Review Question - QID 104081

This patient is presenting with atrial fibrillation with rapid ventricular response given his rapid heart rate and ECG demonstrating an irregular rhythm with no P waves. The most appropriate initial step in management is a rate control agent like metoprolol.

Atrial fibrillation occurs when conduction in the atria fires in a continuous and chaotic pattern resulting in an irregular and rapid ventricular rate without discernible P waves. There are multiple causes including coronary artery disease, myocardial infarction, hypertension, mitral valve disease, pericarditis, pulmonary disease, alcohol intake, hyperthyroidism, and stress. Clinically, patients present with palpitations, dizziness, angina, and an irregular pulse. ECG will demonstrate irregular R-R intervals and tachycardia without P waves. Treatment depends on whether the patient is stable or unstable. In the unstable patient, immediate electrical cardioversion to sinus rhythm is indicated. In a stable patient, treatment focuses on rate control with beta-blockers or calcium channel blockers. After the rate is controlled, patients will often be started on anticoagulation. Stable patients generally are not cardioverted given the minor risk of shocking back into sinus rhythm and subsequently dislodging a clot unless there is a clear onset of symptoms or the patient is anticoagulated.

Figure A depicts the classic irregularly irregular rhythm without P waves indicative of atrial fibrillation.

Incorrect Answers:
Answer 1: Amiodarone is a rhythm control agent and is associated with worse outcomes in elderly patients when compared to rate control agents in the long-term management of atrial fibrillation.

Answer 2: Cardioversion is indicated in an unstable patient (meaning the patient is hypotensive or is not perfusing their end organs) or in a patient who does not respond to initial management with rate control/rhythm control agents.

Answer 3: Digoxin does not have a clear indication in the management of atrial fibrillation. It is an AV nodal blocking agent and could control the rate. It may be appropriate in patients in whom there is concern that a beta/calcium channel blocker may depress cardiac output leading to hypotension. However, if the patient is hypotensive, cardioversion is more appropriate.

Answer 4: Labetalol can used in the management of atrial fibrillation with rapid ventricular response; however, it does not have as good of outcomes as metoprolol or propranolol in terms of long-term management.

Bullet Summary:
Long-term management and rate control of atrial fibrillation involves either beta-blockers (such as metoprolol or propranolol) and calcium channel blockers (such as diltiazem and verapamil).