Atrial fibrillation resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Hilda Mahmoudi M.D., M.P.H.^[2]; Vidit Bhargava, M.B.B.S [3]; Priyamvada Singh, M.D. [4]; Rim Halaby, M.D. [5]; Mugilan Poongkunran M.B.B.S [6]

Atrial fibrillation resident survival guide Microchapters
Overview
Classification
Causes
FIRE
Complete Diagnostic Approach
Treatment New Onset AFib Recurrent AFib Permanent AFib
Rate Control Strategy
Maintenance of Sinus Rhythm
Cardioversion Strategy
Anticoagulation Strategy
Do's
Dont's

Overview

Atrial fibrillation (AF) is a supraventricular tachyarrhythmia characterized by uncoordinated atrial activation leading to an irregularly irregular rhythm and absent P waves on ECG. It is characterized by palpitations, dyspnea, chest discomfort, syncope, etc. and can be triggered by a number of conditions. It can be a serious life threatening disorder as the irregular atrial rhythm with rate of 400-700 beats/min may transpire into a rapid ventricular rhythm eventually leading to ventricular failure. It can occur in a heart with underlying structural heart defect or in a structurally normal heart. Treatment of AF depends on hemodynamic status of the patient. If unstable, rapid DC cardioversion is attempted, otherwise rate control and anticoagulation are the treatment of choice, followed by antiarrhythmic therapy.

Classification

Paroxysmal Atrial Fibrillation

Atrial fibrillation is paroxysmal when it terminates within 7 days of onset (most frequently in less than 24 hours) either spontaneously or with intervention.

Persistent Atrial Fibrillation

Atrial fibrillation is persistent when it is continuous for more than 7 days.

Long Standing Persistent Atrial Fibrillation

Atrial fibrillation is long standing persistent when it continuous for more than 12 months.

Permanent Atrial Fibrillation

Atrial fibrillation is permanent when it lasts for a longer period and there has been a joint decision made by clinician and patient to cease all attempts to restore and/or maintain sinus rhythm.

Non-valvular Atrial Fibrillation

Atrial fibrillation in the absence of rheumatic mitral stenosis, a mechanical valve or bioprosthetic heart valve, or mitral valve repair.

Causes

Life Threatening Causes

Atrial fibrillation can be a life-threatening condition and must be treated as such irrespective of the underlying cause.

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

Click here for the complete list of causes.

FIRE: Focused Initial Rapid Evaluation

A Focused Initial Rapid Evaluation (FIRE) should be performed to identify patients in need of immediate intervention.

Boxes in red color signify that an urgent management is needed.

Abbreviations: EKG: Electrocardiogram; SBP: Systolic blood pressure

Identify cardinal findings that increase the pretest probability of atrial fibrillation: ❑ Palpitations ❑ Irregularly irregular pulse ❑ Heart rate > 100 beats/min ❑ Typical EKG findings: ❑ Lack of discrete P waves ❑ Variability in the intervals between QRS complexes ❑ Narrow QRS complexes ❑ Ventricular rate of 90 to 170 beats/min Absent P waves and irregularly irregular heart rate, suggestive of atrial fibrillation

Does the patient have any of the following findings that require urgent cardioversion? ❑ Hemodynamic instability ❑ Hypotension ❑ Cold extremities ❑ Peripheral cyanosis ❑ Mottling ❑ Altered mental status ❑ Acute ischemia ❑ Chest discomfort ❑ EKG findings for acute coronary syndrome ❑ Decompensated heart failure

Yes

No

Does the patient has any symptoms and signs of pulmonary edema? ❑ Dyspnea ❑ Crackles ❑ Chest X-ray (pulmonary edema)

Proceed with the complete diagnostic approach below

Yes

No

Manage pulmonary edema: ❑ Initiate oxygen therapy ❑ High dose IV diuretics ❑ BP management ❑ SBP 85 - 100 mm Hg (dobutamine or milrinone) :❑ SBP < 85 mm Hg (dopamine and norepinephrine)

Immediate DC cardioversion ❑ 120-200 Joules biphasic or 200 Joules monophasic

After initial pulmonary edema management proceed with DC cardioversion

Successful

Unsuccessful

After stabilization proceed with the complete diagnostic approach below

Repeat cardioversion ❑ Adjust the location of the electrodes ❑ Apply pressure over the electrodes ❑ May proceed after a trial of antiarrhythmic medication

After stabilization proceed with the complete diagnostic approach below

Complete Diagnostic Approach to Atrial Fibrillation

A complete diagnostic approach should be carried out after a focused initial rapid evaluation is conducted and following initiation of any urgent intervention.

