- Conditions and concomitant medication which may prolong the QTc interval, e.g. long-QT syndrome, patients with hypokalemia, receiving Class I1 (e.g. quinidine, procainamide) or class III (amiodarone, sotalol) known antiarrhythmogenic drugs, or other medication that are known to prolong QT interval (such as cisapride, erythromycin, antipsychotic and antidepressants) - since there is a lack of clinical experience and potential risks with the concomitant use of these medication with the MRI contrast