This figure illustrates the time course of the medications that the patient took.{Monahan}  In relation to when the symptoms started, the most recently prescribed drug was ketoconazole.  Ketoconazole has not been associated with development of torsades de pointes when used by itself.

How did  ketoconazole interact with terfenadine to cause QT prolongation and torsades de pointes in this patient?  That question will be answered during the course of this module.

Monahan BP, Ferguson CL, Cleave ES, Lloyd BK, Troy J, Cantilena LR. Torsade de pointes occurring in association with terfenadine use. JAMA 1990; 264:2788-2790.