypotension could be rate related so treatment should not be avoided.

Cardioversion

• Emergent cardioversion for hemodynamically unstable AF.
• If drug therapy fails, cardioversion with 100 joules of electricity is recomended.
• Prior to an elective cardioversion in patients who have been in AF > 48hrs or unknown duration, either a negative TEE or 3-4 weeks of anticoagulation is recommended.
• Post cardioversion 4 weeks of anticoagulation is recommended.

Don't

• Don't use Digoxin as a single agent for rate control.
• Don't use calcium channel blocker, beta blocker, and digoxin in atrial fibrillation patients with WPW

References

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