Abbreviations: AF: Atrial fibrillation; COPD: Chronic obstructive pulmonary disease; EKG: Electrocardiogram; MI: Myocardial infarction; TSH: Thyroid stimulating harmone

Characterize the symptoms: ❑ Asymptomatic ❑ Palpitations ❑ Fatigue ❑ Lightheadedness ❑ Mild shortness of breath ❑ Increased urination ❑ Severe dyspnea ❑ Chest discomfort (suggestive of angina or MI) ❑ Presyncope/ syncope ❑ Abdominal distension (suggestive of right heart failure) ❑ Leg swelling (suggestive of right heart failure) ❑ Weakness (suggestive of an embolic event) ❑ Hemoptysis (suggestive of an embolic event) Characterize the timing of the symptoms: ❑ Onset ❑ First episode ❑ Recurrent ❑ Duration ❑ Frequency ❑ Termination of the episode ❑ Spontaneous ❑ Medication use ❑ Not terminated

Obtain a detailed history: Common disease associations: ❑ Hypertensive heart disease ❑ Coronary heart disease ❑ Valvular heart disease ❑ Heart failure ❑ Congenital heart disease ❑ Cardiac surgery ❑ Hyperthyroidism ❑ Cardiac tamponade ❑ Pulmonary embolism ❑ Infection ❑ Coronary thrombosis ❑ Trauma Medications: ❑ Theophylline ❑ Adenosine ❑ Digitalis ❑ Bisphosphonates Identify possible triggers: ❑ Caffeine ❑ Alcohol ❑ Nicotine ❑ Recreational drugs ❑ Hypovolemia ❑ Acidosis ❑ Hypokalemia ❑ Hyperkalemia ❑ Hypoglycemia ❑ Hypothermia ❑ Toxins ❑ Hypoxia

Examine the patient: Vital signs: ❑ Pulse ❑ Tachycardia ❑ Irregularly irregular (typical) ❑ Blood pressure ❑ Hypertension ❑ Hypotension (suggestive of ventricular dysfunction) ❑ Narrow pulse pressure (suggestive of congestive heart failure) ❑ Respiratory rate ❑ Tachypnea Skin: ❑ Diaphoresis ❑ Peripheral edema (suggestive of right heart failure) Cardiovascular system: ❑Tachycardia ❑ Any murmur (suggestive of valvular heart disease) ❑ Jugular vein distention ❑ Flutter waves in jugular vein ❑ Third heart sound (suggestive of heart failure) ❑ Gallop rhythm Respiratory system: ❑ Crackles (suggestive of pulmonary edema) ❑ Hyperresonance/hyperinflation/wheeze (suggestive of COPD) Eye: ❑ Exopthalmos (suggestive of hyperthyroidism) ❑ Retinal hemorrhage (suggestive of malignant hypertension) Neck: ❑ Thyroid enlargement Neurological system: ❑ Stroke (in case of thromboembolism) Signs of embolization: ❑ Cold extremities ❑ Loss of distal pulsations ❑ Pallor of the extremity ❑ Muscle pain/spasm in concerned area ❑ Weakness/lack of movement ❑ Tingling and numbness 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 EKG ❑ Left ventricular hypertrophy ❑ Preexcitation ❑ Bundle branch block ❑ Previous myocardial infarction ❑ Other types of arrhythmias

Order blood tests: (if AF has not been investigated before) ❑ Complete blood count ❑ Serum glucose ❑ Serum electrolytes ❑ TSH and free T4 ❑ Serum BUN and creatinine ❑ Coagulation studies (INR/aPTT) ❑ Serum cardiac troponin I and T (in case of acute-onset AF associated with chest pain) Order imaging studies: ❑ Order a chest X-ray ❑ Cardiogenic pulmonary edema ❑ Cardiomegaly ❑ To detect any pulmonary cause (COPD/pneumonia) ❑ Order a TTE or TEE ❑ To evaluate the size of the right and left atria ❑ To detect possible valvular heart disease ❑ To identify thrombi in the left atrium or left atrial appendage Other tests: ❑ Holter monitor ❑ If arrhythmia is intermittent and not captured on routine EKG ❑ Exercise Stress Testing ❑ To exclude ischemia before treatment of selected patients with a type IC antiarrhythmic drug ❑ To reproduce exercise induced AF ❑ If the adequacy of rate control is in question (permanent AF)

New onset paroxysmal AF ❑ First Episode ❑ Lasts less than 7 days ❑ Usually self terminating

New onset persistent AF ❑ First Episode ❑ Lasts more than 7 days ❑ Doesn't terminate on its own

Recurrent paroxysmal AF ❑ Previous history of AF ❑ Lasts less than 7 days ❑ May or may not be self terminating

Recurrent persistent AF ❑ Previous history of AF ❑ Lasts more than 7 days ❑ Needs medical or surgical management

Permanent AF ❑ Fibrillation present continuously ❑ Needs constant management

Treatment

New Onset Atrial Fibrillation

Shown below is an algorithm depicting the management of patients with newly discovered atrial fibrillation based on the 2014 ACCF/AHA/HRS Guideline for the Management of Patients With Atrial Fibrillation.

