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Atrial Fibrillation
Assessment and Management in the ED
Joseph R. Cline MD FACEP
Associate Professor (CHS)
Section of Emergency Medicine
University of Wisconsin School of Medicine and Public Health
Atrial Fibrillation
Objectives
• Review prevalence and associated and
confounding conditions
• Review clinical assessment and
categorization
• Review management strategy
• Discuss classification of antiarrhythmics
and the use in AF
• Discuss thromboembolic risk in AF
Atrial Fibrillation
-- Prevalence --
In a cross-sectional study of almost 1.9 million men and women, the prevalence of atrial fibrillation increases with age,
ranging from 0.1 for those less than 55 years of age to over 9 percent in those 85 years of age.
At all ages, the prevalence is higher in men than women. Data from Go, AS, Hylek, EM, Phillips, K, et al, JAMA 2001; 285:2370.
Atrial Fibrillation
-- Incidence and Prevalence -• Overall prevalence = 0.4% of U.S. population
• From 1996-2001, primary hospital discharge diagnosis of
Atrial fibrillation increased by 34%
• Most common arrhythmia in the ED setting: 1 – 3% of
ED visits overall
• Prevalence: age < 55 yrs < 0.1%
> 55 yrs = 5%
> 80 yrs > 9%
• Life-time risk = 25% for age > 40 yrs (M or F)
• Accounts for 15% of all strokes
• AF increases risk of stroke 5 X
Atrial Fibrillation
-- Classification -• Paroxysmal AF – duration less than 7 days and may be
recurrent
• Persistent AF – fails to self-terminate; duration greater
than 7 days; can be terminated by cardioversion
• Permanent AF – duration more than 1 year;
cardioversion either failed or has not been attempted
• “Lone” AF – paroxysmal, persistent, or permanent AF
without structural heart disease
Atrial Fibrillation
-- Prevalence in associated diseases -• Hypertension – increased relative risk of only 1.42; however
prevalence of hypertension accounts for the high association
• CAD – AF is transient in 6-10% of MI patients; however it is almost
never in isolation to other ECG findings of ACS (Zimetbaum et al. Incidence
and predictors of myocardial infarction among patients with atrial fibrillation. J Am Coll Cardiol
2000; 36;1223)
Incidence in chronic, stable CHD is 0.6%
• Valvular heart disease
– High prevalence with Rheumatic heart disease
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MS + MR – 52%
MS alone – 29%
MR alone - 16%
AS alone – 1%
– Degenerative MR incidence 5% per year
Atrial Fibrillation
-- Prevalence in associated diseases, cont. -• Heart Failure – 10-30%
• Pulmonary embolism – 10-14 % (rarely the only sign or
symptom)
• Hyperthyroidism – low TSH in 5.4%; clinical
hyperthyroidism present in 1%
• COPD
• Post cardiac surgery
• Pericarditis
• Obstructive sleep apnea ( for patients with AF and OSA, incidence of AF
recurrence is 2X for those not treated with CPAP)
• Congenital heart disease
• Peripartum cardiomyopathy
• “Holiday Heart”
Atrial Fibrillation
-- Pathogenesis -• Underlying heart disease of any cause that is
complicated by:
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–
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–
heart failure
atrial enlargement
elevated atrial pressure
inflammation or infiltration of the atria
• Echocardiographic risk factors
– increased left ventricular wall thickness
– left atrial diameter > 4 cm
– reduced left ventricular fractional shortening
• Triggering event
– majority related to atrial premature beat
– minority related to atrial flutter or atrial tachycardia
Atrial Fibrillation
-- History and Physical Exam --
• Define symptoms
• Define pattern
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Paroxysmal
Persistent
Recurrent
Permanent
• Onset or date of discovery
• Frequency and duration of episodes
• Precipitating causes and modes of termination
Atrial Fibrillation
-- History --
• Symptoms
– Palpitations, weakness, dizziness, reduced exercise
capacity, dyspnea
– Angina, CHF symptoms, syncope (hypotension)
relate to underlying heart disease
– Up to 90% of episodes are asymptomatic with
approximately 20% of such episodes longer than 48
hrs
– 90% of AF patients have recurrent episodes
Atrial Fibrillation
-- Exam --
• ABC’s
• Vital signs
– Rate / BP to assess perfusion and guide decision for
urgent / emergent ECV
• Assess for signs of CHF
• Heart tones: variable intensity of S1 is
diagnostic of atrial fibrillation
Atrial Fibrillation
-- ECG --
• Verification of diagnosis
– irregularly irregular
– No discernable P waves
• Identify associated findings or complications
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–
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MI
LVH
Bundle branch block
Pre-excitation
Atrial Fibrillation
-- ECG -Aeschmann beats – aberrently conducted beats
following a shorter R-R interval than the previous
R-R interval
Atrial Fibrillation
-- Chest X-ray --
• Identify heart size, vasculature
• Assess for additional complicating diseases
– COPD
– Pneumonia
Atrial Fibrillation
-- Lab --
• Standard electrolytes – assess for hypokalemia
• TSH and free T4
– For all cases of new onset Atrial fibrillation
– Patients with low TSH and normal free T4 have
subclinical hyperthyroidism
• INR
– Most patients with AF will need anticoagulation
– Patients currently anticoagulated need confirmation of
theraputic level
Atrial Fibrillation
-- Management and Disposition -• Which category?
