Atrial Fibrillation

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Atrial Fibrillation

• Andreas Stein
• Robert Smith, M.D.
• August 11, 2003

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Definition
Atrial fibrillation/flutter is a disorder of
heart rhythm (arrhythmia) usually with rapid
heart rate, in which the upper heart chambers
(atria) are stimulated to contract in a very
disorganized and abnormal manner.
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Prevalence

• Overall prevalence 1
• Increases with age
• Higher in men than in women

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Classification

• Paroxysmal AF less than 7 days
• Persistent AF longer than 7 days
• Permanent AF longer than 1 year
• Lone AF no structural heart disease

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Etiology

• AF with Heart disease complicated by the
  following is most common (80)
• Atrial enlargement
• Elevation of atrial pressure
• Infiltration or inflammation of atria
• Lone AF (20)
• Electrophysiologic properties

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Etiology (cont)

• Common diseases underlying AF
• Hypertension
• Coronary Heart disease / MI
• Rheumatic heart disease
• Dilated cardiomyopathy
• Hypertrophic cardiomyopathy
• Congenital heart disease
• Hyperthyroidism
• Inflammation

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Evaluation of AF

• History and Physical Examination
• Define symptoms associated with AF
• Clinical type or pattern (Classification)
• Onset or date of discovery
• Frequency and Duration
• Precipitating causes and modes of termination
• Response to drug therapy
• Presence of heart disease or potentially
  reversible causes

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Evaluation of AF (cont)

• Electrocardiogram
• Presence of AF
• Left ventricular hypertrophy
• Preexcitation
• Bundle branch block
• Prior MI
• Measure important intervals such as RR, QRS and
  QT

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Evaluation of AF (cont)

• Echocardiogram
• Transthoracic Echocardiogram
• size and function of atria and ventricles
• low sensitivity for thrombi
• Transesophageal Echocardiogram
• High sensitivity for atrial thrombi
• Need of anticoagulation prior to cardioversion
• Assessment for Hyperthyroidism
• TSH measurement

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General Treatment Issues

• Rhythm control
• reversion to normal sinus rhythm
• Rate control
• administration of medications to control the
  ventricular rate in chronic AF
• Choosing between rhythm and rate control
• Prevention of systemic embolization

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Rhythm Control

• Synchronized External DC Cardioversion
• hemodynamically stable and unstable patients
• 80 overall success rate
• Pharmacologic Cardioversion
• hemodynamically stable patients
• Class IA IC III anti arrhythmic drugs
• 60 overall success rate

Rule out atrial thrombi by TEE or
anticoagulation for 3 4 week
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Drugs for AF lt7 Days
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Drugs for AF gt7 Days
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Maintenance of NSR

• 20 maintain in NSR without chronic
  anti-arrhythmic therapy
• Class IA, IC, and III drugs
• Flecainide ? minimal heart disease
• Amiodarone ? reduced EF
• Sotalol ? coronary heart disease
• Alternative methods
• ablative procedures
• pacing
• insertion of an implantable atrial defibrillator

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Maintenance of NSR
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Rate control in chronic AF

• Slowing AV nodal conduction
• beta blocker
• calcium channel blocker
• digoxin

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Rhythm Control vs. Rate Control

• Embolic events occur with equal frequency in rate
  control and rhythm control strategies
• Almost significant trend toward a lower incidence
  of the primary end point with rate control

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Prevention of Systemic Embolization

• Anticoagulation during restoration of NSR
• AF gt 48 hours 3 to 4 weeks of warfarin prior to
  and after cardioversion
• recommended target INR is 2.5
• Anticoagulation in chronic AF
• Aspirin low risk patients (lt65y no risk
  factors)
• Warfarin other than low risk patients
  70 reduction of stroke

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