Iohexol contrast medium induces QT prolongation in amiodarone patients

Amiodarone is widely used in ventricular tachyarrhythmias and atrial fibrillation, known to prolong QT-intervals. Concurrent administration of drugs prolonging QT- time can induce life-threatening ventricular tachyarrhythmia.QT-interval changes following use of Iohexol contrast-medium for coronarangiography were observed comparing 21 patients taking long-term amiodarone therapy with 21 controls not taking amiodarone or QT-prolonging drugs retrospectively.Concurrent use of Iohexol and amiodarone was associated with significant prolongation of QTc-interval (433, 95%CI: 419-448 ms vs. 480, 95%CI: 422-483 ms, P0.001) the day after coronarangiograpgy. 6/21 patients showed severe prolonged QTc-interval of500 ms.Caution is advised until more is known about pro-arrhythmic effects of Iohexol.