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Atrial Fibrillation

Atrial fibrillation has a prevalence of 4 percent in the adult population. The prevalence of this arrhythmia increases with age, from less than 0.05 percent in patients 25 to 35 years of age to more than 5 percent in patients over 69 years of age. Atrial fibrillation is associated with an increased susceptibility to embolic stroke. The annual risk of stroke in patients with atrial fibrillation is 4.5 percent. Atrial fibrillation also can decrease exercise tolerance and has been associated with tachycardia-induced cardiomyopathy. Although many patients with atrial fibrillation are

Clinical evaluation

Atrial fibrillation (AF) may manifest only as fatigue caused by impaired cardiac output or the patient may have no symptoms. Palpitations, shortness of breath or chest pain may occur, and syncope may infrequently accompany AF. Symptoms of myocardial ischemia and angina may be caused by the rapid ventricular rate. Paroxysmal AF may cause symptoms that abate and atrial fibrillation, atreal, fibrilation, palpitation, palpatation

The cause of the atrial fibrillation should be identified. Precipitating causes, such as hyperthyroidism, electrolyte abnormalities, and drug toxicity, should be excluded. Stimulant abuse, excess tobacco, alcohol, caffeine, chocolate, over-the-counter cold remedies, and street drugs should be

Physical examination

The pulse is characterized by an irregular-irregular timing and amplitude. The rapid ventricular rate may

Diagnostic evaluation

12-lead electrocardiogram reveals irregular R-R intervals with no P waves. The ventricular rate is

Treatment of acute atrial fibrillation: rate and rhythm control

Patients who are unstable (ie, a heart rate of 150 or more with low blood pressure, angina pectoris, shortness of breath, decreased level of consciousness, shock, pulmonary congestion, congestive heart failure or acute myocardial infarction) during atrial fibrillation require immediate cardioversion using a

Prevention of embolic events during cardioversion

Both electric and pharmacologic cardioversion carry a risk of embolic events, including stroke. Patients with persistent atrial fibrillation of unknown duration or more than 48 hours duration should be treated

Pharmacologic methods of ventricular rate control

The first goals of therapy should be control of the ventricular rate. Intravenous calcium channel blockers and beta blockers have the advantage of rapid onset of action. Digoxin has a delayed onset of action of

Pharmacologic Methods of Acute Cardioversion

Pharmacologic agents may be used for acute cardioversion in patients with atrial fibrillation. All methods of pharmacologic cardioversion are associated with proarrhythmic risks.

Type IA medications

Intravenous procainamide ( Procainamide injection) is effective for cardioversion in up to 60%. In one

Quinidine ( Quinaglute). The conversion rate with oral quinidine is up to 60%. Torsades de pointes is a The conversion rate with oral quinidine is up to 60%. Torsades de pointes is a

Class IC Medications

Flecainide ( Tambocor). A single high-bolus dose of oral flecainide (less than 400 mg within three A single high-bolus dose of oral flecainide (less than 400 mg within three

Propafenone ( ( Rythmol). High-dose (600 mg) oral propafenone has a conversion rate of up to 76%. . High-dose (600 mg) oral propafenone has a conversion rate of up to 76%.

Class III medications

Amiodarone ( Cordarone) does not appear to be effective in converting recent-onset atrial fibrillation to sinus rhythm. Oral amiodarone may be effective as an adjunct to DC cardioversion. does not appear to be effective in converting recent-onset atrial fibrillation to sinus rhythm. Oral amiodarone may be effective as an adjunct to DC cardioversion.

Sotalol ( Betapace) is not useful for the acute termination of atrial fibrillation. Sotalol and amiodarone slow conduction and prolong refractoriness in the atrioventricular node and thus can control ventricular response to atrial fibrillation. is not useful for the acute termination of atrial fibrillation. Sotalol and amiodarone slow conduction and prolong refractoriness in the atrioventricular node and thus can control ventricular response to atrial fibrillation.

Ibutilide ( Corvert) is an intravenous class III antiarrhythmic agent. It is indicated for the acute termination of atrial fibrillation and flutter. The half-life of ibutilide is three to six hours. Its clinical effect is gone in two to six hours. Ibutilide is administered in a dosage of 0.01 mg per kg intravenously over 10 minutes. Conversion rates are between 33-45%. If the first dose is ineffective, a second may be administered before alternative strategies are considered. is an intravenous class III antiarrhythmic agent. It is indicated for the acute termination of atrial fibrillation and flutter. The half-life of ibutilide is three to six hours. Its clinical effect is gone in two to six hours. Ibutilide is administered in a dosage of 0.01 mg per kg intravenously over 10 minutes. Conversion rates are between 33-45%. If the first dose is ineffective, a second may be administered before alternative strategies are considered.

In summary, class IA and class IC agents are effective for acute termination of atrial fibrillation, with conversion rates of 60-80%. Although class III agents are useful as adjuncts to electric cardioversion and are effective in maintaining sinus rhythm, only ibutilide is useful for acute cardioversion.