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Recent onset AF
Recurrent paroxysmal AF
Recurrent persistent AF
Permanent (Chronic) AF
and patient condition, determines
• Which primary option
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Rate control
Urgent cardioversion
Delayed cardioversion
Rhythm control / maintenance if converted
Systemic embolization prevention
Atrial Fibrillation
-- Management and Disposition --
“Elective” cardioversion in the ED
– duration clearly identified less than 48 hrs
– No reversible cause
– low risk of intra-cardiac thrombus formation
Atrial Fibrillation
-- ED Cardioversion in the stable patient -Burton, John H. et al. Electrical cardioversion of ED patients with Atrial
Fibrillation. Annals of Emergency Medicine 2004;44: 22-30
Retrospective,
consecutive cohort
42 months,
Oct 1998 – March 2002
4 institutions
3,688 AF encounters
Excluded: Cardioversion for unstable patients
hypotension, dyspnea, ischemic chest pain, altered
consciousness, CHF, acute MI
No standardized protocol at any of the study sites
91% discharged
332 successful (86%)
9% admitted
388 stable AF encounters
(10.5%)
Mean age = 61 +/- 13 yrs
55% discharged
56 unsuccessful (14%)
45% admitted
Atrial Fibrillation
-- Management and Disposition --
“Urgent” or “Emergent” cardioversion in the ED
What are the indications?
What are the contraindications?
Atrial Fibrillation
-- Management and Disposition -Urgent cardioversion
Restoration of sinus rhythm takes precedence over mitigation of thromboembolic risk
Indicated if any of the following is present:
• Active ischemia
• Significant hypotension where LV dysfunction (systolic or diastolic) or valvular
disease is a factor
• Severe CHF
• Pre-excitation syndrome (eg WPW)
“Relative” Contraindications to urgent cardioversion
– Duration of episode > 48hrs or uncertain duration
– Associated mitral valve disease, cardiomyopathy or CHF (known EF < 50%)
– Prior history of thromboembolic event
Atrial Fibrillation
-- Management and Disposition --
Rate control
• indicated if starting Class 1a or 1c antiarrhythmic drug due to
possible recurrence with Atrial flutter with 1:1 conduction
• Necessary for prevention of tachycaria-induced left venticular
dysfunction
Agents for rate control
– Beta blockers
• IV therapy: Metoprolol, Esmolol
• Oral therapy: Atenolol
– Calcium channel blockers
• Diltiazem
• Verapamil
– Digoxin
• Useful only in CHF patients or as second/third line agent
Atrial Fibrillation
-- Antiarrhythmic agents --
Myocardial Cellular Electrophysiology
Fast Channel (Na+)
Action Potential
Slow Channel (Ca++)
Action Potential
Purkinje fibers
Sinus / A-V Nodes
1
0
2
2
3
0
4
Class 1 antiarrhythmics
Class 4 antiarrhythmics
-Slowing of conductance
-Slowing of AV nodal conductance
+
-Phase 0 is determined by Na channel -Phase 0 is determined by Ca++ channel
-Slowing of conduction velocity
-Slowing of conduction velocity in
and decreased excitability
sinus and AV nodes
-- Antiarrythmic Agent Classification—
Vaughn-Williams Classification
(Journal of Clinical Pharmacology, 1984)
Class 1- depression of Na+conductance during phase 0; slowed conduction
velocity and decreased excitability
– 1a:
moderate depression of Na+ conductance in resting and depolarized tissue;
depression of K+ currents and prolongation of repolarization
• Quinidine, Procainamide, Disopyramide
– 1b: depression of Na+ conductance in depolarized fibers only;
• Lidocaine, Tocainide, Phenytoin
– 1c:
marked depression in Na+ conduction; no effect on repolarization
• Encainide, Flecainide, Propafenone
Class 2- β-adrenergic receptor blockers
• Atenolol, Metoprolol
Class 3- prolongation of action potential duration by varied effects
• Bretylium, Sotolol, Amiodarone, Ibutilide, Dofetilide
depression of Ca+-dependent slow channels
Class 4-
• Diltiazem, Verapamil
Atrial Fibrillation
-- Management and Disposition --
Delayed cardioversion
– AF duration of 48 hours or duration unknown
– Associated mitral valve disease, cardiomyopathy or
CHF
– Prior history of thromboembolic event
– Anticoagulate with a goal INR of 2.0 to 3.0 for at least
three weeks before and four weeks after either
electrical or pharmacologic cardioversion.
