A 54-year-old man's paroxysmal atrial fibrillation is being assessed. The patient feels palpitations, pressure in the chest, dizziness, and shortness of breath during the episodes. For diabetes mellitus under diet management and hypertension, medical history is important. Prior tests revealed no valvular disease, no obstructive coronary artery disease, and a normal left ventricular ejection fraction. The decision is made to continue dofetilide medication. Initiation of this therapy increases this patient's risk for which of the following?

Question

Quizplus · Accepted Answer

Eductional Objective: In order to reduce repolarization and lengthen the effective refractory period, class III antiarrhythmics dofetilide and ibutilide block the fast component of the delayed-rectifier potassium current. The QT interval lengthens as a result, increasing the risk of polymorphic ventricular tachycardia (torsade de pointes).

A 54-Year-Old Man's Paroxysmal Atrial Fibrillation Is Being Assessed