Best Dx/Best Rx: Atrial Fibrillation

From: Subject: Best Dx/Best Rx: Atrial Fibrillation Date: Wed, 3 Jun 2009 23:00:32 -0700 MIME-Version: 1.0 Content-Type: multipart/related; type="text/html"; boundary="----=_NextPart_000_006E_01C9E49F.1900B6E0" X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 This is a multi-part message in MIME format. ------=_NextPart_000_006E_01C9E49F.1900B6E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Location: mhtml:file://C:\pocketnotes\afib2006.mht Best Dx/Best Rx: Atrial Fibrillation

Atrial = Fibrillation=20

Anthony Aizer, M.D.
Valentin=20 Fuster, M.D., Ph.D.
Mount Sinai School of Medicine

Defin= ition/Key=20 Clinical Features
Diffe= rential=20 Diagnosis
Best = Tests
Best = Therapy
Best = References

Definition/Key=20 Clinical Features

A supraventricular tachyarrhythmia defined by = rapid,=20 irregular atrial activation=20
Most common sustained arrhythmia=20
- Incidence ~ 0.1%/yr=20
- Incidence increases with age (affects one = out of 11=20 persons > 80 yr in U.S.)=20
- Occurs after 25% of all coronary bypass = surgeries and=20 after 60% of combined coronary bypass and mitral valve = surgeries=20
- Independent predictor of mortality and = stroke after=20 acute MI=20
- Life-threatening when associated with=20 Wolff-Parkinson-White syndrome=20
- May be caused by thyrotoxicity; associated = with=20 increased risk of stroke=20
- High risk of death and stroke when = associated with=20 hypertrophic cardiomyopathy=20
- May be initiated by hypoxia and other = metabolic=20 disturbances in pulmonary disease
May occur with other arrhythmias=97notably, = atrial=20 flutter=20
Variable clinical manifestations=20
- Asymptomatic but with irregular pulse =
- Stroke=20
- Palpitations=20
- Fatigue=20
- Dyspnea=20
- Reduced exercise capacity=20
- Chronic heart failure (CHF)=20
- Angina=20
- Presyncope or syncope=20
- Thromboembolism=20
- Tachycardia-induced cardiomyopathy=20

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Differential = Diagnosis

Classification=20
- Recurrent: atrial fibrillation (AF) = occurring in a=20 patient who has experienced an episode of AF in the past=20
- Lone: AF occurring in a patient < 60 yr = who has no=20 clinical or echocardiographic evidence of cardiopulmonary = disease=20
- Valvular or nonvalvular=20
  - Valvular: AF in a patient who has evidence = or=20 history of rheumatic mitral valve disease or has a prosthetic = valve=20
  - Nonvalvular: all other forms =
- Paroxysmal: AF that typically lasts ≤ = 7 days and that=20 converts spontaneously to sinus rhythm=20
- Persistent: AF that typically lasts > 7 = days or=20 requires pharmacologic or direct current (DC) cardioversion
- Permanent: AF that is refractory to = cardioversion or=20 that has persisted > 1 yr

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Best=20 Tests

Laboratory tests=20
- Thyroid function tests=20
  - Reassess if ventricular rate difficult to = control or=20 if AF recurs unexpectedly after conversion to sinus rhythm =
- Serum electrolytes=20
- Hemoglobin or hematocrit =
ECG=20
- AF verification=20
- P-wave morphology (atrial flutter)=20
- Preexcitation=20
- Atrial arrhythmias other than AF, as = possible AF=20 triggers=20
- Left ventricular hypertrophy (hypertension,=20 hypertrophic cardiomyopathy)=20
- Bundle branch block or previous MI (coronary = artery=20 disease [CAD], left ventricular dysfunction, conduction system=20 disease)=20
- RR, QRS, QT intervals (to guide arrhythmic = drug=20 therapy)
Imaging=20
- Chest radiography=20
  - Intrinsic lung disease=20
  - Abnormal pulmonary vasculature, for = pulmonary=20 hypertension=20
  - Cardiac size and shape (CHF, pericardial=20 disease)
- Transthoracic echocardiography=20
  - Left and right atrial size and = function=20
  - Left ventricular size, function, and=20 hypertrophy=20
  - Valvular heart disease, including = rheumatic heart=20 disease=20
  - Right ventricular systolic pressure, for = pulmonary=20 hypertension=20
  - Left atrial thrombus=20
  - Spontaneous echocardiographic contrast = (low=20 sensitivity)=20
  - Pericardial disease=20
  - Aortic plaque (low sensitivity)=20
Additional testing=20
- Event and Holter monitors=20
- Documentation of infrequent symptomatic = episodes where=20 AF not confirmed previously=20
- Therapeutic follow-up of rate control =
Exercise testing=20
- Confirm presence of ischemic heart = disease=20
- Unmask exercise-mediated AF=20
- Evaluate safety of specific = medications=20
- Assess rate control
Transesophageal echocardiography (TEE)=20
- Establish risk of embolic stroke=20
  - Left atrial and left atrial appendage=20 thrombus=20
  - Left atrial and left atrial appendage = spontaneous=20 echo contrast=20
  - Left atrial appendage flow velocity =
  - Aortic plaque
Electrophysiologic study=20
- Define specific forms of AF amenable to = catheter-based=20 intervention=20
- Assess underlying conduction system etiology = of=20 wide-complex tachycardias

