For example, vandetanib can cause serious ventricular arrhythmia leading to sudden death.

FORBES: Is the FDA Approving Drugs Too Quickly?

The electrical activity fails to die away properly, and moves around the muscle in a turbulent pattern causing an arrhythmia known as ventricular fibrillation.

BBC: Virtual heart

Ventricular fibrillation (VF) is one type of arrhythmia that is deadly.

CNN: Heart arrhythmias