Atrial Fibrillation 2016

Management of AF

1. Approach to Atrial
Fibrillation:
LNR González
KH
05/05/2016

2. Atrial fibrillation (AF) is a rapid,
irregularly irregular atrial rhythm.
Symptoms include palpitations and
sometimes weakness, effort intolerance,
dyspnea, and presyncope.
Atrial thrombi often form, causing a
significant risk of embolic stroke.

3. Atrial fibrillation is the most common sustained
arrhythmia
6% over the age of 65 experience it
Responsible for 15% strokes.

4. Etiology
The most common causes  of atrial
fibrillation are hypertension, ischemic or
nonischemic cardiomyopathy, mitral or tricuspid
valvular disorders, hyperthyroidism, and binge
alcohol drinking (holiday heart).
Less common causes  include pulmonary
embolism, atrial septal and other congenital
heart defects, COPD, myocarditis, and
pericarditis. AF without an identifiable cause in
patients < 60 yr is called lone AF.

5. Classification
Acute atrial fibrillation is new-onset AF lasting  <  48 h.
Paroxysmal atrial fibrillation is recurrent AF that typically
lasts  <  48 h and that converts spontaneously to normal sinus rhythm.
Persistent atrial fibrillation lasts  >  1 wk or requires treatment
to convert to normal sinus rhythm.
Long-standing persistent atrial fibrillation lasts > 1 yr, but
there is still the possibility of restoring sinus rhythm.

6. Classification
Permanent atrial fibrillation cannot be converted to
sinus rhythm. The longer AF is present, the less likely is
spontaneous conversion and the more difficult is
cardioversion because of atrial remodeling (rapid atrial
rate-induced changes in atrial electrophysiology that are
dominated by a decrease in atrial refractoriness and may
also include increase in spatial dispersion of atrial
refractoriness slowed atrial conduction velocity, or both).

7. Diagnosis
Diagnosis of atrial fibrillation is by ECG.
Findings include absence of P waves, f
(fibrillatory) waves between QRS
complexes (irregular in timing, irregular in
morphology; baseline undulations at
rates >300/min not always apparent in all
leads), and irregularly irregular R-R
intervals

8. Diagnosis
Echocardiography
Thyroid function tests

10. Treatment
Rate control with drugs or AV node
radiofrequency ablation
Sometimes rhythm control with
cardioversion, drugs, or AF substrate
ablation
Prevention of thromboembolism

11. Ventricular rate control
Patients with AF of any duration require
rate control (typically to < 100 beats/min at
rest) to control symptoms and prevent
tachycardia-induced cardiomyopathy.
For acute paroxysms of rapid rate (eg, 140
to 160 beats/min), IV AV node blockers are
used

12. Ventricular rate control
 AV node blockers should not be used in
patients with Wolff-Parkinson-White
syndrome when an accessory AV
pathway is involved (indicated by wide
QRS duration); these drugs increase
frequency of conduction via the bypass
tract, possibly causing ventricular
fibrillation. 

13. Ventricular rate control
Beta-blockers (eg, metoprolol, esmolol)
are preferred if excess catecholamines
are suspected (eg, in thyroid disorders,
exercise-triggered cases).
Nondihydropyridine calcium channel
blockers (eg, verapamil, diltiazem) are
also effective. 

14. Ventricular rate control
Digoxin is the least effective but may be
preferred if heart failure is present. These
drugs may be used orally for long-term
rate control. When beta-blockers,
nondihydropyridine calcium channel
blockers, and digoxin—separately or in
combination—are
ineffective, amiodarone may be
required.

15. Rhythm control
In patients with heart failure or other
hemodynamic compromise directly
attributable to new-onset AF, restoration
of normal sinus rhythm is indicated to
improve cardiac output. In other cases,
conversion of AF to normal sinus rhythm
is optimal, but the antiarrhythmic
drugs that are capable of doing so (class
Ia, Ic, III) have a risk of adverse effects
and may increase mortality.

16. Rhythm control
For acute conversion, synchronized
cardioversion or drugs can be used.
Before conversion is attempted, the
ventricular rate should be controlled
to < 120 beats/min, and, many patients
should be anticoagulated if AF has been
present > 48 h, patients should typically
be given an oral anticoagulant
(conversion, regardless of method used,
increases risk of thromboembolism).  

17. Rhythm control
Anticoagulation should be maintained
for > 3 wk before conversion when
possible and for at least 4 wk after
cardioversion.

18. Synchronized
cardioversion
100 joules, followed by 200 and 360 joules as needed)
converts AF to normal sinus rhythm in 75 to 90% of
patients.
Cardioversion is more effective in patients with shorter
duration of AF, lone AF, or AF with a reversible cause
 It is less effective when the left atrium is enlarged (> 5
cm), atrial appendage flow is low, or a significant
underlying structural heart disorder is present.

19. Drugs for conversion of
atrial fibrillation to sinus
rhythm
Include class Ia
(procainamide,quinidine, disopyramide), Ic
(flecainide, propafenone), and III
(amiodarone, dofetilide,dronedarone, ibu
tilide, sotalol) antiarrhythmics .
All are effective in about 50 to 60% of
patients, but adverse effects differ. These
drugs should not be used until rate has
been controlled by a beta-blocker or
nondihydropyridine calcium channel
blocker. These converting drugs are also
used for long-term maintenance of sinus
rhythm (with or without previous
cardioversion). Choice depends on patient
tolerance. However, for paroxysmal AF that
occurs only or almost only at rest or during
sleep when vagal tone is high, drugs with
vagolytic effects (eg, disopyramide) may
be particularly effective. Exercise-induced
AF may be better prevented with a beta-
blocker.

