cardiovascular disorders
Atrial Fibrillation
Key Points
Atrial fibrillation is an irregularly irregular atrial rhythm that may be episodic or continuous; paroxysms of tachycardia may occur. QRS complexes are typically narrow; a wide complex may occur with intraventricular conduction defects or Wolff-Parkinson-White syndrome. Patients should have electrocardiography, echocardiography, and thyroid function testing. Heart rate is controlled typically to<100 beats/minute at rest; first-line medications 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 medication can be used. Anticoagulation is usually necessary before cardioversion. Long-term oral anticoagulation to prevent stroke is required for patients with risk factors for thromboembolism. 