Helixtalk - Rosalind Franklin University's College Of Pharmacy Podcast

In this episode, we discuss the concerns of QTc prolongation, which can cause a fatal arrhythmia called torsades de pointes (TdP). We cover the difference between QT and QTc, how to interpret a QTc (and when it is inaccurate), common medications that prolong QTc, and how pharmacists can evaluate the risk of QTc/TdP in patients who are receiving QTc-prolonging therapies. Key Concepts The QTc interval is the QT interval that has been “corrected” for heart rate. In nearly all cases, when describing a QT interval, it should be expressed as the QTc. Although a prolonged QTc is usually defined as a QTc exceeding 450-480 msec, the risk of torsades de pointes (TdP) begins to become concerning when the QTc is more than 500 msec, 15-20% longer than baseline, or if the QTc has increased by more than 60 msec. Vaughan-Williams Class III antiarrhythmics are most implicated in QTc prolongation and TdP risk. These therapies include sotalol, dofetilide, and dronedarone. Although amiodarone is a class III antiarrhythmic, its