Atrial Fibrillation
-- Management and Disposition for Delayed ECV -•
Strategy 1 (Conventional)
–
Oral anticoagulation with Warfarin
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No antiarrythmics
Rate control as needed – hospitalization usually necessary if rate control needed
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Target INR 2.0 – 3.0
Metoprolol
Diltiazem
Digoxin (useful only in presence of CHF)
Scheduled ECV after minimum of 3 weeks of anticoagulation
4 weeks of anticoagulation after ECV
Strategy 2
– Indication
–
• recent onset but > 48 hrs
• useful for hospitalized patients (rate control, associated complications) and stable
patients for which earlier timing is useful
• Patients with increased risk of hemorrhage with anticoagulation
Screening Transesophageal echocardiography (TEE)
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No anticoagulation
No antiarrhythmics
Rate control as needed
ECV if no thrombi seen
Atrial Fibrillation
-- Indications for hospitalization --
• For the treatment of an associated medical
problem, which is often the reason for the
arrhythmia
• For elderly patients who are more safely treated
for AF in hospital
• For patients with underlying heart disease who
have hemodynamic consequences from the AF
or who are at risk for a complication resulting
from therapy of the arrhythmia
Atrial Fibrillation
-- Rate control alone vs rhythm control-Rhythm control strategy
– Advantages:
• Better exertional capacity
• Improved cardiac function for CHF patients
• Mitigation of other arrhythmic related symptoms (eg palpitations)
– Disadvantages:
• frequent recurrences of AF – 50% of patient recurr in 3-6 months
• repeated need for electrical cardioversion;
• adverse effects of prophylactic antiarrhythmic drugs including life-threatening
events related to proarrhythmic effects
• No clear benefit of either approach for patients over 65 years of age;
trend for increased mortality in rhythm control (AFFIRM trial, NEJM 2002,
> 4,000 patients)
• Rate control with anticoagulation is acceptable in patients 65 yrs or
greater
• Strategy is weighed for acutely symptomatic patient with new onset
of Atrial fibrillation, particularly if < 65 yrs
Atrial Fibrillation
-- Rate control alone vs rhythm control -VanGelder, et al, A Comparison of Rate Control and Rhythm Control in
Patients with Recurrent Persistent Atrial Fibrillation, NEJM
2002;347:1834-40
522 Patients with persistent AF after
previous electrical cardioversion
Mean age
68 +/- 8
Mean duration of AF diagnosis
315 d
Follow up period of at least 2 yrs
Primary Endpoints:
Death
CHF
TE event
Bleeding
Pacer
severe drug adverse
event
Mean duration of presenting episode 32 d
No history of heart disease
Rhythm control
Entry: ECV + Sotolol
1st recurrence: ECV +
Flecanide or Propafenone
2nd recurrence: Amiodarone load +
ECV + Amiodarone main.