20. Drugs for conversion of
atrial fibrillation to sinus
rhythm
These drugs should not be used until rate
has been controlled by a beta-blocker or
nondihydropyridine calcium channel
blocker.
These converting drugs are also used for
long-term maintenance of sinus rhythm.
Exercise-induced AF may be better
prevented with a beta-blocker.

21. Prevention of thromboembolism
during ryhtm control
Patients, particularly those in whom the current
episode of AF has been present > 48 h, have a
high risk of thromboembolism for several weeks
after pharmacologic or direct current
cardioversion.
If the onset of the current episode of AF is not
clearly within 48 h, the patient should be
anticoagulated for 3 wk before and at least 4 wk
after cardioversion regardless of the patient's
predicted risk of a thromboembolic event (class
I recommendation).

22. Prevention of thromboembolism
during rhythm control
Alternatively, therapeutic anticoagulation
is started, transesophageal
echocardiography (TEE) is done, and, if
no left atrial or left atrial appendage clot is
seen, cardioversion may be done,
followed by at least 4 wk of
anticoagulation therapy (class IIa
recommendation).

23. Prevention of thromboembolism
during rhythm control
If urgent cardioversion is required
because of hemodynamic compromise,
cardioversion is done and anticoagulation
is started as soon as is practical and
continued for at least 4 wk.

24. Prevention of thromboembolism
during rhythm control
If the onset of the current episode of AF is
clearly within 48 h, cardioversion may be done
without prior anticoagulation if the patient has
nonvalvular AF and is not at high risk of a
thromboembolic event.
 After cardioversion, therapeutic anticoagulation
is given for 4 wk (class I recommendation);
although this may not be necessary in patients
at low risk of a thromboembolic event (class IIb
recommendation).

25. Long-term prevention of
thromboembolism
Long-term oral anticoagulant therapy is
recommended for patients with rheumatic mitral
stenosis, artificial heart valve, and for
nonvalvular atrial fibrillation patients with a
CHA2DS2-VASc score of 2 (level I
≥
recommendation)
No antithrombotic therapy is recommended for
patients with nonvalvular atrial fibrillation and a
CHA2DS2-VASc score of 0 (level IIa
recommendation)

26. Long-term prevention of
thromboembolism
No antithrombotic therapy, aspirin therapy, or
oral anticoagulant therapy is recommended for
patients with nonvalvular atrial fibrillation and a
CHA2DS2-VASc score of 1 (level IIb
recommendation).
Patients with AF and a mechanical heart
valve(s) are treated with warfarin.
Patients with AF and significant mitral stenosis
are treated with warfarin.

27. Long-term prevention of
thromboembolism
For patients with nonvalvular AF who are
to be treated with an oral anticoagulant, a
class I indication is given
for warfarin with a target INR of 2.0-3.0
(level of evidence A), apixaban (level of
evidence B), dabigatran (level of evidence
B), and rivaroxaban (level of evidence
B).

28. The left atrial appendage may be
surgically ligated or closed with a
transcatheter device when appropriate
antithrombotic therapy is absolutely
contraindicated

30. Ablation procedures for
atrial fibrillation
For patients who do not respond to or cannot
take rate-controlling drugs, radiofrequency
ablation of the AV node may be done to cause
complete heart block; insertion of a permanent
pacemaker is then necessary.
Ablation of only one AV nodal pathway (AV
node modification) reduces the number of atrial
impulses reaching the ventricles and eliminates
the need for a pacemaker, but this approach is
considered less effective than complete ablation
and is rarely used.

31. Ablation procedures for
atrial fibrillation
Ablation procedures that isolate the pulmonary
veins from the left atrium can prevent AF
without causing AV block. In comparison to
other ablation procedures, pulmonary vein
isolation has a lower success rate (60 to 80%)
and a higher complication rate (1 to 5%).
Accordingly, this procedure is often reserved for
the best candidates—younger patients with
drug-resistant AF who have no significant
structural heart disease.

32. Key Points
Atrial fibrillation is an irregularly irregular atrial
rhythm that may be episodic or continuous;
paroxysms of tachycardia may occur.
QRS complexes should be narrow; a wide
complex occurs with intraventricular conduction
defects or Wolff-Parkinson-White syndrome.
Patients should have echocardiography and
thyroid function testing.

33. Key points
Heart rate is controlled (typically to < 100
beats/min at rest); first-line drugs include beta-
blockers and nondihydropyridine calcium
channel blockers (eg, verapamil, diltiazem).
Restoration of sinus rhythm is not as important
as rate control and does not eliminate the need
for anticoagulation but may help patients with
continuing symptoms or hemodynamic
compromise (eg, heart failure); synchronized
cardioversion or drugs can be used.

34. Key points
Anticoagulation is usually necessary
before cardioversion.
Long-term oral anticoagulation to prevent
stroke is required for patients with risk
factors for thromboembolism; aspirin is
used for those with no risk factors.

35. Lenient versus Strict Rate Control in Patients with Atrial
Fibrillation
N Engl J Med 2010; 362:1363-1373April 15, 2010DOI:
10.1056/NEJMoa1001337
Rhythm Control versus Rate Control for Atrial Fibrillation
and Heart Failure
N Engl J Med 2008; 358:2667-2677June 19, 2008DOI:
10.1056/NEJMoa0708789