Proarrhythmia

Proarrhythmia
Like all antiarrhythmic agents, amiodarone may cause a worsening of existing arrhythmias or precipitate a new arrhythmia.

The most worrisome adverse effect is proarrhythmia, a drug-related arrhythmia worse than the arrhythmia being treated.

The above drugs can cause "proarrhythmia" (an increase in heart rhythm problems), "but in patients without heart disease, this risk is extremely small."
If these drugs don't work, then dofetilide and amiodarone can be considered.

See also: Tachycardia, Symptom, Surgery, Ventricular tachycardia, Arrhythmia