Abbreviations: AF: Atrial fibrillation; BP: Blood pressure; bpm: Beats per minute; DC: Direct current; EF: Ejection fraction; HR: Heart rate; SBP: Systolic blood pressure

New onset atrial fibrillation (Paroxysmal or persistent or permanent)

Stable: ❑ Asymptomatic OR ❑ Mild to moderate symptoms

Unstable: ❑ Hypotension ❑ Tachycardia ❑ Cold extremities ❑ Peripheral cyanosis ❑ Mottling ❑ Altered mental status ❑ Ongoing ischemia ❑ Decompensated heart failure

Does the patient require heart rate control therapy?

Does the patient has any symptoms and signs of pulmonary edema? ❑ Dyspnea ❑ Crackles ❑ Chest X-ray showing pulmonary edema

No (spontaneous cardioversion)

Yes

Yes

No

❑ Identify the underlying etiology and treat accordingly ❑ Proceed with anticoagulation strategy as shown below

❑ Proceed with the heart rate control strategy

Manage pulmonary edema: ❑ Initiate oxygen therapy ❑ High dose IV diuretics ❑ BP management ❑ SBP 85 - 100 mm Hg (dobutamine or milrinone) ❑ SBP < 85 mm Hg (dopamine and norepinephrine)

Immediate DC cardioversion

Did the patient achieve heart rate control goal: ❑ Resting HR <110 bpm in asymptomatic and EF > 40% patients ❑ Resting HR <80 bpm in symptomatic and EF < 40% patients

After initial pulmonary edema management proceed with DC cardioversion

Yes

No

Successful

Unsuccessful

❑ Identify the underlying etiology and treat accordingly ❑ Proceed with cardioversion strategy for initial symptomatic patients as shown below ❑ Proceed with anticoagulation strategy as shown below

❑ Identify the underlying etiology and treat accordingly ❑ Proceed with cardioversion strategy as shown below ❑ Proceed with anticoagulation strategy as shown below

Identify the underfying cause and treat accordingly

Repeat cardioversion: ❑ After adjusting the location of the electrodes and applying pressure over the electrodes OR ❑ After administration of an antiarrhythmic medication

Proceed with the anticoagulation strategy

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 Atrial Fibrillation

Shown below is an algorithm depicting the management of patients with recurrent atrial fibrillation based on the 2014 ACCF/AHA/HRS Guideline for the Management of Patients With Atrial Fibrillation.

Abbreviations: AF: Atrial fibrillation; bpm: Beats per minute; DC: Direct current; EF: Ejection fraction; HR: Heart rate

Recurrent atrial fibrillation (Paroxysmal or persistent)

Asymptomatic

Symptomatic

❑ Identify the underlying etiology and treat accordingly ❑ Proceed with heart rate control strategy as shown below

❑ Identify the underlying etiology and treat accordingly ❑ Proceed with heart rate control strategy as shown below

Did the patient achieve heart rate control goal: ❑ Resting HR <110 bpm in asymptomatic and EF > 40% patients ❑ Resting HR <80 bpm in symptomatic and EF < 40% patients

Did the patient achieve heart rate control goal: ❑ Resting HR <110 bpm in asymptomatic and EF > 40% patients ❑ Resting HR <80 bpm in symptomatic and EF < 40% patients

Yes

No

No

Yes

❑ Initiate long term rate control strategy ❑ Proceed with anticoagulation strategy as shown below

❑ Proceed with the cardioversion strategy

❑ Proceed with the cardioversion strategy

❑ Initiate antiarrhythmic drug therapy for maintenance of sinus rhythm ❑ Proceed with anticoagulation strategy as shown below

Successful (sinus rhythm)

Unsuccessful (AF)

❑ Initiate antiarrhythmic drug therapy for maintenance of sinus rhythm ❑ Proceed with anticoagulation strategy as shown below

❑ Initiate long term rate control strategy ❑ Proceed with anticoagulation strategy as shown below ❑ Consider catheter ablation

Permanent Atrial Fibrillation

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

Permanent AF
❑ Initiate long term rate control strategy ❑ Proceed with anticoagulation strategy as shown below

Rate Control Strategy

Shown below is an algorithm depicting the management of ventricular rate in patients with atrial fibrillation based on the 2014 ACCF/AHA/HRS Guideline for the Management of Patients With Atrial Fibrillation.

