A 55-year-old woman with a history of mitral valve replacement and mitral stenosis presents with increasing dyspnea on exertion and palpitations. ECG shows atrial flutter with 2:1 AV block. Her INR has been therapeutic for 4 weeks. What is the most appropriate next step in treatment?

A 55-year-old woman with a history of mitral valve replacement and mitral stenosis presents with increasing dyspnea on exertion and palpitations. ECG shows atrial flutter with 2:1 AV block. Her INR has been therapeutic for 4 weeks. What is the most appropriate next step in treatment?

• A. IV ibutilide
• B. IV amiodarone
• C. IV quinidine
• D. IV vasotec

Answer: (A)

Atrial flutter with a 2:1 AV block can be converted to sinus rhythm rapidly with a pharmacologic agent that specifically targets atrial tissue and shortens the time to re-entry termination. Intravenous ibutilide is a class III antiarrhythmic that prolongs atrial refractoriness, making it particularly effective for acute conversion of atrial flutter to sinus rhythm, often within minutes of administration. In this patient, who is symptomatic but hemodynamically stable and has been on therapeutic anticoagulation for a prosthetic mitral valve, rapid chemical cardioversion is appropriate to relieve symptoms and restore normal atrial activity. Ibutilide carries a risk of QT interval prolongation and torsades de pointes, so before administration, correct and monitor electrolytes and obtain continuous telemetry. It is contraindicated in patients with significant QT prolongation or electrolyte disturbances. Other options include amiodarone, which can convert atrial arrhythmias but usually acts more slowly and is not as specific for flutter in the acute setting, and quinidine, which has notable proarrhythmic risk in structural heart disease. Vasotec is an ACE inhibitor and does not address the arrhythmia.

Atrial flutter with a 2:1 AV block can be converted to sinus rhythm rapidly with a pharmacologic agent that specifically targets atrial tissue and shortens the time to re-entry termination. Intravenous ibutilide is a class III antiarrhythmic that prolongs atrial refractoriness, making it particularly effective for acute conversion of atrial flutter to sinus rhythm, often within minutes of administration. In this patient, who is symptomatic but hemodynamically stable and has been on therapeutic anticoagulation for a prosthetic mitral valve, rapid chemical cardioversion is appropriate to relieve symptoms and restore normal atrial activity.

Ibutilide carries a risk of QT interval prolongation and torsades de pointes, so before administration, correct and monitor electrolytes and obtain continuous telemetry. It is contraindicated in patients with significant QT prolongation or electrolyte disturbances.

Other options include amiodarone, which can convert atrial arrhythmias but usually acts more slowly and is not as specific for flutter in the acute setting, and quinidine, which has notable proarrhythmic risk in structural heart disease. Vasotec is an ACE inhibitor and does not address the arrhythmia.