Revised SPCs: Keppra (levetiracetam) products
Rare cases of ECG QT interval prolongation have been observed, so it should be used with caution in those: 1) with QTc-interval prolongation, 2) concomitantly treated with drugs affecting QTc-interval, or 3) with relevant pre-existing cardiac disease or electrolyte disturbances.
Source:
electronic Medicines compendium