Abbreviations: AF: Atrial fibrillation; bpm: Beats per minute; COPD: Chronic obstructive pulmonary disease; CVD: Cardiovascular disease; EF: Ejection fraction; HF: Heart failure; HFpEF: Heart failure with preserved ejection fraction; HFrEF: Heart failure with reduced ejection fraction; HR: Heart rate; LV: Left ventricle

Stable AF patients requiring heart rate control therapy

Heart rate control goal: ❑ Resting HR <110 bpm in asymptomatic and EF > 40% patients ❑ Resting HR <80 bpm in symptomatic and EF < 40% patients

Does the patient have any evidence of an accessory pathway (pre-excitation syndrome)?

NO

YES

COPD

HFrEF or LV dysfunction

Hypertension or HFpEF or No CVD

❑ Nondihydropyridine calcium channel blockers: Most preferred OR ❑ Beta blockers: Cardioselective ❑ Oral vs IV according to the clinical urgency

❑ Beta blockers: After stabilization in patients with decompensated HF OR ❑ Digoxin ❑ Oral vs IV according to the clinical urgency

❑ Beta blockers OR ❑ Nondihydropyridine calcium channel blockers ❑ Oral vs IV according to the clinical urgency

❑ Procainamide OR ❑ Ibutilide ❑ Oral vs IV according to the clinical urgency

❑ Amiodarone ❑ Oral vs IV according to the clinical urgency

Consider catheter ablation if the accessory pathway has a short refractory period that allows rapid antegrade conduction

Rate Control Drugs & Dosages

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

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 2011 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

Drugs & Dosages

Shown below is a table summarizing the list of recommended agents for maintenance of sinus rhythm and their dosages.

Maintenance of sinus rhythm Drug Dose Avoid or Use with caution ▸ Disopyramide ▸ Immediate release: 100-200 mg QID ▸ Extended release: 200-400 mg BID HF Prolonged QT interval Prostatism Glaucoma Avoid other QT interval-prolonging drugs ▸ Quinidine ▸ 324-648 mg TID Prolonged QT interval Diarrhea ▸ Flecainide ▸ 350-200 mg BID Sinus or AV node dysfunction HF CAD Atrial flutter Infranodal conduction ▸ Propafenone ▸ Immediate release: 150-300 mg TID ▸ Extended release: 225-425 mg BID Sinus or AV node dysfunction HF CAD Atrial flutter Infranodal conduction Brugada syndrome Liver disease Asthma ▸ Amiodarone ▸Oral: 400-600 mg daily in divided doses for 2-4 wk; maintenance typically 100-200 mg QD IV: 150 mg over 10 min; then 1 mg/min for 6 h; then 0.5 mg/min for 18 h or change to oral dosing; after 24 h, consider decreasing dose to 0.25 mg/min Sinus or AV node dysfunction Infranodal conduction Prolonged QT interval ▸ Dofetilide ▸ 125-500 mcg BID Prolonged QT interval Renal disease Hypokalemia Diuretic therpay Avoid other QT interval-prolonging drugs ▸ Dronedarone ▸ 400 mg BID Bradycardia HF Long-standing or persistent AF/flutter Liver disease Prolonged QT interval ▸ Sotalol ▸ 40-160 mg BID Prolonged QT interval Renal disease Hypokalemia Diuretic therapy Avoid other QT interval prolonging drugs Sinus or AV nodal dysfunction HF Asthma

Cardioversion Strategy

Shown below is an algorithm depicting the cardioversion treatment in patients with atrial fibrillation.

Abbreviations: AF: Atrial fibrillation; LA: Left atrium; TEE: Transesophageal echocardiogram

Choice of Cardioversion

Does the patient have any signs of hemodynamic instability

No

Yes

Recurrent paroxysmal or persistent AF

New onset AF

No structural heart disease

Structural heart disease

Pharmacological cardioversion

DC cardioversion

Pharmacological cardioversion

DC cardioversion

DC Cardioversion Strategy

Does the patient with AF has any contraindication for cardioversion : ❑ Asymptomatic elderly patients (>80 years) with multiple comorbidities ❑ Patients with high risk of bleeding

No

Yes

Anticoagulation strategy

❑ <48 hours

❑ >48 hours ❑ Unknown duration ❑ Prior history of a thromboembolism ❑ Prior history of TEE evidence of left atrial thrombus ❑ Mitral valve disease or significant cardiomyopathy or heart failure