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Best=20 Therapy

Newly Discovered AF

Paroxysmal=20
- No therapy unless symptoms severe (e.g., = hypotension,=20 CHF, angina)=20
- Anticoagulation as needed
Persistent=20
- Rate control and anticoagulation as = needed=20
  - Consider antiarrhythmic drug = therapy=20
  - Cardioversion=20
  - Long-term antiarrhythmic drug therapy=20 unnecessary
- Accept permanent AF=20
  - Anticoagulation and rate control as = needed=20

Recurrent = Paroxysmal=20 AF=20

Minimal or no symptoms=20
- Anticoagulation and rate control as = needed=20
- No drug therapy for prevention of AF =
Disabling symptoms when in AF=20
- Anticoagulation and rate control as = needed=20
- Antiarrhythmic drug therapy=20

Recurrent Persistent = AF=20

Minimal or no symptoms=20
- Anticoagulation and rate control as = needed=20
Disabling symptoms when in AF=20
- Anticoagulation and rate control=20
- Antiarrhythmic drug therapy=20
- Electrocardioversion as needed=20
- Continue anticoagulation as needed and = therapy to=20 maintain sinus rhythm

Permanent AF=20

Anticoagulation and rate control as = needed=20

Drug Therapy=20

Drugs for Cardioversion of Atrial = Fibrillation and=20 Maintenance of Sinus Rhythm=20