21%
Rate control
Target HR < 100
Digoxin, Diltiazem,
β blocker – alone or
In combination
Primary endpoint:
Rhythm control = 23%
Rate control = 17%
All patients anticoagulated: could be discontinued if
In NSR 4 weeks after ECV
Atrial Fibrillation
-- Rate control alone vs rhythm control -VanGelder, et al, A Comparison of Rate Control and Rhythm
Control in Patients with Recurrent Persistent Atrial
Fibrillation, NEJM 2002;347:1834-40
Factors related to lack of risk reduction with rhythm control strategy
•Tachycardia induced cardiomyopathy and heart failure also are
likely reduced with rate control (incidence of CHF similar in
the two arms of the study)
•Patients with risk factors for stroke are still at risk for stroke even
when sinus rhythm is maintained (17% of the thromboembolic
events occurred after cessation of anticoagulant therapy and in
5 of 6 cases the patient was in sinus rhythm at the time of the event)
•Senescent conduction disease is occasionally unmasked by rhythm
control strategy
Atrial Fibrillation
-- Maintenance of Sinus Rhythm after Chemical or Electrical Cardioversion -Canadian Trial of Atrial Fibrillation Investigators
Roy, et al Amiodarone to Prevent Recurrence of Atrial Fibrillation, NEJM,
2000;342:913-920
403 patients; 19 centers
201 Amiodarone
202 Propafenone ; Sotolol
101 Propafenone
101 Sotolol
Mean 16 month follow-up
35% recurrence for Amiodarone
63% recurrence for Propafenone or Sotolol
Atrial Fibrillation
-General Management Principles-- Pharmacologic Cardioversion -• Semi – urgent (hospitalization or Obs Unit)
– Class 1c
• used only if no pre-existant heart disease
• monitoring for rapid conducting At. Flutter
– Flecainide
– Propafenone
– Class 3
• monitoring for QT prolongation; Torsade
– Dofetilide
– Ibutilide
• Out-patient / Ambulatory scenario
– Class 1c “Pill-in-the-Pocket”
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•
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Flecainide
Propafenone
Used only when demonstrated effective under as in-patient
Must have AV nodal blockade with β blockade or Ca++ channel blocker to
prevent 1:1 AV conduction if Atrial flutter occurs
– Class 1c Extended dosing
• Amiodarone –particularly with patients with pre-existing heart disease
Atrial Fibrillation
-General Management Principles-- Maintenance of Sinus Rhythm after Chemical or Electrical Cardioversion –
ACC / AHA / ESC anticoagulation recommendations
Atrial Fibrillation
-General Management Principles-
Assessment of Thromboembolic Risk
Atrial Fibrillation
-- Risk for Thromboembolism -Go, AS, Hylek, EM, Chang, Y, et al, JAMA 2003
Risk assessment – CHADS2
• CHF – any history
(1)
• Hypertension – prior history
(1)
• Age > 75
(1)
• Diabetes mellitus
(1)
• Stroke, TIA or systemic embolic event (2)
Atrial Fibrillation
-- Risk for Thromboembolism --
Risk assessment – CHADS2
Go, AS, Hylek, EM, Chang, Y, et al, JAMA 2003
Score (risk)
Event rate (% / yr)
Warfarin
0 (low)
1 (interm)
2 (interm)
3 (high)
4 (high)
5,6 (high)
0.25
0.72
1.27
2.2
2.35
4.6
Without Warfarin
0.49
1.52
2.50
5.27
6.02
6.88
NNT
417
125
81
33
27
Atrial Fibrillation
-- Prevention of Thromboembolism -ACC / AHA / ESC anticoagulation recommendations
Age < 60 + heart disease but no other risks:
Age 60 – 75 with no risks:
Age 65 – 75 with heart disease or DM:
Women > 75:
Men > 75:
Age > 65 with CHF:
EF < 35% + Hypertension
Aspirin
Aspirin
Warfarin
Warfarin
Warfarin or Aspirin
Warfarin
Warfarin
Atrial Fibrillation
-- Summary –
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Patients with new onset atrial fibrillation of less than 48 hrs duration, who
have normal ventricular function, no known mitral valvular disease and no
history of thromboembolic event can be considered for cardioversion in
the ED
Up to 90% of atrial fibrillation episodes are asymptomatic with
approximately 20% of such episodes longer than 48 hrs (Select your
cardioversion cases carefully!)
If the episode is greater than 48hrs, rate control, anticoagulate and refer
for delayed cardioversion
TSH and free T4 are essential in the evaluation of initial onset
AF is transient in 6-10% of MI patients; however it is almost never in
isolation to other ECG findings of ACS
CHAD2 scheme is extremely helpful in assessing thromboembolic risk
and need for anticoagulation
In patients greater than age 65, rhythm control strategy is very
appropriate
AF is transient in 6-10% of MI patients; however it is almost never in
isolation to other ECG findings of ACS