Electrophysiology Studies (EPS) is a laboratory test that examines the electrical activity of the heart to find out where in the heart the cause of the arrhythmia is coming from. From the results, the doctor will prescribe whether to use antiarrhythmic drugs, a pacemaker, implantable cardioverter-defibrillator (ICD: Implantable Cardioverter Defibrillator), electrophysiological ablation or surgery. Cardiac electrophysiology testing will take place in a special room called the EPS room, or interventional cardiology room.