Considerations in pharmacologic = cardioversion=20
- Acute conversion rather than rate control if = patient=20 hemodynamically unstable with angina, CHF, symptomatic hypotension, = acute=20 MI=20
- Lower success rate than with electrical=20 cardioversion=20
- Risk of life-threatening arrhythmias=20
- Efficacy typically declines as duration of = AF=20 increases
Considerations in pharmacologic maintenance of = sinus=20 rhythm=20
- Amiodarone and dofetilide first-line therapy = in=20 patients with CHF=20
- Amiodarone first choice if LVH with left = ventricular=20 wall thickness ≥ 14 mm=20
- Sotalol safe for use in patients with = implantable=20 cardioverter defibrillators (ICDs)=20
- Agents with beta-blocking properties = preferred in=20 patients with CAD
Follow-up monitoring=20
- ECG=20
  - Necessary in all patients on = antiarrhythmic=20 medication=20
  - Exercise ECG within 3 days of starting = flecainide or=20 propafenone; monitor for QRS widening
- Serum potassium and magnesium=20
- Renal function
Amiodarone=20
- Toxicity: bradycardia, visual disturbances, = nausea,=20 constipation, phlebitis (I.V.); hepatic, ocular, pulmonary, thyroid, = neurologic toxicity=20
- Hours to weeks for cardioversion=20
- Safe in patients with left ventricular=20 dysfunction=20
- Torsade de pointes (TdP)/ventricular = tachycardia (VT)=20 less common than with dofetilide, ibutilide, or sotalol=20
- Dose for cardioversion=20
  - Oral, inpatient: 1.2=961.8 g/day in = divided doses=20 until 10 g total, then 200=96400 mg/day maintenance; or 30 mg/kg = single=20 dose=20
  - Oral, outpatient: 600=96800 mg/day in = divided doses=20 until 10 g total=20
  - Intravenous/oral: 5=967 mg/kg over 30=9660 = min, then=20 1.2=961.8 g/day continuous I.V. or divided oral doses until 10 g=20 total
- Dose for maintenance of sinus rhythm: = 100=96400 mg=20 q.d.=20
  - Cost/mo: $58
Dofetilide=20
- Days to weeks for cardioversion=20
- Safe in patients with left ventricular=20 dysfunction=20
- Dose for cardioversion (for specified = creatinine=20 clearance, C_Cr)=20
  - 500 =B5g b.i.d. for C_Cr > 60 = ml/min=20
  - 250 =B5g b.i.d. for C_Cr 40=9660 = ml/min=20
  - 125 =B5g b.i.d. for C_Cr 20=9640 = ml/min=20
  - Contraindicated for C_Cr < 20 = ml/min
- Dose for maintenance of sinus rhythm: = 500=961,000 =B5g=20 q.d.=20
  - Dosage adjustment based on corrected QT = interval=20 (QT_C)
Ibutilide=20
- Used for cardioversion only; time to = cardioversion:=20 < 1 hr
- Monitor serum potassium and magnesium =
- Requires 4 hr of monitoring for TdP=20
- Safe in patients with left ventricular=20 dysfunction=20
- Dose: 1 mg I.V. over 10 min; repeat once if=20 necessary
Sotalol (toxicity: bradycardia)=20
- Used for maintenance of sinus rhythm = only=20
- Use with caution in patients with left = ventricular=20 dysfunction=20
- May exacerbate CHF, COPD=20
- Associated with TdP=20
- Dose: 240=96320 mg q.d.=20
  - Dosage adjustment based on = QT_c=20
  - Reduced dose with renal = insufficiency=20
  - Cost/mo: $147
Flecainide
- Time to cardioversion: 3 hr=20
- Pretreat with AV nodal blocking agents = (e.g.,=20 verapamil, diltiazem) to avoid accelerated ventricular = response=20
- Avoid in patients with CHF, left ventricular = dysfunction, or CAD=20
- Levels increased by amiodarone=20
- Dose for cardioversion: 200=96300 mg=20
- Dose for maintenance of sinus rhythm: = 200=96300 mg=20 q.d.=20
  - Reduced dose with renal = insufficiency=20
  - Cost/mo: $115
Propafenone
- Toxicity: blurred vision, hypotension=20
- Time to cardioversion: < 6 hr=20
- Efficacy reduced in patients with structural = heart=20 disease=20
- Increases digoxin and warfarin levels=20
- Pretreat with AV nodal blocking agents to = avoid=20 accelerated ventricular response=20
- Avoid in patients with CHF, left ventricular = dysfunction, or CAD=20
- May exacerbate COPD=20
- Dose for cardioversion=20
  
  Oral: 450=96600 mg=20
  I.V.: 1.5=962.0 mg/kg over 10=9620 = min
- Dose for maintenance of sinus rhythm: = 450=96900 mg=20 q.d.=20
  - Reduced dose with hepatic dysfunction=20
  - Cost/mo: $198
Quinidine=20
- Toxicity: hypotension, nausea, diarrhea, = fever,=20 hepatic dysfunction, thrombocytopenia, hemolytic anemia=20
- Time to cardioversion: 2=966 hr=20
- Safety concerns limit use in cardioversion; = side=20 effects and drug interactions limit use=20
- Associated with TdP=20
- Pretreat with AV nodal blocking agents to = avoid=20 accelerated ventricular response=20
- Avoid in patients with CHF or left = ventricular=20 dysfunction=20
- Dose for cardioversion=20
  
  Oral: 0.75=961.5 g in divided doses over = 6=9612=20 hr=20
  I.V.: 1.5=962.0 mg/kg over 10=9620 = min
- Dose for maintenance of sinus rhythm: = 600=961,500 mg=20 q.d.=20
  
