Atrial Fibrillation Guideline
Atrial fibrillation (AF) is common, has multiple etiologies and multiple potential therapies. It may occur in up to 30% of patients in the ICU and is second in frequency only to ventricular tachycardia among arrhythmias in the ICU. AF increases risk of length of stay in ICU, mortality and risk of MI. Surgery, particularly cardiac surgery, PE, electrical injury, metabolic disturbance, alcohol consumption, HTN, obesity and cardiac disease (particularly valvular disease) have been associated with the development of AF. Adrenergic stimulation associated with SIRS is a major contributor in the ICU and its cause is usually multifactorial. On the contrary, statins reduce the likelihood of AF in some patients.
Importantly, 45% of patients with paroxysmal AF have no preceding cardiac disease. AF may be paroxysmal (terminates spontaneously), recurrent (2 or more episodes), persistent (beyond 7 days) or permanent (more than one year).
A major concern in AF is diminished cardiac output and low BP. Tachycardia in AF contributes to low CO by decreasing ventricular filling and myocardial perfusion, both of which occur in diastole, by diminishing the atrial systole that augments ventricular filling and by increasing myocardial oxygen consumption. Ventricular rate control is the first priority in AF treatment. Second, normal sinus rhythm should be established. Third, thromboembolism should be prevented.
Patients with new-onset AF who are in extremis (shock, chest pain, severe acute pulmonary dysfunction) should be electrically cardioverted. If shock and significant chest pain are absent, AF may be controlled pharmacologically. Drugs for rate control include beta blockers, calcium channel blockers and digoxin. Beta blockers (eg, metoprolol or esmolol) are the preferred agents in most patients but should be avoided in severe pulmonary edema, poor ventricular function and Wolf-Parkinson-White Syndrome. Calcium channel blockers (diltiazem) are an alternative but less optimal choice. Digoxin can control rate but will increase myocardial work, making it a less than optimal alternative. Amiodarone slows rapid rate AF. Electrolytes should be normalized in a patient with any dysrhythmias.
Cardioversion, the second priority, is most successful with synchronized electrical cardioversion. Earlier cardioversion is more likely to effect durable conversion. Among pharmacologic agents for cardioversion, amiodarone is the best choice. It is dosed with an IV bolus followed by infusion and then conversion to oral form. It may cause hypotension but this is not a common side effect. 8-24 hours may elapse before cardioversion occurs with amiodarone. Procainamide is an alternative for chemical cardioversion but should be used with the input of cardiology. Procainamide is a negative inotrope with numerous side effects.
Anticoagulation is indicated for most patients with sustained AF (who cannot be cardioverted) or after successful cardioversion.
Created 3/1/13 (A Bernard: reviewed 9/26/24 (A Bernard)
