A 70-year-old man comes to the hospital due to fever, lethargy, productive cough, and shortness of breath. He has type 2 diabetes mellitus, hypertension, paroxysmal atrial fibrillation, and peripheral vascular disease. His medications include warfarin, sotalol, insulin detemir, and lisinopril. Chest x-ray shows infiltrates in the left lung base. He is admitted and treated with azithromycin, ceftriaxone, and oxygen therapy. On examination, the patient is now awake and alert but oriented only to person. His blood pressure is 120/70 mm Hg, pulse is 65/min, and respirations are 14/min. Laboratory tests ordered 30 minutes before the first event are shown below. Which of the following is the most appropriate next step in management of this patient?

Question

A 70-year-old man comes to the hospital due to fever, lethargy, productive cough, and shortness of breath.  He has type 2 diabetes mellitus, hypertension, paroxysmal atrial fibrillation, and peripheral vascular disease.  His medications include warfarin, sotalol, insulin detemir, and lisinopril.  Chest x-ray shows infiltrates in the left lung base.  He is admitted and treated with azithromycin, ceftriaxone, and oxygen therapy. On examination, the patient is now awake and alert but oriented only to person.  His blood pressure is 120/70 mm Hg, pulse is 65/min, and respirations are 14/min.  Laboratory tests ordered 30 minutes before the first event are shown below.  Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

Explanation: Torsade de pointes (TdP) is usually a brief arrhythmia that terminates spontaneously. However, patients can have recurrent episodes in rapid succession, with a risk of degenerating into ventricular fibrillation and death. Intravenous magnesium sulfate is considered the first-line therapy in conscious and hemodynamically stable patients with TdP. It is useful for acute treatment and also for the prevention of recurrent TdP episodes in patients with acquired long QT syndrome (LQTS). Treatment with intravenous magnesium sulfate is effective even in patients with normal serum magnesium levels, and it should not be withheld or delayed in patients with normal baseline serum magnesium levels. (Choice A) Amiodarone is a class III antiarrhythmic agent that can markedly prolong the QT interval. It has no role in the acute therapy or prevention of TdP. (Choice B) Class IB antiarrhythmic drugs (eg, lidocaine, phenytoin) shorten the action potential duration and have been effective in the acute management of TdP in some cases. However, these drugs are less effective and predictable and should not be used as initial acute therapy for TdP. (Choice D) Metoprolol has beta-blocking properties that can cause further bradycardia and increase TdP recurrence. It has no role in the acute termination or prevention of TdP. (Choice E) Temporary transvenous pacing is indicated in patients with long QT-related TdP who do not respond to initial intravenous magnesium sulfate. It is especially useful in the management of patients with LQTS associated with bradycardia or sinus pauses (pause-dependent LQTS). Educational objective: Intravenous magnesium sulfate is indicated as first-line therapy for the treatment and prevention of recurrent episodes of torsade de pointes, regardless of the patient's baseline serum magnesium levels. Temporary transvenous pacing should be used in patients who do not respond to intravenous magnesium sulfate. References: Preventing torsades de pointes by careful cardiac monitoring in hospital settings. (http://www.ncbi.nlm.nih.gov/pubmed/18019519) Drug-induced torsade de pointes. Incidence, management and prevention. (http://www.ncbi.nlm.nih.gov/pubmed/7727055)

A 70-Year-Old Man Comes to the Hospital Due to Fever