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 the second day of hospitalization, he has 2 episodes of loss of consciousness associated with seizure-like activity. The telemetry strips during one of these episodes is shown in the exhibit. Which of the following is most likely to provoke a recurrent event in 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 the second day of hospitalization, he has 2 episodes of loss of consciousness associated with seizure-like activity.  The telemetry strips during one of these episodes is shown in the exhibit.  Which of the following is most likely to provoke a recurrent event in this patient?

Quizplus · Accepted Answer

Explanation: 11ec2b69_be33_8292_8f63_5d64681b7374_MD0005_00 This patient has developed acquired long QT syndrome (LQTS) as a result of interactions between medications (sotalol and azithromycin). The telemetry strips show 3 sinus beats with a prolonged QT interval, followed by a rapid ventricular rhythm consistent with polymorphic ventricular tachycardia (VT). Torsades de pointes (TdP) refers to the form of polymorphic VT that occurs in the setting of acquired or congenital QT prolongation and is characterized by cyclic alteration of QRS axis and/or morphology. TdP in patients with acquired LQTS is most commonly precipitated by premature ventricular beats followed by a compensatory pause (short-long RR intervals) that initiates the cycle of VT. It can also be provoked in patients with bradyarrhythmias (sinus bradycardia or frequent pauses), referred to as "pause-dependent" LQTS. Other causes of acquired LQTS are electrolyte imbalances (eg, hypomagnesemia, hypokalemia), selective serotonin reuptake inhibitors, hypothermia, and HIV infection. (Choice A) TdP can be triggered by an adrenergic surge (exercise or sudden arousal) in some patients with certain congenital forms of LQTS. However, there is no association with fever. (Choice B) Hyperglycemia (or hypoglycemia) is not a risk factor or trigger for drug-induced TdP. (Choice C) Hypokalemia, hypomagnesemia, and hypocalcemia (less common) increase the risk of developing recurrent episodes of TdP. No association is seen with hypernatremia. (Choice D) Structural heart disease, heart failure, and left ventricular hypertrophy are associated with an increased risk of developing drug-induced TdP. Hypertension alone is not associated with an increased risk of provoking TdP. Educational objective: The presence of bradyarrhythmias (sinus bradycardia or pauses) is associated with an increased risk of developing torsades de pointes in patients with drug-induced acquired long QT syndrome (LQTS). Common medications implicated in LQTS include antipsychotics, antidepressants, macrolides, fluoroquinolones, and antifungals. References: Polymorphic ventricular tachycardia, long QT syndrome, and torsades de pointes. (http://www.ncbi.nlm.nih.gov/pubmed/11233951)

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