❑ IV heparin

❑ 3 week oral anticoagulation

❑ TEE

❑ Cardioversion

No LA thrombus

LA thrombus

Sinus rhythm

Atrial fibrillation

❑ IV heparin

❑ 3 week oral anticoagulation

❑ Initiate 4 week anticoagulation therapy after cardioversion

Repeat TEE showing no LA thrombus

Repeat TEE showing LA thrombus

Cardioversion

❑ Initiate rate control & proceed with other management

Atrial fibrillation

Sinus rhythm

❑ Repeat cardioversion or use AV nodal blocking agents

❑ 4 week anticoagulation after cardioversion

Sinus rhythm

Atrial fibrillation

❑ Initiate 4 week anticoagulation therapy

❑ Initiate 4 week anticoagulation therapy ❑ Proceed with other management

Pharmacological Cardioversion Drugs & Dosages

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

Anticoagulation Strategy

Shown below is an algorithm depicting the assessment of risk of stroke and the appropriate anticoagulation therapy among patients with AF.

Abbreviations: AF: Atrial fibrillation; BID: Twice daily; CrCL: Creatinine clearance; INR: International normalized ratio; QD: Once daily

Assess the absolute and relative risk of bleeding before initiating long term anticoagulation

Non-valvular AF

AF with valvular heart disease

AF with mechanical heart valves

Assess CHA2DS2-VASc scoring risk

Score 0

Score 1

Score ≥ 2

No antithrombotic therapy

No antithrombotic therapy or may consider an oral anticoagulant or aspirin

Oral antithrombotic therapy: ❑ Warfarin: ❑ Target INR 2-3 ❑ INR determined weekly before stabilization ❑ Dabigatran, or rivaroxaban, or apixaban: ❑ Evaluate renal function before initiation ❑ Dont use apixaban in patients with severe hepatic impairment

Oral antithrombotic therapy: ❑ Warfarin: ❑ Target INR 2-3 ❑ INR determined weekly before stabilization

Oral antithrombotic therapy: ❑ Warfarin: ❑ Target INR 2-3 or 2.5-3.5 based on type and location of valve ❑ Caution: ❑ Dont use direct thrombin inhibitor and dabigatran

Does the INR of patients on warfarin stabilize to the recommended value

Yes

No

Determine INR every month

Direct thrombin or factor Xa inhibitor: ❑ Dabigatran, rivaroxaban, or apixaban: ❑ Evaluate renal function before initiation ❑ Caution: ❑ Dont use in patients with end-stage CKD or on hemodialysis

Determine INR weekly before stabilization and then every month

Note: For patients with AF undergoing procedures that require interruption of warfarin bridging therapy with unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) is needed.

Oral Anticoagulant Drugs and Dosages

Shown below is a table summarizing the list of recommended oral anticoagulant drugs and their dosages.

Renal function Dabigatran Rivaroxaban Apixaban ▸ Normal or mild impairment ▸ 150 mg BID ▸ 20 mg QD with the evening meal ▸ 5.0 or 2.5 mg BID ▸ Moderate impairment (CrCl >30 mL/min) ▸ 150 or 75 mg BID ▸ 15 mg QD with the evening meal ▸ 5.0 or 2.5 mg BID ▸ Severe impairment (CrCl 15-30 mL/min) ▸ 75 mg BID ▸ 15 mg QD with the evening meal ▸ No recommendation ▸ End-Stage CKD on/not dialysis (CrCl <15 mL/min) ▸ Not recommended ▸ Not recommended ▸ Not recommended

Note: Warfarin dose is adjusted for an of INR 2.0-3.0 in patients with any severity of the renal impairment.

CHA2DS2-VASc Scoring System

CHA2DS2-VASc Variable Score ▸ Age ≥75 years ▸ 2 ▸ Age 65-74 years ▸ 1 ▸ Female sex ▸ 1 ▸ Diabetes mellitus ▸ 1 ▸ Hypertension ▸ 1 ▸ Congestive heart failure ▸ 1 ▸ Stroke/TIA/Thromboembolism ▸ 2 ▸ Vascular disease (prior MI, PAD, or aortic plaque) ▸ 1

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).

• Consider 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 at least 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 cardioversion 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.
• Do not initiate rhythm control strategy when AF becomes permanent.
• Do not administer dronedarone to control the ventricular rate in patients with permanent AF or to patients with NYHA class III and IV HF or patients who have had an episode of decompensated HF in the past 4 weeks.
• Do not initiate dofetilide therapy out of hospital owing to the risk of excessive QT prolongation.

References

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