A 17-year-old girl is brought to the emergency department after an episode of syncope. The patient was eating her breakfast when she suddenly passed out. She regained consciousness spontaneously after approximately 2 minutes. The patient was diagnosed with an microbial infection for which an antimicrobial agent is prescriped. Her uncle died suddenly 2 years ago. A detailed evaluation reveals a decrease-in-function mutation in the KCNH2 gene, which codes for a voltage-gated potassium channel that is active during the repolarization phase of cardiomyocyte action potential. The patient's medication was causing further impairment of the ion channel function, leading to the incident of syncope. This patient was most likely taking which of the following medications?

Question

A 17-year-old girl is brought to the emergency department after an episode of syncope.  The patient was eating her breakfast when she suddenly passed out.  She regained consciousness spontaneously after approximately 2 minutes.  The patient was diagnosed with an microbial infection for which an antimicrobial agent is prescriped. Her uncle died suddenly 2 years ago.  A detailed evaluation reveals a decrease-in-function mutation in the KCNH2 gene, which codes for a voltage-gated potassium channel that is active during the repolarization phase of cardiomyocyte action potential.  The patient's medication was causing further impairment of the ion channel function, leading to the incident of syncope.  This patient was most likely taking which of the following medications?

Quizplus · Accepted Answer

Eductional Objective: Congenital long QT syndrome is commonly caused by a mutation that slows the delayed rectifier potassium current that repolarizes the cardiomyocyte action potential.  Certain medications (eg, macrolide antibiotics, antipsychotics, antiemetics) also slow the potassium repolarization current and prolong the QT interval.  Excessive QT prolongation can trigger serious cardiac arrhythmia (ie, torsades de pointes), resulting in syncope or sudden cardiac death.

A 17-Year-Old Girl Is Brought to the Emergency Department After