  Cost/mo: $77
Disopyramide
- Toxicity: dry mucous membranes, = constipation, urinary=20 retention; significant reduction in left ventricular function =
- Time to cardioversion: < 12 hr=20
- Efficacy for cardioversion of AF reduced or=20 unproven=20
- Side effects limit use=20
- Associated with TdP=20
- Pretreat with AV nodal blocking agents to = avoid=20 accelerated ventricular response=20
- Avoid in patients with CHF or left = ventricular=20 dysfunction=20
- Dose for cardioversion: 200 mg q. 4 hr, up = to 800=20 mg=20
- Dose for maintenance of sinus rhythm: = 400=96750 mg=20 q.d.=20
  - Reduced dose with renal = insufficiency=20
  - Cost/mo: $84
Procainamide=20
- Toxicity: drug-induced lupus, vasculitides, = blood=20 dyscrasias, CNS disturbances=20
- Time to cardioversion: < 24 hr=20
- Efficacy for cardioversion of AF low or=20 unproven=20
- Side effects limit use=20
- Associated with TdP=20
- Dose for cardioversion: 100 mg I.V. q. 5 = min, up to=20 1,000 mg=20
- Dose for maintenance of sinus rhythm: = 1,000=964,000 mg=20 q.d.=20
  - Reduced dose with renal insufficiency or = hepatic=20 dysfunction=20
  - Cost/mo: $64 =

Drugs for Ventricular Rate Control in Atrial=20 Fibrillation=20

Goals=20
- Resting ventricular rate: 60=9680 = beats/min=20
- Rate during moderate exercise: 90=96115 = beats/min=20
Patient considerations=20
- Reduced ventricular function=20
  - Avoid diltiazem, verapamil=20
  - Beta blockers preferable for acute and = long-term=20 rate control
- CAD=20
  - Beta blockers preferred (reduced = mortality)=20
- High sympathetic tone=20
  - Digoxin effects attenuated; rarely useful = for rate=20 control
- Pulmonary disease=20
  - Diltiazem and verapamil preferred in = patients with=20 asthma=20
  - Monitor beta blockers carefully in = patients with=20 COPD
- Atrial flutter=20
  - Rate control often difficult to achieve; = consider=20 radiofrequency ablation for primary therapy =
Esmolol=20
- I.V. loading dose: 0.5 mg/kg over 1 min =
- I.V. maintenance dose: 5=9620 mg/kg/min =
Metoprolol=20
- I.V. loading dose: 2.5=965 mg over 2 min, up = to 15=20 mg=20
- I.V. maintenance dose: bolus q. 4=966 = hr=20
- Oral maintenance dose: 50=96200 mg q.d. in = divided=20 doses=20
  - Cost/mo: $14
Propranolol=20
- I.V. loading dose: 0.15 mg/kg over 1 min, = repeat=20 once=20
- I.V. maintenance dose: bolus q. 4 hr=20
- Oral maintenance dose: 80=96240 mg q.d. in = divided=20 doses=20
  - Cost/mo: $19.50 =
Diltiazem=20
- I.V. loading dose: 0.25 mg/kg over 2 min=20
- I.V. maintenance dose: 5=9615 mg/hr=20
- Oral maintenance dose: 120=96360 mg q.d. in = divided=20 doses=20
  - Cost/mo: $20
Verapamil=20
- I.V. loading dose: 75=96150 =B5g/kg over 2 = min=20
- I.V. maintenance dose: bolus q. 3=966 hr=20
- Oral maintenance dose: 120=96360 mg q.d. in = divided=20 doses=20
  - Cost/mo: $15
Digoxin=20
- I.V. loading dose: 0.25 mg q. 2 hr up to 1.5 = mg=20
- I.V. maintenance dose: 0.125=960.25 mg q.d.=20
- Oral loading dose: 0.25 mg q. 2 hr up to 1.5 = mg=20
- Oral maintenance dose: 0.125=960.25 mg = q.d.=20
  
  Cost/mo: $9
Amiodarone=20
- I.V. loading dose: 1.2=961.8 g/day until 10 = g=20 total=20
- I.V. maintenance dose: 720 mg/day up to 3 wk =
- Oral loading dose: 800 mg/day =D7 1 wk, 600 = mg/day =D7 1=20 wk, 400 mg/day =D7 4=966 wk=20
- Oral maintenance dose: 200 mg q.d=20
  
