Atrial Fibrillation Andreas Stein Robert Smith, M.D. August 11, 2003

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.

Prevalence Overall prevalence 1% Increases with age Higher in men than in women

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

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

Etiology (cont) Common diseases underlying AF: Hypertension Coronary Heart disease / MI Rheumatic heart disease Dilated cardiomyopathy Hypertrophic cardiomyopathy Congenital heart disease Hyperthyroidism Inflammation

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

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

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

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

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

Drugs for AF <7 Days

Drugs for AF >7 Days

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

Maintenance of NSR

Rate control in chronic AF Slowing AV nodal conduction: beta blocker calcium channel blocker digoxin

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

Prevention of Systemic Embolization Anticoagulation during restoration of NSR –AF > 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 (<65y; no risk factors) –Warfarin: other than low risk patients ~70% reduction of stroke