  Cost/mo: $29 =

Antithrombotic Therapy in Atrial=20 Fibrillation=20

Considerations=20
- Antithrombotic therapy in atrial flutter = based on AF=20 guidelines=20
- Tight monitoring in patients ≥ 75 yr = because of=20 increased risk of both stroke and bleeding
- Risk of thromboembolism 1%=965% at = cardioversion;=20 consider anticoagulation before, after, or both=20
- Discontinuance of anticoagulation for = elective=20 surgery=20
  - If no mechanical heart valve, discontinue=20 anticoagulation for up to 1 wk before procedure
  - If mechanical heart valve, discontinue = warfarin 1 wk=20 before procedure; continue anticoagulation with intravenous = unfractionated=20 heparin
ACC/AHA/ESC recommendations for antithrombotic = therapy=20 in AF=20
- Age < 60 yr, no heart disease (lone = AF)=20
  - Aspirin, 325 mg q.d., or no therapy =
- Age < 60 yr, heart disease but no risk=20 factors=20
  - Aspirin, 325 mg q.d.
- Age ≥ 60 yr but no risk factors =
  - Aspirin, 325 mg q.d.
- Age ≥ 60 yr with diabetes mellitus or = CAD=20
  - Warfarin (INR, 2.0=963.0)=20
  - Consider addition of aspirin, 81=96162 mg = q.d.=20
- Age ≥ 75 yr, especially in = women=20
  - Warfarin (INR, 2.0)
- Heart failure=20
  - Warfarin (INR, 2.0)
- Left ventricular ejection fraction ≤ = 0.35=20
  - Warfarin (INR, 2.0=963.0) =
- Thyrotoxicosis=20
  - Warfarin (INR, 2.0=963.0) =
- Hypertension=20
  - Warfarin (INR, 2.0=963.0) =
- Rheumatic heart disease (mitral = stenosis)=20
  - Warfarin (INR, 2.5=963.5, possibly = higher)=20
- Prosthetic heart valves=20
  - Warfarin (INR, 2.5=963.5, possibly = higher)=20
- Previous thromboembolism=20
  - Warfarin (INR, 2.5=963.5, possibly = higher)=20
- Persistent atrial thrombus on TEE=20
  - Warfarin (INR, 2.5=963.5, possibly = higher)=20

Nonpharmacologic Therapy

Electrical Cardioversion of Atrial = Fibrillation=20

DC cardioversion
- Most effective method for achieving sinus = rhythm=20 (70%=9690% success)=20
  - Highly effective for cardioversion of = atrial flutter=20 (~ 95% success)
- Success rate enhanced by pretreatment with=20 antiarrhythmic drugs: amiodarone, ibutilide, sotalol, flecainide,=20 propafenone, disopyramide, quinidine=20
- Risks=20
  - Reprogramming or malfunction of permanent = pacemakers=20 or ICDs=20
  - Life-threatening arrhythmias =
- Risk factors for failure=20
  - Longer duration of AF (particularly > 1 = yr)=20
  - Older age=20
  - Left atrial enlargement=20
  - Cardiomegaly=20
  - Rheumatic heart disease=20
  - Transthoracic impedance=20

Nonpharmacologic Approaches to = Maintaining Sinus=20 Rhythm in Atrial Fibrillation=20

Considerations=20
- Offers benefit of reducing use of=20 antiarrhythmics=20
- AV nodal ablation with permanent pacemaker = insertion=20 an option if rate control not achieved by pharmacologic = therapy=20
- Permanent pacemaker an option in patients = with labile=20 response to pharmacologic therapy and symptomatic bradycardia =
Catheter-based radiofrequency ablation of = ectopic=20 arrhythmic foci=20
- Success rate in paroxysmal AF > 70%, = lower in=20 chronic AF=20
- Consider as primary therapy for atrial = flutter=20
- Risks: thromboembolism, pulmonary vein = stenosis,=20 cardiac perforation
Surgical ablation=20
- Success rate in eliminating AF > = 90%=20
- Permanent pacemaker required postoperatively = in 25% of=20 patients=20
- In general, consider only if patient = undergoing=20 cardiac surgery for other indications
Implantable atrial defibrillators=20
- Indications=20
  - Unable to tolerate other strategies of = ventricular=20 rate control=20
  - Condition refractory to pharmacologic and = ablative=20 therapies
- Limitations=20
  - Pain from the electrical shock=20
  - Risks of implantation (e.g., bleeding,=20 infection)

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Best=20 References

Fuster V, et al: J Am Coll Cardiol 38:1231, 2001 = [PMID=20 11583910]

Hirsh J, et al: J Am Coll Cardiol 41:1633, 2003 = [PMID=20 12742309]

Prystowsky EN, et al: Circulation 93:1262, 1996 = [PMID=20 8653857]

The authors have no = commercial=20 relationships with manufacturers of products or providers of services = discussed=20 in this module.

February=20 2006